taxonID	type	description	language	source
0399C326FFADFFC453BB04CFFBFBFB2F.taxon	type_taxon	Type species. Atopobathynella valdiviana (Noodt, 1965) Parabathynella valdiviana Noodt, 1965 Other species: see Table 7	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFADFFC453BB04CFFBFBFB2F.taxon	diagnosis	Amended diagnosis (after Perina et al. 2023 b). Antennula 6 - segmented often showing sexual dimorphism on the inner margin of the second article, with female bearing one simple seta, and male an antennal organ with one or two setae that can be modified. Antenna one-segmented, with three smooth setae (one inner proximal and two apical) and an apical seta. Labrum heterodont with numerous teeth. Mandible with pars incisiva with three teeth (in one case four); lobe with row of five claws (Borstenlobus). Distal endite of maxillula with five or six claws. Maxilla four-segmented (in two cases three-segmented) with setal formula: 2 - 2 / 4 - n- 1 / 7 (the third article can have a variable number “ n ” of setae, while the fourth article can have up to 7 setae). Six or seven pairs of thoracopods. Epipod present or absent in thoracopod I, always present in thoracopods II to VII. Exopod of thoracopods I to VII one-segmented. Exopod of thoracopods II to VII usually with two terminal setae and one ventral subterminal one (one species has two ventral setae, one species has none); endopod of thoracopods I to VII four-segmented, fourth article tiny, thoracopods II to VII with one or two very long claws on the fourth article; setal formula of endopod II to VII articles 1 to 3: 0 + 0 / 0 + 1 / 0 + 1. Male thoracopod VIII small, semicircular in lateral view; protopod massive, anteriorly with dentate lobe, and often with a small protrusion; outer lobe drawn out into a conical projection directed anteriorly; basipod triangular or round / paddle-like, as large as outer lobe, with one or two setae of uncertain interpretation that could represent endopod and / or exopod. Pleopod I consisting of one seta. Sympod of the uropod with homonomous or inhomonomous row of several spines; endopod with dagger-like extension and two or three setae at its base (only one seta in one species); exopod of uropod often with ventromedial seta and 2 to 4 terminal / subterminal setae.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA2FFCF53BB002CFCE5FC81.taxon	description	(Figs. 6 – 7)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA2FFCF53BB002CFCE5FC81.taxon	materials_examined	Material examined. Holotype male. AUSTRALIA: Western Australia: Brockman Pilbara, karaman BS 1 _ Kara 02, 22 ° 34 ' 29.6998 " S, 117 ° 11 ' 23.8466 " E, 20 February 2021, P. Runham, S. Floeckner (WAMC 78930 — BES 10765 e — BMR 02603, permanent slide). Paratypes AUSTRALIA: Western Australia: 1 female, Brockman, Pilbara, Boolgeeda Creek, karaman BS 4 - KC 01, 22 ° 34 ' 32.1312 " S, 117 ° 11 ' 23.7006 " E, 17 April 2019, S. Callan, M. Lythe (WAM C 78920 — BES 6041 permanent slide); 1 female, 1 male (WAM C 78921 — BES 6041 permanent slide), same details as above; 1 female (WAM C 78923 — BES 6814 — BMR 00622, permanent slide), same details as above; 1 female (WAM C 78924, BES 5905, permanent slide) same details as above; 1 male (WAM C 78925 — BES 5905, permanent slide) same details as above; 1 female (WAM C 78926 — BES 5905, permanent slide) same details as above; 1 female (WAM C 78924 — BES 5905, permanent slide) same details as above; 1 male (WAM C 78928 v — BES 10765 c — BMR 02601 permanent slide) same details as holotype; 1 male (WAM C 78929 — BES 10765 d — BMR 02602 permanent slide) same details as holotype. Additional material AUSTRALIA: Western Australia: 1 male, Brockman, Pilbara, karaman BS 1 - KC 02, 22 ° 34 ' 29.6998 " S, 117 ° 11 ' 23.8466 " E, 20 February 2021, P. Runham, S. Floeckner (WAMC 78931 — BES 10765 f, in alcohol); 1 specimen (sex not available), Brockman, Pilbara, Boolgeeda Creek, karaman BS 4 - KC 01, 22 ° 34 ' 32.1312 " S, 117 ° 11 ' 23.7006 " E, 17 April 2019, S. Callan, M. Lythe (WAM C 82065 — BES 5503 — BMR 00673, in alcohol); 1 male (WAM C 78922 — BES 6041, in alcohol), same details above; 1 female, 1 male, 1 juvenile (WAM C 78927 — BES 5905, in alcohol), same details as above.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA2FFCF53BB002CFCE5FC81.taxon	diagnosis	Diagnosis. Atopobathynella abelloana sp. nov. belongs to a group of Atopobathynella species that have antennal organ (AO) without protuberance and with two similar special setae; distal endite of maxillula with six claws; three setae on the exopod of all thoracopods (except thoracopod I); sympod of the uropod with inhomonomous spines; exopod of the uropod with two distal setae and furcal rami with few spines. It differs from all other Atopobathynella species by the highest number of setae on the third article of MxII, (16), outer lobe of male ThVIII “ finger-shaped ”, basipod with a crest and without visible setae. The sequenced specimens differ from all the other Atopobathynella species sequenced by COI = 12.2 – 22.3 % and 12 S = 11.6 – 33.6 % (Appendices 3, 4).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA2FFCF53BB002CFCE5FC81.taxon	description	Description male holotype (WAM C 78930). Body length of 0.91 mm. Body almost eight times as long as maximum width, elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of body. Antennula (Fig. 6 A): six-segmented. Articles narrowing from the first to the last one, the second article is the longest, slightly longer than the first, which is longer than the third, the fourth and fifth are equal in length and shorter than the third, and the last article is the shortest. Antennal organ not protruded, represented by two similar strong ventral setae that reach half of the length of the fourth article. Inner flagellum small and almost square. Article five and six with three terminal aesthetascs respectively. Antennular setation as in Fig. 6 A. Antenna (Fig. 6 C): one-segmented; very short and rectangular with three smooth setae, two terminal and one subterminal. Labrum (Fig. 6 D): slightly convex, free edge with 18 teeth, eight on each side and two centrals with distal end denticulated. Paragnaths (Fig. 6 H): rudimental structure that could represent paragnaths. Mandible (Fig. 6 E): pars incisiva with three teeth; pars molaris with five strong claws, the most distal modified and denticulated, thicker and almost perpendicular to the rest, the two most proximal ones joined together; tooth of ventral edge small and triangular. Mandibular palp with one long distal seta reaching beyond the pars incisiva. Maxillula (Fig. 6 F): proximal endite with four unequal claws; distal endite with six claws: two apical smooth and four denticulate; three smooth subterminal setae on the outer distal margin. Maxilla (Fig. 6 G): four-segmented, setal formula 2, 3, 16, 1. Thoracopods I to VII (Figs. 7 A – G): length slightly increasing from thoracopod one to three, last four similar in size. Small epipod present in thoracopod II to VII, about half (or slightly over) the length of the corresponding basipod. All basipods with one distolateral seta as long as the first article of the endopod (except in ThI, which is slightly shorter). Exopod one-segmented in all thoracopods; exopod of ThI shorter than corresponding two first articles of the endopod, exopod of ThII to VII similar in length to the first two articles of the endopod. Exopod of ThI with two distal setae, the outer one short. Exopod of Ths II to VII bearing three barbed setae, two terminal (with the inner one very long) and one subterminal slightly longer than the outer terminal seta. Endopod four-segmented, first article short with one inner seta on ThI, and no seta on the rest of thoracopods; second and third articles long and similar in length; second article with one outer plumose seta in all thoracopods and one smooth inner seta only on ThI; third article with one inner seta on ThI, and one small distal outer seta on the rest of thoracopods; fourth article very reduced with two strong claws of different length on thoracopod I, and only one long strong claw on ThII to VII. Setal formula of endopods as follows: ThI 1 + 0 / 1 + 1 / 1 + 0 / 2 ThII to VII 0 + 0 / 0 + 1 / 0 + 1 / 1 Thoracopod VIII (Fig. 6 J): compact, like a balloon. Penial region with massive protopod with frontal protrusion. Outer lobe elongated, like a finger, reaching the distal end of basipod and not defined at base in latero-external view. Dentate lobe with four distal teeth. Inner lobe shorter than outer lobe. Basipod with one small frontal crest over-reaching the penile projection and no visible seta. Pleopod I (Figs. 7 H): long plumose seta on each side, located on the anterior third of the first segment of the pleon. Uropod (Fig. 7 I): sympod about four times the length of the endopod and five times as long as wide, with eight spines, the distal longest, occupying two thirds of its length. Endopod as long as exopod, distally drawn out into a dagger-shaped structure bearing a row of setules, distolateral angle bearing two similar plumose setae that exceed the tip of the dagger-shaped structure. Exopod with two terminal barbed setae, and one basal plumose seta. Pleotelson (Fig. 7 J): with one small lateral plumose seta on each side; anal operculum not protruded. Furca (Fig. 7 J): rami robust and rectangular, with four thick and short barbed spines; the three distal spines similar in size, the basal one is the thinnest. Two dorsal plumose setae, the inner one very short and the outer one about twice as long as the spines. Female paratypes differ from male in the second antennular segment (Fig. 6 B) that bears no antennal organ, and in the small pointed thoracopod VIII (Fig. 6 I). Variability: variability was observed in body size (males 0.87 – 1.06 mm and females 0.80 – 0.82 mm), number of teeth on labrum (18 – 20) and number of spines on sympod of uropod (7 – 8).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA2FFCF53BB002CFCE5FC81.taxon	distribution	Distribution and remarks. Atopobathynella abelloana sp. nov. has been collected in the hyporheic environment at Boolegeeda creek (Ashburton River) in three geographically close locations (Fig. 1). The species was previously known by Biologic Environmental Surveys as Atopobathynella sp. “ Biologic-PBAT 013 ”. Despite being collected geographically close to A. rudini (less than 0.5 km), they are genetically distant, and A. abelloana, appears to be more closely related to putative species A. sp. PBAT 032, A. sp. 20 (EM 2019) and A. sp. H SPA 050 occurring in the Onslow River Catchment (Figs. 1, 5 clade 7).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA2FFCF53BB002CFCE5FC81.taxon	etymology	Etymology. The name of the species is dedicated to, Jenny Abello, a colleague who has extensively worked on the hydrogeology of the area where the species was collected.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA6FFF253BB06F2FEADF891.taxon	description	(Figs. 8 – 9)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA6FFF253BB06F2FEADF891.taxon	materials_examined	Material examined. Holotype male. AUSTRALIA: Western Australia: Brockman, Pilbara, Karaman GBOT 2 KARA 08 MCDM, 22 ° 42 ' 59.1726 " S, 117 ° 19 ' 34.554 " E, 14 September 2022, M. Curran, D. Main (WAMC 78913 — BES 17988 — BMR 04610, permanent slide). Paratypes: AUSTRALIA: Western Australia: 1 female, WAM C 78911 — BES 17988 — BMR 04608, permanent slide, same details as holotype. 1 female, WAM C 78912 — BES 17988 — BMR 04609, permanent slide, same details as holotype. 1 male, WAM C 78914 — BES 17988 — BMR 04611, permanent slide, same details as holotype. 1 male, WAM C 78915 — BES 17988 — BMR 04612, permanent slide, same details as holotype. Additional material: 75 specimens in alcohol (WAM C 78939 — BES 17988), same details as holotype; 1 male (WAM C 78940 — BES 18677), same details as holotype.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA6FFF253BB06F2FEADF891.taxon	diagnosis	Diagnosis. Atopobathynella beasleyensis sp. nov. belongs to a group of Atopobathynella species that have antennal organ (AO) with protuberance and two setae of different length; distal endite of maxillula with five claws; only two setae in the exopod of all thoracopods; homonomous sympod of the uropod; exopod of the uropod with three distal setae and furca with more than five spines. It differs from all other species (except A. chelifera) by the presence of two setae on exopod of all thoracopods, and by a bilobed outer lobe of male ThVIII. The sequenced specimens differ from all the other Atopobathynella taxa sequenced by COI = 11.1 – 21.5 % and 12 S = 33.1 – 42.3 % (Appendices 3, 4).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA6FFF253BB06F2FEADF891.taxon	description	Description male holotype (WAMC 78913). Body length of 0.80 mm. Body almost eight times as long as maximum width, elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of body. Antennula (Fig. 8 A): six-segmented. Articles narrowing from the first to the last one, the second article is the longest, slightly longer than the first, which is longer than the third, the fifth and sixth are equal and shorter than the third, and the fourth is the shortest. Antennal organ represented by two strong, ventral setae of different length and arranged on two protuberances, the longest extends beyond the distal end of fourth article and is over three times longer than the other. Inner flagellum small and almost square with three setae. Articles five and six with three terminal aesthetascs each. Antennular setation as in Fig. 8 A. Antenna (Fig. 8 C): one-segmented with four smooth setae, three terminal and one subterminal. Labrum (Fig. 8 D): almost flat, free edge with 16 teeth, seven on each side and two central ones with the distal end denticulated. Paragnaths: absent. Mandible (Fig. 8 E): pars incisiva with three teeth; pars molaris with four strong claws, the most distal one thicker, denticulated, and almost perpendicular to the others, the two most proximal claws joined together; tooth on ventral edge absent. Mandibular palp with one seta not reaching beyond the pars incisiva. Maxillula (Fig. 8 G): proximal endite with four unequal claws; distal endite with five dentated claws; three smooth subterminal setae on the outer distal margin. Maxilla (Fig. 8 I): four-segmented, setal formula 2, 3, 11, 1. Thoracopods I to VII (Figs. 9 A – G): length slightly increasing from thoracopod one to three, last four similar in size. Small epipod present in ThII to VII, just over half the length of the corresponding basipod. All basipods with one distolateral seta about the length of the first article of the endopod. Exopod one-segmented in all thoracopods; exopod of ThI very short, slightly longer than the first article of the endopod, exopod of ThII to VII similar in length to the first two articles of the endopod. Exopod of ThI to VII bearing two terminal barbed setae, inner seta long, twice as long as outer one. Endopod four-segmented, first article short with one inner seta on ThI, and no seta on the rest of thoracopods; second and third articles long and similar in length; second article with one outer plumose seta in all thoracopods, and one inner smooth seta on thoracopod I only; third article with one inner seta on ThI, and one small outer distal seta on the rest of thoracopods; fourth article very reduced with two strong claws of different length on ThI, and only one long strong claw on ThII to VII. Setal formula of endopods as follows: ThI 1 + 0 / 1 + 1 / 1 + 0 / 2 ThII to VII 0 + 0 / 0 + 1 / 0 + 1 / 1 Thoracopod VIII (Figs. 8 J, K): compact, like a balloon slightly elongated. Penial region with massive protopod. Outer lobe rounded with frontal protrusion, shorter than the distal end of basipod, not defined at base in latero-external view and similar to the inner lobe. Dentate lobe with four teeth, two distal and two subdistal. Basipod with one very small frontal crest and two setae of uncertain origin (possibly exopod or endopod). Pleopod I (Figs. 9 H): long plumose seta located on the anterior third of the first segment of the pleon in each side. Uropod (Fig. 9 I): sympod almost seven and a half times the length of the endopod and almost five times as long as wide, with nine spines, the three distal ones slightly shorter than the six proximal, occupying the distal half of the sympod. Exopod one and a half longer than endopod, with three terminal barbed setae, and one basal seta. Endopod very short distally drawn out into a very long dagger-shaped structure, with setules, distolateral angle bearing two plumose setae, of different lengths (the inner one almost twice as long as outer one), that exceed the tip of the dagger-shaped structure. Pleotelson (Fig. 9 J): with one short lateral plumose seta on each side; anal operculum not protruded. Furca (Fig. 9 J): rami robust and rectangular, with six barbed spines; two distal spines longer than basal ones that are equal in length. Two dorsal plumose setae, inner seta short, outer seta three times longer than distal spines. Female paratype differs from male in the second antennular segment (Fig. 8 B) that bears no antennal organ, but a long smooth seta; five claws on pars molaris of the mandible; thoracopod VIII (Fig. 8 H) reduced to a small denticle-like appendage. Variability: variability was observed in body size (males 0.67 – 0.86 mm and females 0.94 – 1.14 mm), and number of spines on sympod of uropod (8 – 11) and furca (5 – 7).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA6FFF253BB06F2FEADF891.taxon	distribution	Distribution and remarks. Atopobathynella beasleyensis sp. nov. has been collected at only one site in the hyporheic habitat of the Beasley Creek, a tributary of the Ashburton River. This species was previously known by Biologic Environmental Surveys as Atopobathynella sp. “ Biologic-PBAT 050 ”. Despite being geographically close to A. abelloana sp. nov. and A. rudini sp. nov. (less than 30 km), our results indicate it is sister species to A. sp. GrPar, occurring about 60 km southeast (Figs. 1, 5).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFA6FFF253BB06F2FEADF891.taxon	etymology	Etymology. The name of the species derives from the Beasley Creek in the Pilbara, where this species was collected.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9AFFF653BB05CBFF59FD11.taxon	description	(Figs. 10 – 11)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9AFFF653BB05CBFF59FD11.taxon	materials_examined	Material examined. Holotype female. AUSTRALIA: Western Australia: Miralga Creek, Sulphur Spring, Pilbara, karaman SSK 0021, 21 ° 07 ' 23.0106 " S, 119 ° 12 ' 00.0655 " E, 15 September 2019, F. Rudin, P. Runham (WAMC 78880 — BES 7664 b, permanent slide). Male unknown. Additional material: AUSTRALIA: Western Australia: 1 juvenile, Miralga Creek, Sulphur Springs, Pilbara karaman SSK 002, 21 ° 07 ' 13.3339 " S, 119 ° 11 ' 54.2026 " E, 12 July 2019, P. Runham, D. Main (WAMC 78879 – BES 5980 a, in alcohol); 1 juvenile, Miralga Creek, Sulphur Springs, Pilbara karaman STXKARA 01, 21 ° 06 ' 37.7343 " S, 119 ° 11 ' 40.1582 " E, 17 May 2019, P. Runham, D. Main (WAMC 78883 — BES 8285, in alcohol); 3 juveniles in alcohol, karaman STXKARA 01, 17 May 2019, P. Runham, D. Main (WAMC 78937 — BES 7463).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9AFFF653BB05CBFF59FD11.taxon	diagnosis	Diagnosis. Atopobathynella runhami sp. nov. belongs to a group of Atopobathynella species that have distal endite of maxillula with five claws; homonomous sympod of the uropod; exopod of the uropod with two distal setae and furca with few spines. It differs from all other species of Atopobathynella by the female ThVIII “ tongue ” shaped. The sequenced specimens differ from all the other Atopobathynella species sequenced by COI = 16.1 – 21.4 % and 12 S = 28.7 – 42.3 % (Appendices 3, 4).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9AFFF653BB05CBFF59FD11.taxon	description	Description female holotype (WAMC 78880). Body length of 1.06 mm. Body about six and a half times as long as maximum width, elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of body. Antennula (Fig. 10 A): six-segmented. First two articles almost square, first three articles with similar length, third article longer than the last three ones, which are equal in length. Inner flagellum small and almost square, with three setae. Articles five and six with three terminal aesthetascs each. Antennular setation as in Fig. 10 A. Antenna (Fig. 10 B): one-segmented with three setae, two terminal and one subterminal. Labrum (Fig. 10 C): almost flat, free edge with 16 teeth, seven on each side, long, and two smaller centrals. Paragnaths: absent. Mandible (Fig. 10 D): pars incisiva with three teeth; pars molaris with five claws, the most distal one thicker, denticulated, and almost perpendicular to the others, the two most proximal ones joined together; tooth on ventral edge absent. Mandibular palp with one long distal seta reaching beyond the pars incisiva. Maxillula (Fig. 10 E): proximal endite with four unequal claws; distal endite with five claws, two distal ones smooth, and the other three denticulated, with the basal claw thinner than the others; three smooth subterminal setae on the outer distal margin. Maxilla (Fig. 10 F): four-segmented, setal formula 2, 3, 10, 1. Thoracopods I to VII (Figs. 11 A – G): length slightly increasing from ThI to III, last four similar in size. Epipod present in ThII to VII, about half of the length of the corresponding basipod (Fig. 11 A). All basipods with one distolateral seta as long as the first article of the endopod of ThI, and much longer than the first article in other Ths. Exopod one-segmented in all thoracopods; exopod of ThI reaching the middle of the second article of the endopod; exopod of ThII to VII similar in length to the first two articles of the endopod. Exopod of ThI to VII bearing three barbed setae, two terminals, with the outer one very small in ThI, and the inner one long, about five times as long as the outer one in all Ths, one subterminal seta 1.5 times longer than the outer distal one. Endopod four-segmented, first article short with one seta on ThI, and no seta on the rest of thoracopods; second and third articles long and similar in length; second article with one outer plumose seta in all thoracopods and one inner smooth setae only on ThI; third article with one inner seta on ThI and one small outer seta on the rest of thoracopods; fourth article very reduced with two strong claws of different length and one seta on ThI and only one long strong claw on ThII to VII. Setal formula of endopods as follows: ThI 1 + 0 / 1 + 1 / 1 + 0 / 3 (1) ThII to VII 0 + 0 / 0 + 1 / 0 + 1 / 1 Thoracopod VIII (Figs. 10 G): very small, “ tongue ” shaped. Pleopod not seen. Uropod (Fig. 11 H): sympod about four times as long as wide, two and half times the length of the exopod and about three times the length of the endopod, with seven and five subequal spines, occupying less than the distal half of the sympod. Exopod one third longer than the endopod, with two similar terminal barbed setae, and one basal plumose seta. Endopod distally drawn out into a long dagger-shaped structure, distolateral angle bearing two plumose setae of different lengths, the inner one 1 / 3 longer than the outer one, and both exceed the tip of the dagger-shaped structure. Pleotelson (Fig. 11 I): with one small lateral plumose seta on each side; anal operculum not protruded. Furca (Fig. 11 I): rami robust and almost square, with four barbed spines; whose lengths slightly increase from the basal one, which is the shortest, and half of the size of the distal one. Two dorsal plumose setae, the inner one very short and the outer one about two times longer than the distal spines.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9AFFF653BB05CBFF59FD11.taxon	distribution	Distribution and remarks. Atopobathynella runhami sp. nov. has been collected in the hyporheic habitat at three geographically close sites near Miralga creek, a tributary of the de Grey River Catchment (Fig 1). It was collected in one of the karaman samples with A. jessicae, but our results indicate that A. runhami is genetically distant to A. jessicae and all other Atopobathynella sequenced (Fig. 5).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9AFFF653BB05CBFF59FD11.taxon	etymology	Etymology. The name of the species is dedicated to Phil Runham, a colleague and one of the collectors of the species.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9FFFF553BB0642FD78F9D5.taxon	description	(Figs. 12 – 13)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9FFFF553BB0642FD78F9D5.taxon	materials_examined	Material examined. Holotype male. AUSTRALIA: Western Australia: Miralga Creek, Pilbara, karaman STXKARA 01, 21 ° 06 ' 37.7343 " S, 119 ° 11 ' 40.1582 " E, 17 May 2019, D. Main, P. Runham (WAMC 78881 — BES 8283, permanent slide). Paratype: 1 female, same detail as holotype (WAM C 78882 — BES 8284, permanent slide).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9FFFF553BB0642FD78F9D5.taxon	diagnosis	Diagnosis. Atopobathynella jessicae sp. nov. belongs to a group of Atopobathynella species that have antennal organ (AO) without protuberance and formed by two setae of different length; distal endite of maxillula with five claws; inhomonomous spines on sympod of the uropod; exopod of the uropod with two distal setae. It differs from all other species in the male ThVIII, which has dentate lobe like a four-fingered glove, outer lobe vase-shaped (tall cap that tapers upwards), and basipod with three lobes, one of these with distal spicules. The sequenced specimens differ from all the other Atopobathynella species sequenced by COI = 13.6 – 21.0 % and 12 S = 26 – 37 % (Appendices 3, 4).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9FFFF553BB0642FD78F9D5.taxon	description	Description male holotype (WAMC 78881). Body length of 0.93 mm. Body eight times as long as maximum width, elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of body. Antennula (Fig. 12 A): six-segmented. All articles wide, of similar width and rectangular. The first is the longest, the second and third are similar and longer than the fourth and fifth, which are equal in length, and the last article is the shortest. Antennal organ represented by two ventral setae of different length, thicker at base, with the longest two times the length of the other one and extending beyond the distal end of the third article. Inner flagellum very small, almost square, with three setae. Small plumose setae present on the inner angle of the distal end of the fourth segment, in addition to the two typical plumose setae (in this case short) located on a small protuberance. Articles five and six with three terminal aesthetascs each. Antennular setation as in Fig. 12 A. Antenna (Fig. 12 C): one-segmented with three smooth setae, two terminal and one subterminal. Labrum (Fig. 12 D): almost flat, free edge with 16 teeth, seven long teeth on each side and two centrals smaller. Paragnaths: absent. Mandible (Fig. 12 E): pars incisiva with three teeth; pars molaris with five claws, the most distal one thicker, denticulated, and almost perpendicular to the others, the two most proximal ones joined together; tooth on ventral edge present. Mandibular palp with one long distal seta reaching beyond the pars incisiva. Maxillula (Fig. 12 F): proximal endite with four unequal claws; distal endite with five claws, with the two distal ones smooth and the other three denticulated; three smooth subterminal setae on the outer distal margin. Maxilla (Fig. 12 G): four-segmented, setal formula 2, 3, 11, 1. Thoracopods I to VII (Figs. 13 A – G): length slightly increasing from thoracopod one to four, last three similar in size. Epipod present in all thoracopods, about half the length of the corresponding basipod. All basipods with one distolateral seta shorter than the first article of the endopod on ThI to III and exceeds the distal end of the first article in the other Ths. Exopod one-segmented in all thoracopods; exopod of ThI (Fig. 13 A) reaching the distal end of the second article of the endopod; exopod of ThII similar in length to the first two articles of the endopod and slightly longer than the first two articles of the endopod in ThIII to VII. Exopod of ThI bearing two barbed terminal setae, the outer very small, the inner one long, reaching the distal end of the longest claw of article four of the endopod; exopod of ThII to VII bearing two barbed terminal setae (the outer one very small, the inner one long, reaching the distal end of the claw of article four of the endopod on ThII and much longer in the rest of thoracopods) and one subterminal barbed seta half of the length of the long distal seta in ThIV and V, and about three times shorter in ThVI – VII. Endopod four-segmented, first article short with one seta on Th I, and no seta on the rest of thoracopods; second and third articles long and similar in length; second article with one outer plumose seta in all thoracopods, and one inner smooth seta on Th I only; third article with one inner and one very short outer seta on ThI, and one small outer seta on the rest of thoracopods; fourth article very reduced with two strong claws of different length on thoracopod I, and one long strong claw on thoracopod II to VII. Setal formula of endopods as follows: ThI 1 + 0 / 1 + 1 / 1 + 1 / 2 ThII to VII 0 + 0 / 0 + 1 / 0 + 1 / 1 Thoracopod VIII (Figs. 12 H – I): compact, like a balloon. Penial region with massive protopod. Outer lobe vase-shaped (tall cap that tapers upwards), which reaches the distal end of basipod, well defined at base in latero-external view. Short inner lobe. Dentate lobe like as four-fingered glove. Basipod without delimited base, with three lobes, one with distal spicules and the other two oval shaped. Basipod with seta of uncertain origin. Pleopod not seen. Uropod (Fig. 13 H): sympod about four times as long as wide, about five times the length of the exopod and endopod, which are similar in length, sympod with six inhomonomous spines (the most distal one bigger) occupying the distal half of the sympod. Exopod with two terminal barbed setae, and one basal long plumose seta. Endopod distally drawn out into a long dagger-shaped structure, distolateral angle bearing two plumose setae, one reaching the end of the endopod, while the other one extends beyond. Pleotelson (Fig. 13 I): with one lateral plumose seta on each side; anal operculum not protruded. Furca (Fig. 13 I): rami robust and conical, with five barbed spines; the three basal ones smaller, just over half of the size of the distal spine. Two dorsal plumose setae, the inner one very short and the outer one as long as the distal spines. Female paratype differs from male in the second antennular segment (Fig. 12 B) that bears no antennal organ, but a small seta, and in the reduced stalk / tongue-like thoracopod VIII (Fig. 12 J). Variability: was observed in body size: male 0.93 mm, female 0.82 mm.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9FFFF553BB0642FD78F9D5.taxon	distribution	Distribution and remarks. Atopobathynella jessicae sp. nov. has been collected in one Karaman sample near the Miralga creek, a tributary of the De Grey River Catchment (Fig 1). It appears distantly related to all other Atopobathynella taxa (Fig. 5).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9FFFF553BB0642FD78F9D5.taxon	etymology	Etymology. The name of the species is dedicated to a colleague, Jessica Delaney, who has extensively sampled the Pilbara region for aquatic and hyporheic fauna.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9CFFF953BB0306FD71FC79.taxon	description	(Figs. 14 – 15)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9CFFF953BB0306FD71FC79.taxon	materials_examined	Material examined. Holotype male. AUSTRALIA: Western Australia: Miralga Creek, Shaw River, Pilbara, karaman MCK 004, 20 ° 41 ' 43.5454 " S, 119 ° 19 ' 50.4250 " E, 10 July 2019, D. Main, P. Runham (WAMC 78888 — BES 8290 permanent slide). Paratypes: 1 female (WAM C 78887 — BES 8289), permanent slide, same details as holotype; 1 male (WAMC 82096 — BES 7211) permanent slide, same details as holotype; 1 female (WAMC 82097 — BES 7211) permanent slide, same details as holotype. Additional material: 4 males, 4 females, 5 juveniles in ethanol (WAMC 78938 — BES 7211), same details as holotype.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9CFFF953BB0306FD71FC79.taxon	diagnosis	Diagnosis. Atopobathynella shawensis sp. nov. belongs to a group of Atopobathynella species that have antennal organ (AO) without protuberance and with two strong setae, which reaches beyond half the length of article three; distal endite of maxillula with five claws; sympod of the uropod with inhomonomous spines; exopod of the uropod with two distal setae. It differs from all other species by the presence of a trapezoidal outer lobe, bilobed basipod on male ThVIII, and anal operculum slightly protruded. The sequenced specimens differ from all the other Atopobathynella species sequenced by COI = 11.2 – 20.5.0 % (Appendix 2; 12 S sequences not obtained).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9CFFF953BB0306FD71FC79.taxon	description	Description male holotype (WAMC 78888). Body length of 0.83 mm. Body about seven and a half times as long as maximum width, elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of body. Antennula (Fig. 14 A): six-segmented. AO represented by two thick setae with no protuberance. Articles one to five thick, rectangular, sixth article half the thickness of the others. First two articles similar in length and longest, third and sixth articles similar in length and slightly shorted than first two, fourth and fifth articles similar in length and slightly shorter than others. Antennal organ represented by one ventral seta which reaches half the length of article three. Inner flagellum small and square with three setae. Plumose setae absent on the internal angle of the distal end of the fourth segment, two typical outer plumose setae present, one short and one long extending beyond the distal end of fifth article, both on the typical protuberance. Articles five and six with three terminal aesthetascs each. Antennular setation as in Fig. 14 A. Antenna (Fig. 14 C): one-segmented with three smooth setae, two terminal and one subterminal. Labrum (Fig. 14 D): flat, free edge with 12 main teeth. Paragnaths: absent. Mandible (Fig. 14 E): pars incisiva with three teeth; pars molaris with five claws, the most distal denticulated, thicker and on about a 45 ˚ angle from the others, the two most proximal claws joined together; tooth on ventral edge absent. Mandibular palp with one distal seta that does not reach the distal end of the pars molaris. Maxillula (Fig. 14 F): proximal endite with four unequal claws; distal endite with five claws, two distal ones smooth and other three ones denticulated, the most basal claw thinner than others; three smooth subterminal setae on the outer distal margin. Maxilla (Fig. 14 G): four-segmented, setal formula 2, 4, 10, 1. Thoracopods I to VII (Figs. 15 A – G): length slightly increasing from ThI to IV, ThV is the longest, ThVI and VII shorter than ThV. Epipod present in all thoracopods, about half of the length of the corresponding basipod, except in ThVII, which is one third the length of the basipod. All basipods with one distolateral seta similar in length or slightly longer than the first article of the endopod. Exopod one-segmented in all thoracopods; exopod of ThI (Fig. 10 A) reaching the distal end of the second article of the endopod and bearing two terminal barbed setae; exopod of ThII to VII longer than the first two articles of the endopod and bearing three barbed setae, two terminal ones of different length, with the outer one shorter than the inner one, subterminal seta slightly longer than outer seta on all thoracopods; internal distal seta of exopod reaching the distal end of the longest claw of the endopod article four in ThII, slightly shorter in ThI, and extending beyond in the rest of thoracopods. Endopod four-segmented, first article short, about half the length of the second and third article, with one inner seta on ThI, and no seta on other thoracopods; second and third articles long and similar in length in all thoracopods; second article with one outer plumose seta in all thoracopods and one inner smooth seta on ThI only; third article with one inner seta on ThI and one small outer seta on the rest of thoracopods; fourth article very reduced with two strong claws of different length and one seta on ThI, and one long strong claw on thoracopod II to VII. Setal formula of endopods as follows: ThI 1 + 0 / 1 + 1 / 1 + 0 / 3 (1) ThII to VII 0 + 0 / 0 + 1 / 0 + 1 / 1 Thoracopod VIII (Figs. 14 H – I): compact, like a balloon. Penial region with massive protopod. Trapezoidal outer lobe, not reaching the distal end of basipod, well defined at base in latero-external view. Inner and dentate lobe similar to outer lobe in size and shape. Dentate lobe with two teeth like small spines. Basipod without delimited base, with two blunt lobes, with basipodial seta. One seta on basipod of uncertain origin. Pleopod I (Figs. 15 H): one long plumose seta located on the anterior third of the first segment of the pleon in both sides. Uropod (Fig. 15 I): sympod almost four times as long as wide, about three times the length of the exopod and almost four times the length of endopod, with seven inhomonomous spines occupying the distal half of the sympod, with distal spine bigger. Exopod with two terminal barbed setae of different length, and one short basal plumose seta. Endopod distally drawn out into a very long dagger-shaped structure longer than the exopod, distolateral angle bearing two plumose setae, the outer one a third longer than the inner one and almost twice the length of the dagger-shaped structure. Pleotelson (Fig. 15 J): with one plumose lateral seta one each side; anal operculum slightly protruded. Furca (Fig. 15 J): rami robust and trapezoidal, with six barbed spines; three basal ones smaller, just over half the length of the distal spines, two distal spines longest. Two plumose dorsal setae, inner seta very short and outer seta about twice the length of distal spines. Female paratype differs from male in the second antennular segment (Fig. 14 B) that bears no antennal organ, but one smooth seta, and in the small denticle-like thoracopod VIII (Fig. 14 J). Variability: was observed in body length (males: 0.83 – 094 mm, females 1.19 – 1.31), number of spines on sympod (five to seven), and number of spines on furca (six – seven).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9CFFF953BB0306FD71FC79.taxon	distribution	Distribution and remarks. Atopobathynella shawensis sp. nov. has been collected from one site in hyporheic habitat near the Shaw River (a tributary of the De Grey River Catchment, Fig. 1). Atopobathynella shawensis sp. nov. has the outer seta on uropodal exopod longer than the inner one, as in the three Indian species A. indica, A. nellorensis and A. inopinata (Bandari et al., 2017), and this is the character initially described as a defining character for the genus Kimberleybathynella. It forms a monophyletic clade with A. yarriensis and A. sp. PBAT 031 (Fig. 5), collected in a perched aquifer at Yarrie Ridge and in the hyporheic environment at the McPhee Creek respectively, both in the De Grey Catchment (Fig. 1).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF9CFFF953BB0306FD71FC79.taxon	etymology	Etymology. The name of the species derives from the Shaw River in the Pilbara (a tributary of the De Grey River Catchment) where this species was collected.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF90FFFC53BB06AAFAE0F9A9.taxon	description	(Figs. 16 – 17)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF90FFFC53BB06AAFAE0F9A9.taxon	materials_examined	Material examined. Holotype female. AUSTRALIA: Western Australia: Brockman, Boolgeeda Creek, Pilbara, Karaman BS 4 - KC 08 22 ° 34 ' 29.2764 " S, 117 ° 11 ' 10.1645 " E, 21 August 2019, F. Rudin, P. Runham (WAMC 78933 — BES 6368, permanent slide); 1 juvenile (WAMC 78932 — BES 7410 — BMR 00527) in alcohol. Male unknown.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF90FFFC53BB06AAFAE0F9A9.taxon	diagnosis	Diagnosis. Atopobathynella rudini sp. nov. belongs to a group of Atopobathynella species that have distal endite of maxillula with five claws; sympod of the uropod with inhomonomous spines; exopod of the uropod similar in length to endopod, with two distal setae; anal operculum protruded. The sequenced specimens differ from all the other Atopobathynella taxa sequenced by 12 S = 30.4 – 38 % (Appendix 3, COI sequence was not used to calculate the p-distance as too short).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF90FFFC53BB06AAFAE0F9A9.taxon	description	Description female holotype (WAMC 78933). Body length of 1.08 mm. Body eight and a half times as long as maximum width, elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of body. Antennula (Fig. 16 A): six-segmented, with articles rectangular. The first three articles are similar in length and 0.25 times longer that the remaining three, which are similar in length. Inner flagellum small, with three setae. Plumose setae absent in the internal angle of the distal end of the fourth segment, two typical outer plumose setae located on small protuberance, one short and one long, extending beyond the distal end of the fifth article. Ventral seta present in articles two and three. Articles five and six with three terminal aesthetascs each, similar in length on fifth article, and two long and one short on sixth article. Antennular setation as in Fig. 16 A. Antenna (Fig. 16 B): one-segmented with three smooth setae, two terminal and one subterminal. Labrum (Fig. 16 C): slightly convex, free edge with 16 teeth, seven on each side and two central ones. Paragnaths: absent. Mandible (Fig. 16 D): pars incisiva with three teeth; pars molaris with five claws, the most distal one modified with three pronounced distal teeth, thicker and separated from the rest, two most proximal claws joined together; tooth on ventral edge present and small. Mandibular palp with one distal seta (broken). Maxillula (Fig. 16 E): proximal endite with four unequal claws; distal endite with five claws, the two distal smooth and the other three denticulated, the most basal one thinner than the rest; three smooth subterminal setae on the outer distal margin. Maxilla (Fig. 16 F): four-segmented, setal formula 2, 4, 11, 1. Thoracopods I to VII (Figs. 17 A – G): length slightly increasing from thoracopod one to five, decreasing from ThVI to VII. Epipod present in thoracopods II to VII (epipods of ThII of holotype broken, but present in the paratype WAMC 78932), of similar length to two-thirds of the corresponding basipod. All basipods with one distolateral seta as long as the first article of the endopod. Exopod one-segmented in all thoracopods, exopod of ThI, II and VII (Fig. 12 A, B, G) slightly shorter than the distal end of the second article of the endopod, exopod of ThIII and IV (Fig. 12 C, D) slightly longer than the distal end of the second article of the endopod, exopod of ThVI (Fig. 12 F) as long as the first two articles of the endopod; exopod of ThI with two distal setae, the outer one very short. Exopod of ThII to VII bearing three barbed setae, the two terminal ones of different length, with the outer one very short, about half the length of the subterminal seta. Endopod four-segmented, first article short, half the length of the second and third article, with one seta on ThI, and no seta on the other thoracopods; second and third articles long and similar in length in all thoracopods; second article with one outer plumose seta in all thoracopods, and one inner smooth seta on ThI only; third article with one inner seta on ThI only, and one very small outer seta on other thoracopods; fourth article very reduced with two strong claws of different length on thoracopod I and only one long strong claw on ThII to VII. Setal formula of endopods as follows: ThI 1 + 0 / 1 + 1 / 1 + 0 / 2 ThII to VII 0 + 0 / 0 + 1 / 0 + 1 / 1 Thoracopod VIII (Figs. 16 G): very small, like a “ little finger ”. Pleopod I (Figs. 16 H): one long plumose seta located on the anterior third of the first segment of the pleon on both sides. Uropod (Fig. 17 H): sympod about four times as long as wide, and four times the length of the exopod and endopod, with seven (eight on the other side) inhomonomous spines, with the distal one bigger than the others, occupying the distal half of the sympod. Exopod with two terminal setae of different length (one barbed), and one long barbed basal seta. Endopod distally drawn out into a long dagger-shaped structure as long as the exopod, distolateral angle bearing one barbed and one smooth setae of different length, one reaching the distal end of dagger-shaped structure, and one twice as long. Pleotelson (Fig. 17 I): with triangular anal operculum protruded. Lateral seta very short. Furca (Fig. 17 I): rami robust and trapezoidal, with five barbed spines; three basal ones smaller than the two distal ones; distal spine thicker than the others. Two dorsal plumose setae of different lengths, the inner one reaches the end of the distal spine and the outer one is twice as long as the inner seta.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF90FFFC53BB06AAFAE0F9A9.taxon	distribution	Distribution and remarks. Atopobathynella rudini has been collected from one site at the Boolgeeda Creek (a tributary of the Ashburton River), in the hyporheic habitat (Fig. 1). Atopobathynella rudini sp. nov. does not have any unique characters that distinguish it from all the others, however its combination of characters is unique (Appendix 5). It has a protruded anal operculum (Fig. 17 I), a character found in only five other species of the genus: A. schminkei (from Australia), A. compagana (from New Zealand), and three Indian species. This species was previously known by Biologic Environmental Surveys as Atopobathynella sp. “ Biologic-PBAT 014 ”. Despite being collected geographically close to the site where A. abelloana sp. nov. occurs (Fig. 1), this species is genetically distant to A. abelloana sp. nov. and to all other putative species of Atopobathynella sequenced so far (Fig. 5).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF90FFFC53BB06AAFAE0F9A9.taxon	etymology	Etymology. The name of the species is dedicated to Fabian Rudin, one of the collectors of this species.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF95FFE653BB039AFCFEFDD3.taxon	description	(Figs. 18 – 19)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF95FFE653BB039AFCFEFDD3.taxon	materials_examined	Material examined. Holotype male. AUSTRALIA: Western Australia: Rhodes Ridge, Pilbara, karaman RRWON 54, 23 ° 7 ' 11.2152 " S, 119 ° 4 ' 43.0422 " E, 12 February 2021, P. Runham, A. Mittra (WAMC 82071 — BES 10623 — BMR 03982, permanent slide). Paratypes: AUSTRALIA: Western Australia: 1 female (WAMC 82073 — BES 11526 b, permanent slide) and 1 male (WAMC 82074 — BES 11526 c, permanent slide), same detail as holotype; 1 female, Rhodes Ridge, Pilbara, karaman RRWONKC 050, 23 ° 5 ' 2.6586 " S, 119 ° 9 ' 20.3436 " E, 7 February 2021, P. Runham, A. Mittra (WAMC 82066 — BES 10831 — BMR 03989, permanent slide); 1 female, Rhodes Ridge, Pilbara, karaman RRWONKC 051, 23 ° 05 ' 20.8400 " S, 119 ° 08 ' 12.8958 " E, 9 February 2021, P. Runham, A. Mittra (WAMC 82068 — BES 10703 — BMR 04001, permanent slide); 1 male (WAMC 82070 — BES 11621 a, permanent slide), details as above; 1 male, Gudai Darri, Pilbara, Bore MB 19 K 58 W 0001, 22 ° 31 ' 52.1862 " S, 119 ° 0 ' 20.0772 " E, 10 June 2021, C. Norris, F. Rudin, (WAMC 76664 — BES 12768 — BMR 03941, permanent slide); 1 female (WAMC 76677 — BES 10454 — BMR 03369, permanent slide) details as above; 1 male Gudai Darri, Pilbara, Bore 200 NB 13768, 22 ° 30 ' 45.5004 " S, 119 ° 1 ' 16.9422 " E, 10 June 2021, S. Paget, J. Huey, (WAMC 76679 — BES 11525 — BMR 02766, permanent slide); 1 female Gudai Darri, Pilbara, Bore MB 21 G 101 W 0002, 22 ° 28 ' 18.1272 " S, 118 ° 53 ' 57.0978 " E, 17 September 2022, F. Rudin, A. Umbrello, (WAMC 78944 — BES 17446 — BMR 05155, permanent slide; 1 male West Angelas, Pilbara, bore at 23 ° 08`31.01 " S, 118 ° 39`17.67 " E, 21 March 2016, S. Callan, E. S. Volschenk, (WAMC 78973, permanent slide); 1 female (WAMC 78974, permanent slide), same detail as above; 1 male West Angelas, Pilbara, bore at 23 ° 08`31.53 " S, 118 ° 38`47.74 " E, 16 March 2016, S. Callan, E. S. Volschenk, (WAMC 78976, permanent slide); 1 male (WAMC 78977, permanent slide) same detail as above; 1 female Yandi Creek, Pilbara, karaman at 22 ° 47 ' S, 119 ° 9 ' E, 20 April 2022, A. Riemer, I. Johansson, (WAMC 82076 — BES 15605 — BMR 05460, permanent slide); 1 female, Yandi Creek, Pilbara, karaman at 22 ° 43 ' S, 118 ° 57 ' E, 11 September 2022, J. Delaney, S. Rodman, C. Wilkins, (WAMC 82078 — BES 22638 a, permanent slide); 1 male (WAMC 82079 — BES 22638 b, permanent slide), same details as above. Additional material: AUSTRALIA: Western Australia: 49 specimens in alcohol, West Angelas, Pilbara, bore at 23 ° 08`31.01 " S, 118 ° 39`17.67 " E, 21 March 2016, S. Callan, E. S. Volschenk, (WAMC 70169); 91 specimens in alcohol, West Angelas, Pilbara, bore at 23 ° 08`31.53 " S, 118 ° 38`47.74 " E, 16 March 2016, S. Callan, E. S. Volschenk, (WAMC 70170); 1 juvenile in alcohol, Rhodes Ridge, Pilbara, karaman RRWONKC 050, 23 ° 5 ' 2.6586 " S, 119 ° 9 ' 20.3436 " E, 7 February 2021, P. Runham, A. Mittra (WAMC 82067 — BES 11534); 3 juveniles, 1 female in alcohol, Rhodes Ridge, Pilbara, karaman RRWONKC 051, 23 ° 05 ' 20.8400 " S, 119 ° 08 ' 12.8958 " E, 9 February 2021, P. Runham, A. Mittra (WAMC 82069 — BES 11621); 56 specimens in alcohol, (WAMC 82072 — BES 11526), same detail as holotype; 1 juvenile in alcohol, Rhodes Ridge, Pilbara, karaman RRGINKARA 01, 23 ° 09 ' 45.7424 " S, 119 ° 01 ' 04.0861 " E, 9 February 2021, P. Runham, A. Mittra (WAMC 82075 — BES 12774 — BMR 03955); 1 female in alcohol, Yandi Creek, karaman at 22 ° 43 ' S, 118 ° 56 ' E, 1 April 2023, J. Delaney, K. Nguyen, S. Paget (WAMC 82077 — BES 19803 — BMR 08587); 1 male, 5 female, 5 juveniles in alcohol, Yandi Creek, Pilbara, karaman at 22 ° 43 ' S, 118 ° 57 ' E, 11 September 2022, J. Delaney, S. Rodman, C. Wilkins, (WAMC 82080 — BES 22638).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF95FFE653BB039AFCFEFDD3.taxon	diagnosis	Diagnosis. Atopobathynella pervulgata sp. nov. belongs to a group of Atopobathynella species that have antennal organ (AO) without protuberance, with one long and strong seta that reaches over half of the length of article four; distal endite of maxillula with five claws; sympod of the uropod with inhomonomous spines; exopod of the uropod with two distal setae. It differs from the rest of Atopobathynella species by the presence of only six pairs of thoracopods. The sequenced specimens differ from all the other Atopobathynella species sequenced by COI = 11.2 – 20.5 % and 12 S = 11.4 – 37.2 % (Appendices 3, 4). The COI intraspecific variation ranges between 0 – 7.9 % (Supplementary Material Table S 1), with average 5.1 % (Appendix 2). The 12 S intraspecific variation ranges between 0 – 7.5 % (Supplementary Material Table S 2), with average 4.2 % (Appendix 3).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF95FFE653BB039AFCFEFDD3.taxon	description	Description male holotype (WAMC 82071). Body length of 0.9 mm. Body about nine times as long as maximum width, elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of the body. Antennula (Fig. 18 A): six-segmented. Articles wide, gradually shortening and thinning from article one to six, with article six half as wide as the first two. Antennal organ represented by one long and thick ventral seta which reaches half the length of article four. Inner flagellum small with three setae. Ventral seta present in article two and three. Plumose seta present on the inner distal end of article four, in addition to the two typical outer plumose setae on protuberances on the outer corner of article four, one short and one extending beyond the distal end of the fifth article. Articles five and six with three terminal aesthetascs each, one slightly longer on article five, and two long and one shorter on article six. Antennular setation as in Fig. 18 A. Antenna (Fig. 18 B): one-segmented with four setae, two terminal and one subterminal smooth, and one terminal plumose seta. Labrum (Fig. 18 C): slightly concave, free edge with 16 teeth, seven long teeth on each side, and two central small triangular ones. Paragnaths: absent. Mandible (Fig. 18 D): pars incisiva with three teeth; pars molaris with five claws, the most distal one slightly modified and separated from the rest, the two most proximal claws joined together; tooth on ventral edge very small. Mandibular palp with one distal seta that reaches the distal end of the pars molaris. Maxillula (Fig. 18 E): proximal endite with four unequal claws, two thick with denticles and two thinner; distal endite with five claws, two distal ones smooth, three proximal ones with some spines; three smooth subterminal setae on the outer distal margin. Maxilla (Fig. 18 F): four-segmented, setal formula 2, 4, 12, 1. Thoracopods I to VI (Figs. 18 G and 19 A – E): length slightly increasing from thoracopod one to four, the last two thoracopods similar in length. Epipod present in ThII to VI, with length about half the corresponding basipod. All basipods with one distolateral seta slightly shorter than the first article of the endopod (except in ThI). Exopod one-segmented in all thoracopods; exopod of ThI (Fig. 18 G) and II (Fig. 19 A) reaching the distal end of the second article of the endopod; exopod of ThIII to VI (Fig. 19 B – E) slightly longer than the first two articles of the endopod. Exopod of all thoracopods bearing three setae, two terminal ones of different length, with the outer smooth seta half of the length of the barbed subterminal seta, barbed inner seta not reaching the distal end of the claws of the endopod in ThI, while it extends beyond the distal claw of the endopod, progressively increasing in length from ThII to VI. Endopod four-segmented, first article short, half the length of the second and third article, with one seta on thoracopod I, and no seta on the rest of thoracopods; second and third articles long, second article slightly longer than the third one in all thoracopods; second article with one outer plumose seta in all thoracopods and two smooth inner setae on ThI only; third article with one inner seta on ThI and one small outer seta on the rest of thoracopods; fourth article very reduced with two strong claws of different length on ThI and only one long strong claw on ThII to VI. Setal formula of endopods as follow: ThI 1 + 0 / 2 + 1 / 1 + 0 / 2 ThII to VI 0 + 0 / 0 + 1 / 0 + 1 / 1 Thoracopod VIII (Figs. 18 H): compact, like a balloon. Penial region with massive protopod, outer lobe oval shape, reaching the distal end of basipod, well defined at base in latero-external view. Inner lobe small, finger shape. Dentate lobe with seven teeth. Basipod without delimited base, with a projection and a seta of uncertain origin. Pleopod I (Fig. 19 H): one smooth seta on each side. Uropod (Fig. 19 F): sympod about 3 times as long as wide, about 3.5 times the length of the exopod and about six times the length of endopod, with six uneven spines, increasing in length from the proximal to the distal spine and occupying two thirds of the sympod. Exopod with two very long barbed terminal setae of similar length, and one basal plumose seta as long as exopod. Endopod distally drawn out into a very long dagger-shaped structure longer than the exopod, with distolateral angle bearing two setae, one outer barbed a third longer than the plumose inner one and almost twice the length of the dagger-shaped structure. Pleotelson (Fig. 19 G): anal operculum not protruded, short lateral seta. Furca (Fig. 19 G): rami robust and almost square, with four barbed spines, three distal ones of similar length and the basal one two thirds of the others. Two dorsal plumose setae, inner seta very short, and the outer seta more than twice the length of the distal spines. Female paratype differs from male in the second antennular segment (Fig. 18 I) that bears no antennal organ, and ThVIII, which is very small and tooth / denticle shaped (Fig. 18 J). Variability. Variability was observed in body size (males 0.78 – 1.1 mm and females 0.6 – 1.07 mm); number of teeth on labrum (16 – 22); number of setae on exopod of the ThI (2 or 3) and number of setae on exopod of the ThV – VI (2 or 3); number of inner setae on the second article of ThI (1 or 2); length of setae on distolateral angle of the endopod of the uropod (2 short, 2 long, 1 long and 1 short); and number of spines on sympod of uropod (5 – 11). One specimen (WAMC 76679) has endopod and exopod of uropod deformed (see Supplementary Material Fig. S 2).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF95FFE653BB039AFCFEFDD3.taxon	distribution	Distribution and remarks. Atopobathynella pervulgata sp. nov. has been recorded from three bores from the Gudai Darri area (south Hamersley Range), four sites in the hyporheic habitat near Yandy Creek, four sites in the hyporheic habitat south of the Weeli Wolli Creek, and two bores at West Angelas (Figs. 1, 20), which represent four disconnected aquifers. This species was previously known by Biologic Environmental Surveys as Atopobathynella sp. “ Biologic-PBAT 019, PBAT 029, PBAT 030, PBAT 042, and PBAT 054 ”. Despite being collected in several sites geographically closer to eight other Atopobathynella species (see Fig. 20), our results indicate that Atopobathynella pervulgata isgenetically closest to A. degreyensis, collected in the De Grey River Catchment, 250 km northeast (Figs. 1, 5). This is the first example of relatively wide distribution (about 80 km) of Parabathynellidae species in the Pilbara, and the first case of Atopobathynella species with only six pairs of thoracopods.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF95FFE653BB039AFCFEFDD3.taxon	etymology	Etymology. The name of the species derives from the Latin word “ pervulgata ” (singular, feminine) meaning widespread, which refers to the distribution of this species. Genus Kimberleybathynella Cho, Park & Humphreys, 2005	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF95FFE653BB039AFCFEFDD3.taxon	type_taxon	Type species: Kimberleybathynella gigantea Cho, Park & Humphreys, 2005 Other species: see Table 7.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF95FFE653BB039AFCFEFDD3.taxon	diagnosis	Amended diagnosis (after Cho, Park & Humphreys, 2005). Body elongated and cylindrical. Antennula six-segmented. Antenna two-segmented. Labrum flat. Maxilla four-segmented, second and third segments of maxilla half-fused. Exopod of thoracopods I – VII one-segmented. Male thoracopod VIII hemispherical, protopodite protruded, basipod without setae, inner margin of basipod drawn out into projection. Distal spine of uropodal sympod longer and thicker than other spines. Uropodal exopod bearing two terminal setae, of which the outer seta is longer than inner one.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF8FFFE553BB073CFAE8F82A.taxon	description	(Figs. 21 & 22)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF8FFFE553BB073CFAE8F82A.taxon	materials_examined	Material examined. Holotype male. AUSTRALIA: Western Australia: Ord River, Kimberley, Bore T 4 GRC 225 (pump sample), 17 ° 35 ' 45.7525 " S, 127 ° 55 ' 43.4766 " E, 28 April 2017, S. Callan, M. O’Connell (WAMC 79094 — BES 2156 b — BMR 8555, permanent slide). Paratypes: AUSTRALIA: Western Australia: 1 female, (WAMC 79095 — BES 2156 b, in alcohol), same details as holotype; 1 female, Ord River, Kimberley, Bore T 6 GRC 210 (pump sample), 17 ° 36 ' 34.3106 " S, 127 ° 57 ' 46.6114 " E, 27 April 2017, S. Callan, M. O’Connell (WAM C 79096 — BES 2132 b — BMR 8556 permanent slide); 1 female, Ord River, Kimberley, Bore T 4 GRC 216 east (pump sample), 17 ° 35 ' 47.3238 " S, 127 ° 55 ' 39.0822 " E, 25 April 2017, S. Callan, M. O’Connell (WAMC 79092 — BES 1956 b — BMR 08554, permanent slide); 1 male, Ord River, Kimberley, Bore T 4 GRC 240 (pump sample), 17 ° 36 ' 19.8003 " S, 127 ° 54 ' 55.1952 " E, 25 April 2017, S. Callan, M. O’Connell (WAMC 79097 — BES 2194 b — BMR 8558, permanent slide); 1 female (WAMC 79098 — BES 2194 b — BMR 8559, permanent slide), same details as above; 1 male (WAMC 79009 — BES 2194 b, permanent slide), same details as above; 1 female (WAMC 790010 — BES 2194 b, permanent slide), same details as above; 1 specimen (sex not available) (WAMC 790011 — BES 2194 b, permanent slide), same details as above. Additional material AUSTRALIA: Western Australia: 1 female, Ord River, Kimberley, Bore T 4 GRC 216 east (pump sample), 17 ° 35 ' 47.3238 " S, 127 ° 55 ' 39.0822 " E, 25 April 2017, S. Callan, M. O’Connell (WAMC 79093 — BES 1956 b, in alcohol); 3 males, 3 females, Ord River, Kimberley, Bore T 4 GRC 240 (pump sample), 17 ° 36 ' 19.8003 " S, 127 ° 54 ' 55.1952 " E, 25 April 2017, S. Callan, M. O’Connell (WAMC 79099 — BES 2194 b, in alcohol).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF8FFFE553BB073CFAE8F82A.taxon	diagnosis	Diagnosis. Kimberleybathynella ordensis sp. nov. belongs to a group of Kimberleybathynella species that have a square inner flagellum on antennula; tooth of ventral edge present but small; distal endite of maxillula with six claws; epipod of thoracopod I present; three setae on exopod of thoracopods II to VII; one pair of setae on pleomeres I to V; three setae on exopod and two setae on endopod of uropod; anal operculum not protruded. K. ordensis sp. nov. differs from other congeners by having five teeth in the pars molaris of the mandible (Appendix 6). The sequenced specimens differ from all the other Kimberleybathynella species sequenced by COI = 18.9 – 25.2 % (Table 3) and 12 S = 17.6 % (S. E. = 0.4 %) with K. callani sp. nov..	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF8FFFE553BB073CFAE8F82A.taxon	description	Description male holotype (WAM C 79094). Body length of 1.61 mm. Body about ten times as long as maximum width, elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of body. Antennula (Fig. 21 A): six-segmented. First three articles gradually shorter and thinner, fourth and fifth articles similar in length and slightly shorter than the first three articles, last article slightly longer than article four and five and shorter than the first three articles. Antennal organ absent. Inner flagellum small, almost square. Article five and six respectively with two and three aesthetascs. Antennula setation as in Fig. 21 A. Antenna (Fig. 1 B): two-segmented, as long as the first article of the antennula; first article rectangular, without setae, second article with one subterminal seta and three terminal setae, two smooth of different length and one long terminal plumose seta. Labrum (Figs. 21 C): slightly convex, 18 main teeth on free edge, eight on each side and two tridentate central teeth. Rows of spinules in ventral surface. Paragnaths: absent. Mandible (Fig. 21 D, G): pars incisiva with three teeth; pars molaris with five denticulate claws, with the two most proximal ones joined together; tooth of ventral edge small and triangular. Mandibular palp with a small article with one long distal seta reaching beyond pars molaris, but not exceeding pars incisiva. Maxillula (Fig. 21 E): proximal endite with four unequal claws; distal endite with four denticulated claws and two smooth ones; three smooth subterminal setae on the outer distal margin, one of which is almost half the length of the other two. Maxilla (Fig. 21 F): four-segmented, first and second articles partially fused, setal formula 2, 4, 15, 1. Thoracopods I to VII (Figs. 22 A – G): length gradually increasing from ThI to III, last four similar in size. Epipod present in all thoracopods, about 1 / 3 length of the corresponding basipod. All basipods with one smooth, distolateral seta shorter than the first article of the endopod in ThI to IV and VII, and of the same length as the first article in ThV and VI. Exopod one-segmented in all thoracopods; exopod of ThI shorter than the first two articles of the corresponding endopod, exopod similar in length to the first two articles of the endopod in ThII to VII; exopod with three barbed setae, one subterminal slightly longer than the outer terminal seta in ThI to IV and VII, and twice as long in ThV and VI; and two terminal setae, with the internal one two times longer than the external in ThI, three times longer in ThII, four times longer in ThIII, IV and VII and five times longer in ThV and VI; the internal seta of the exopod extends beyond the distal end of the claws of the fourth article of the endopod in ThIII to VII. Endopod four-segmented, first article short with one seta on ThI and no seta on the rest of the thoracopods, second and third articles long and similar in length; second article with one plumose external seta in all thoracopods, and two inner smooth setae only on ThI; third article of ThI with one small inner seta, and one outer seta on ThII to VII; fourth article very reduced with two strong claws of different length on all thoracopods, ThI with one additional seta. Setal formula of endopods: ThI 1 + 0 / 2 + 1 / 1 + 0 / 3 (1) ThII to VII 0 + 0 / 0 + 1 / 0 + 1 / 2 Thoracopod VIII (Figs. 21 H, I): compact, balloon-shaped. Penial region with massive protopod, outer lobe triangular and defined at base in latero-external view; exopod triangular with a terminal spine, endopod denticulated, similar in size to exopod; basipod with inner distal end rounded over-reaching the outer lobe, without seta. Pleomeres I – V (Fig. 22 H): one seta on each side. Uropod (Fig. 22 I): sympod over three times the length of the endopod (excluding the dagger- shaped structure) and almost three times as long as wide, with nine subequal spines. Endopod almost as long as exopod, with internal row of small “ spinules ” in the middle and drawn out distally into a dagger-shaped structure with terminal setules, and with distolateral angle bearing two barbed setae of similar length. Exopod with two terminal barbed setae (inner one shorter), and one short basal seta. Pleotelson: with one small plumose lateral seta (one on each side); anal operculum not protruded. Furca (Fig. 22 J): each ramus trapezoidal, with five barbed spines which increase in length from the proximal to the distal one, which is three times longer than the proximal one. Two dorsal plumose setae on each ramus, the inner one very short and the outer one exceeds the tip of distal spine. Female paratype differs from male in the thoracopod VIII (Fig. 21 J), which is a bulge with a tooth-like projection. Variability. Variability was observed in body size (1.03 to 1.75 mm in females and 0.92 to 1.61 mm in males); number of teeth on labrum (14 – 18); number of teeth on pars distalis of mandible (3 – 4), in one female (WAMC 79096), the proximal claw of the pars molaris of mandible is bifurcated, number of setae on exopod of ThI, VI and VII (2 or 3); number of spines on sympod (8 to 13).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF8FFFE553BB073CFAE8F82A.taxon	distribution	Distribution and remarks. K. ordensis sp. nov. has been collected from four bores about 15 km south of the Ord River, in the Kimberley (Fig. 2). The distribution could possibly extend beyond these four bores (Biologic Environmental Surveys unpublished data), however all material collected in the area was not available for this study. This species was previously identified as K. pleochaeta as it shares many characters with this species, however it differs from it by the number of aesthetascs on article five of the antennula, number of teeth on labrum, and number of spines on furca (Appendix 6). Unfortunately, the male of K. pleochaeta is unknown, and molecular data are not available, therefore, a full comparison is not possible. Nevertheless, we believe that the differences listed above, together with the geographical distance (K. pleochaeta was collected about 100 km northeast, Fig. 2) are enough to establish a new species.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF8FFFE553BB073CFAE8F82A.taxon	etymology	Etymology. The name of the species is derived from the Ord River, which is close to the type locality.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF83FFE953BB05CBFE8DF9C1.taxon	description	(Figures 23 & 24)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF83FFE953BB05CBFE8DF9C1.taxon	materials_examined	Material examined. Holotype male. AUSTRALIA: Western Australia: Ord River, Kimberley, Murrays Bore (pump sample), 17 ° 38 ' 43.6374 " S, 127 ° 55 ' 40.0584 " E, 3 November 2016, S. Callan, M. O’Connell, (WAMC 79091 — BES 2077 b — BMR 08553, permanent slide).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF83FFE953BB05CBFE8DF9C1.taxon	diagnosis	Diagnosis. K. callani sp. nov. belongs to a group of Kimberleybathynella species that have inner flagellum on antennula very small; tooth of ventral edge of mandible absent; distal endite of maxillula with six claws; epipod of thoracopod I present; two setae on exopod of thoracopods I to VII; two setae on exopod and endopod of uropod; anal operculum not protruded. K. callani sp. nov. differs from all the other Kimberleybathynella by having two setae on all exopods of the thoracopods and no ventromedial seta on the exopod of the uropod. The sequenced specimen differs from all the other Kimberleybathynella species sequenced by COI = 18.9 – 25.1 % (Table 3) and 12 S = 17.6 % (S. E. = 0.4 %) with K. ordensis sp. nov.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF83FFE953BB05CBFE8DF9C1.taxon	description	Description male holotype (WAM C 79091). Body length of 0.76 mm. Body eight and a half times as long as maximum width, elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of body. Antennula (Fig. 23 A): six-segmented. The first, second and sixth articles similar in length and 1 / 4 longer than the other three, which are similar in length. Antennal organ absent. Very small inner flagellum almost, rectangular. Article five and six with three terminal aesthetascs each. Antennula setation as in Fig. 23 A. Antenna (Fig. 23 B): two-segmented, longer than the first article of the antennula; first article square without setae, second article with one smooth subterminal and three terminal setae, of which two smooth of different length and one plumose which is the longest. Labrum (Figs. 23 C): almost flat, with 15 main teeth on free edge, six and seven on each side, and two centrals. Paragnaths: absent. Mandible (Fig. 23 D): pars incisiva with three teeth; pars molaris with five claws, with the two distal ones denticulate and the two proximal ones joined together; tooth of ventral edge absent. Mandibular palp with a very small article with one long distal seta not exceeding pars incisiva. Maxillula (Fig. 23 E): proximal endite with four unequal claws; distal endite with four denticulated claws and two smooths; three smooth subterminal setae of different lengths on the distal outer margin. Maxilla (Fig. 23 F): four-segmented, first and second articles partially fused, setal formula 2, 3, 11, 1. Thoracopods I to VII (Fig. 24 A – G): length gradually increasing from ThI to III, last four similar in size. Epipod present in thoracopods I to VII about 2 / 3 length of the corresponding basipod. Basipods with one smooth, distolateral seta shorter than the first article of the endopod in ThI to II and longer than the first article of the endopod in ThIII to VII. Exopod one-segmented in all thoracopods, shorter than corresponding two first articles of the endopod in all thoracopods, with two barbed terminal setae, with the internal one slightly longer than the external one in ThI, three times longer in ThII and VI, two times longer in ThIII to V, and two and half times longer in VII; internal seta of the exopod extending beyond the distal end of the fourth article of the endopod in ThIII to VII. Endopod four-segmented, first article short with one seta on ThI and no seta on the rest of thoracopods, second and third articles long and similar in length; second article with one plumose external seta in all thoracopods and one inner smooth seta only on ThI; third article of ThI with one small inner seta, and one outer seta on ThII to VII; fourth article very reduced with two strong claws of different length on all thoracopods, ThI with one additional seta. Setal formula of endopods: ThI 1 + 0 / 1 + 1 / 1 + 0 / 3 (1) ThII to VII 0 + 0 / 0 + 1 / 0 + 1 / 2 Thoracopod VIII (Figs. 23 G, H): compact, rectangular shape. Penial region with massive protopod, outer lobe rectangular and defined at base in latero-external view; exopod almost square with small teeth on distal end and not defined at base, endopod rounded with one seta, similar in size to exopod, endopod and exopod integrated in basipod; basipod not defined at base, with inner distal end rounded not reaching the outer lobe. Pleopod I: not seen. Pleopods II to V: unknown, segments used for DNA extraction. Uropod (Fig. 24 H): sympod over three times the length of the endopod (excluding the dagger-shaped structure) and almost six times as long as wide, with eight spines, the most distal one slightly longer than others. Endopod almost as long as exopod, with internal row of small “ spinules ” in the middle, drawn out distally into a long dagger-shaped structure with terminal setules, and with distolateral angle bearing two barbed setae of different length. Exopod with two terminal barbed setae (inner one shorter) and no ventromedial seta. Pleotelson (Fig. 24 I): with two very small plumose lateral setae (one on each side); anal operculum not protruded. Furca (Fig. 24 I): each ramus almost square, with four barbed spines which increase in length from the proximal to the distal one, which is two times longer than the first. Two dorsal plumose setae on each ramus, the inner one very short and the outer one exceeds the tip of the most distal spine. Female of K. callani is unknown.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF83FFE953BB05CBFE8DF9C1.taxon	distribution	Distribution and remarks. K. callani sp. nov. has been collected from one bore about 18 km south of the Ord River, in the Kimberley (Fig. 2). The distribution could possibly extend beyond Murrays bore (Biologic Environmental Surveys unpublished data), however all material collected in the area was not available for this study. This species is similar to K. pleochaeta and K. ordensis sp. nov., however it differs from them by the number of setae on the exopod of thoracopods (only two), the number of spines on furca (four), and the absence of a ventromedial seta on the exopod of the uropod. K. callani sp. nov. is the only species that does not have the “ tooth ventral edge ” between the pars molaris and pars distalis of the mandible (Fig. 23 D), male ThVIII rectangular instead of hemispherical, ventro-medial seta of uropodal exopod absent. Unfortunately, the body segments of the pleon were used for DNA extraction, so it was not possible to determine if it had additional pleopods on pleomere II to V. K. callani sp. nov. was collected about six km south from K. ordensis sp. nov. (Fig. 2) and the two species are sister taxa in the molecular phylogeny (Fig. 5).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF83FFE953BB05CBFE8DF9C1.taxon	etymology	Etymology. The name of the species is dedicated to Shae Callan, one of the collectors of the species and a colleague. Genus Hexabathynella Schminke, 1973	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF83FFE953BB05CBFE8DF9C1.taxon	type_taxon	Type species. Hexabathynella pauliani (Delamare Deboutteville, 1953). Parabathynella valdiviana Delamare Deboutteville, 1953 Other species: see Table 7	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF83FFE953BB05CBFE8DF9C1.taxon	diagnosis	Amended diagnosis (after Cho and Schminke 2006). Body elongated and cylindrical. Antennula six-segmented. Second antennular segment sexually dimorphic. Antenna five-segmented. Labrum flat. Pars molaris of mandible consisting of five spines. Maxilla three-segmented. Thoracopod VII absent. Exopod of thoracopod I one-segmented; that of thoracopods II – VI one or two-segmented. Male thoracopod VIII massive, basipod bearing a seta and being drawn out in a chitinous projection, with elongated endopod and triangular or square exopod. Endopod with one or two distal setae. Sympod of uropod with spines: distal spine longer than other spines. Inner terminal seta of uropodal exopod shorter than outer one. Furcal rami with three spines.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF80FFEC53BB0332FB35F849.taxon	description	(Figs. 25 to 26)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF80FFEC53BB0332FB35F849.taxon	materials_examined	Material examined: Holotype female. AUSTRALIA: Western Australia: Miralga Creek, Pilbara Bore ALB 0004 (stygofauna net haul) 20 ° 45 ' 05.8217 " S, 119 ° 19 ' 20.2570 " E, 7 November 2019, F. Rudin, M. Lythe. (WAMC 78876 — BES 8281, permanent slide). Paratypes: 1 female (WAMC 78877 — BES 7328, uropods and furcal rami on permanent slide, rest of the body used for DNA), same details as holotype. This specimen was missing the head when collected.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF80FFEC53BB0332FB35F849.taxon	diagnosis	Diagnosis: H. miralgaensis sp. nov. belongs to a group of Hexabathynella species small (0.75 – 0.9 mm); with three teeth on pars incisiva and five on pars molaris of mandible; epipod present on thoracopods III to VI; sympod with five inhomonomous spines, with distal spine much longer than the others; exopod and endopod of uropod with two setae, with exopod longer than the endopod. Similarities and differences with other Hexabathynella species are listed in Appendix 7. Unfortunately, males of this species were not collected. The sequenced specimens differ from all the other Hexabathynella species sequenced by COI = 17.7 – 21.9 % and 12 S = 21.9 – 23 % (Tables 4, 5).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF80FFEC53BB0332FB35F849.taxon	description	Description: body length of females 0.75 – 0.9 mm (holotype 0.75 mm). Body elongated, eight and a half times as long as maximum width, almost cylindrical, segments slightly widening towards the posterior end of the body. Antennula (Figure 25 A): six-segmented. First and second articles similar in width, combined length similar to the length of the third, fourth and fifth articles together, with second article the longest, followed by first, third, and sixth, fifth article is the shortest followed by the fourth. Inner flagellum small, almost square. Article five and six with three terminal and three subterminal aesthetascs respectively. Setation as Fig. 25 A. Antenna (Figure 25 B): five-segmented, distal article longest, fourth article slightly shorter and equal to the other three combined. Articles one to three with no setae. Article three with two setae and article five with three setae, with the shortest plumose. Labrum (Fig. 25 C): broken, with at least 10 teeth. Mandible (Fig. 25 D): pars incisiva with three teeth, pars molaris with five teeth, with the two most proximal ones joined together and covered in fine setules; tooth of ventral edge triangular. Mandibular palp with one distal seta reaching beyond the distal end of the pars incisiva. Paragnaths (Fig. 25 G): presence of a rounded structure, with small spines on the distal end that could possibly support paragnaths, in this case absent. Maxillula (Fig. 25 F): proximal endite with four distal claws of different size, two longer and two shorter; distal endite with six claws, the four proximal with denticles; three smooth subterminal setae on the outer distal margin. Maxilla (Fig. 25 F): four-segmented, with short setae, setal formula 2, 4, 9, 1. Thoracopods I to VI (Figs. 25 H, I and 26 A – D): length gradually increasing from thoracopod one to four, last two similar in size. Epipod present from Th III to VI, about one-half of the length of the corresponding basipod. Basipod of Th I and II (Fig. 25 H, I) with one short, smooth, distolateral seta, absent in ThIII to VI (Fig. 26 A – D). Exopod one-segmented and shorter than the first two articles of endopod in thoracopod I; two-segmented in ThII to VI with the first article similar in in length or longer than the first two articles of the endopod; exopod of ThII to VI similar or slightly shorter than endopod. First exopodal article of ThII to VI with two setae, one of which barbed. Endopod four-segmented, first article short, second and third articles similar in length and slightly longer than the first one; fourth segment reduced with two long claws on ThI, and one smooth long claw on thoracopods II to VI; outer plumose seta on second article of ThI – VI. Setal formula of endopods: ThI 1 + 0 / 0 + 1 / 1 + 0 / 2 ThII to VI 0 + 0 / 0 + 1 / 0 + 0 / 1 Thoracopod VIII female: absent Pleopod (Fig. 26 E): one smooth seta. Uropod (Figure 26 F): sympod short, about twice as long as wide, with five inhomonomous spines occupying the distal third of the sympod, distal spine two times longer than others and longer than the exopod; exopod almost a third longer than endopod, with two terminal setae of different length; distolateral angle of the endopod bearing two similar setae slightly longer that the tip of the article. Pleotelson (Figure 26 G, H): with two lateral setae of different length on each side; anal operculum protruded. Furca (Figure 26 G, H): each ramus almost square, with three barbed spines of different sizes, basal spine shortest. Two dorsal setae similar in size exceeding the distal spine. Variability: was observed in body size (0.75 – 0.9 mm).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF80FFEC53BB0332FB35F849.taxon	distribution	Distribution and remarks: H. miralgaensis sp. nov. was collected from one bore near Miralga creek, in the De Grey River catchment (Fig. 3). It appears genetically distant from all the other Hexabathynella species from Australia, although it occurs about 60 km south of the collection site of H. sp. 24 (Pardoo), in the same river catchment.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF80FFEC53BB0332FB35F849.taxon	etymology	Etymology: the name of the species refers to the Miralga creek, where it was collected.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF84FF9053BB05CBFEA3F849.taxon	description	(Figs. 27 to 28, Appendix 8)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF84FF9053BB05CBFEA3F849.taxon	materials_examined	Material examined: Holotype male. AUSTRALIA: Western Australia: Robe Valley, Pilbara, Bore RC 18 MEK 0211 (stygo net haul) 21 ° 43 ' 42.1018 " S, 116 ° 15 ' 36.5101 " E, 21 September 2021, J. Pille Arnold, S. Rodman. (WAMC 78876 — BES 8281, permanent slide). Paratypes: 1 male, Robe Valley, Pilbara, Bore BC 443 (stygo net haul) 21 ° 57 ' 40.4489 " S, 116 ° 29 ' 13.1366 " E, 11 April 2021, J. Pille Arnold, S. Rodman, (WAMC 78963 — BES 12528 — BMR 05216, permanent slide); 1 female, Robe Valley, Pilbara, Bore BUNWB 13 (stygo net haul) 21 ° 57 ' 04.0981 " S, 116 ° 27 ' 54.8935 " E, 23 September 2021, J. Pille Arnold, S. Rodman (WAMC 78964 — BES 12690 — BMR 05468, permanent slide); 1 female, Robe Valley, Pilbara, Bore BUNWP 0006 (stygo net haul) 21 ° 54 ' 54.1149 " S, 116 ° 24 ' 29.9804 " E, 24 September 2021, J. Pille Arnold, S. Rodman, (WAMC 78965 — BES 12462 — BMR 05469, permanent slide); 1 male, Robe Valley, Pilbara, Bore MB 16 MEH 0016 (stygo net haul) 21 ° 42 ' 48.4313 " S, 116 ° 12 ' 55.7428 " E, 16 August 2022, J. Pille Arnold, S. Rodman, (WAMC 78966 — BES 16291 — BMR 07056, permanent slide); 1 female, Robe Valley, Pilbara, Bore PZ 10 BUN 037 (stygo net haul) 21 ° 50 ' 48.0297 " S, 116 ° 23 ' 42.0475 " E, 20 March 2022, J. Pille Arnold, S. Rodman, (WAMC 78970 — BES 14882 — BMR 07007, permanent slide); 1 male, Robe Valley, Pilbara, Bore YALLWP 01 (stygo net haul) 21 ° 41 ' 29.1726 " S, 116 ° 19 ' 33.6756 " E, 13 August 2022, J. Pille Arnold, S. Rodman, (WAMC 78972 — BES 7934 — BMR 07057, permanent slide); 1 female ,, Robe Valley, Pilbara, Bore MB 18 MEK 0004 (stygo net haul) 21 ° 43 ' 40.2798 " S, 116 ° 15 ' 34.8116 " E, 23 March 2022, M. Curran, M. van Wees (WAMC 78968 — BES 17383 — BMR 07032, in alcohol). Additional material: 1 juvenile, 2 males, (WAMC 78962 — BES 13101, in alcohol), same details as WAMC 78963; 2 females, Robe Valley, Pilbara, Bore MB 18 MEK 0004 (stygo net haul) 21 ° 43 ' 40.2798 " S, 116 ° 15 ' 34.8116 " E, 23 March 2022, M. Curran, M. van Wees (WAMC 78967 — BES 14372, in alcohol); 1 specimen (sex not available) Robe Valley, Pilbara, Bore PZ 09 BUN 016 (stygo net haul) 21 ° 49 ' 58.4930 " S, 116 ° 20 ' 42.3708 " E, 19 March 2022, J. Pille Arnold, S. Rodman, (WAMC 78969 — BES 14470 — BMR 07006, in alcohol).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF84FF9053BB05CBFEA3F849.taxon	diagnosis	Diagnosis: H. julianae sp. nov. belongs to a group of small (0.38 – 0.53 mm) Hexabathynella species; with male antennal organ formed by one modified seta without protuberance; three teeth on pars incisiva and five on pars molaris of mandible; presence of a rounded structure with small spines on the distal end that could represent the support of possible paragnaths, in this case absent; pleopods absent; sympod with inhomonomous spines, the distal one slightly longer than others; exopod of uropod slightly longer than endopod, with three setae, endopod of uropod with two setae and a spine-like structure; anal operculum not protruded. It differs from all the other Hexabathynella species (except H. robeensis) by the presence of an epipod only on thoracopods III and IV. Similarities and differences with other Hexabathynella species are listed in (Appendix 7). The sequenced specimens differ from all the other Hexabathynella species sequenced by COI = 9 – 24.3 % and 12 S = 8.2 – 21.9 %. This species shows mean intraspecific variation of COI = 7 % and 12 S = 3.6 % (Tables 4, 5).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF84FF9053BB05CBFEA3F849.taxon	description	Description male holotype (WAMC 78971): Body elongated, about six times as long as maximum width, almost cylindrical, segments slightly widening towards the posterior end of the body (Appendix 8). Antennula (Fig. 27 A): six-segmented. Length of first three articles about 1.3 times as long as the last three. First article is the longest followed by the sixth one. Fourth article is the shortest, followed by the fifth one. Antennal organ on the second article without protuberance, formed by one modified smooth seta that reaches the distal end of the third article. Inner flagellum almost square. Article five and six with three terminal and three subterminal aesthetascs respectively. Setation as Figure 27 A. Antenna (Fig. 27 B): five-segmented, distal article is the longest, similar in length to the other four combined. Articles one and two with no setae. Articles three and four with one seta each, and article five with two smooth and one plumose setae. Labrum (Fig. 27 C): almost flat, with eleven main teeth. Mandible (Fig. 27 D): pars incisiva with three teeth, pars molaris with five teeth, with the two most proximal ones joined together and covered in fine setules; tooth of ventral edge triangular. Mandibular palp with one distal seta reaching beyond the distal end the pars incisiva. Paragnaths (Fig. 27 E): presence of a rounded structure, with small spines on the distal end, that could represent the support of possible paragnaths, in this case absent. Maxillula (Fig. 27 F): proximal endite with four distal claws of different size, two very long; distal endite with five claws, the three proximal with denticles and all very long, as long setae; three smooth subterminal setae on the outer distal margin. Maxilla (Fig. 27 G): four-segmented, with long setae, setal formula 2, 3, 9, 1. Thoracopods I to VI (Fig. 28 A – G): length gradually increasing from thoracopod one to three, ThIV and VI slightly longer than ThV. Epipod present in ThIII and IV, about one-third of the length of the corresponding basipod. Basipod of ThI and II (Fig. 28 A, B) with one short, smooth, distolateral seta, absent in ThIII to VI (Fig. 28 C – G). Exopod one-segmented and shorter than the first two articles of the endopod, with one barbed seta in ThI; two-segmented in ThII to VI, shorter than the endopod, with the first article similar in in length to the first two articles of the endopod. First and second exopodal article of ThII to VI provided with one barbed seta. Endopod four-segmented, first article short, second and third long and similar in length; fourth segment reduced with two strong claws and one seta on ThI, one smooth long claw and one seta on ThII to IV, and one long claw on ThV to VI; outer seta on second segment of ThI – VI plumose. Setal formula of endopods: ThI 1 + 0 / 0 + 1 / 1 + 0 / 2 + 1 ThII to IV 0 + 0 / 0 + 1 / 0 + 1 / 1 + 1 ThV to VI 0 + 0 / 0 + 1 / 0 + 0 / 1 Thoracopod VIII male (Fig. 27 H, I): compact, almost rectangular. Penial region with massive protopod, frontal lobe trapezoidal, and middle lobe square with several teeth. Endopod as long as basipod, with two small terminal spines. Basipod with one seta and a rounded distal “ crest ” on inner edge. Exopod small, almost square, with two small teeth. Pleopod: absent. Uropod (Fig. 28 H): sympod almost three times the length of the exopod and almost five times as long as wide, with eight inhomonomous spines, with the distal one slightly longer, occupying a little more than half of the sympod length. Exopod slightly longer than endopod, with two terminal barbed setae of different length and a short spine-like seta; distolateral angle of the endopod bearing a short spine-like structure, and two setae, one short and smooth, and one plumose that exceeds the tip of the dagger-shaped distal end of the endopod. Pleotelson (Fig. 28 I): with two smooth lateral setae on each side; anal operculum not protruded. Furca (Fig. 28 I): each ramus almost square, with three barbed, distally bifurcate spines; basal spine shorter. Two dorsal plumose setae, one small and one over twice the length of the distal spine. Female paratype differs from male in the absence of AO on the second antennular segment (Fig. 27 K) and in the thoracopod VIII, which is a small “ bump-like ” structure (Fig. 27 J). Variability: variability was observed in body size (males body length 0.38 – 0.48. mm, and females 0.42 – 0.53 mm), and number of spines on sympod (six to eight, one case (on one side) had five spines).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF84FF9053BB05CBFEA3F849.taxon	distribution	Distribution and remarks: H. julianae sp. nov. was collected from nine bores along the Robe River valley. Sampling is still occurring in the area, and it is possible that the distribution could extend beyond these nine bores (Biologic Environmental Survey unpublished data). This species was previously known by Biologic Environmental Survey as H. sp. PBAT 037. The clade representing this species is not supported in our analyses, however the clade including H. julianae sp. nov., H. sp. 24 (Pardoo) and H. sp. GrPar is supported in both analyses (Fig. 3, Appendix 4). H. julianae sp. nov. has high COI intraspecific variation comprised between 0.2 and 10.2 % (mean 7 %, Table 4, Supplementary Material Table S 3), similar to the COI p-distance between H. julianae sp. nov. and H. sp. 24 (Pardoo) (7 – 10.5 %, mean 9 %). COI p-distance between H. julianae sp. nov. and H. sp. GrPar is slightly higher (10.4 – 14.4 %, mean 12.7 %). Although H. sp. 24 (Pardoo) and H. sp. GrPar occur respectively over 300 km away and over 170 km from H. julianae sp. nov. (Fig. 3), it is possible that they represent populations of the same species complex. H. sp. 24 (Pardoo) morphological analysis was not possible as the posterior half of the body was used for DNA extraction, however a preliminary study showed the presence of epipod only on thoracopods III and IV (Appendix 9). We did not conduct a thorough morphological study of H. sp. GrPar specimens, however, a preliminary analysis showed similarities with H. julianae sp. nov., like the peculiar presence of epipod on thoracopods III and IV only (Appendix 10).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FF84FF9053BB05CBFEA3F849.taxon	etymology	Etymology: the species is dedicated to Juliana Pille-Arnold, one of the collectors of the species and a colleague.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFF8FF9453BB05CBFB9AF93D.taxon	description	(Figs. 29, 30, Appendix 11)	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFF8FF9453BB05CBFB9AF93D.taxon	materials_examined	Material examined: Holotype male. AUSTRALIA: Western Australia: Robe Valley, Pilbara, Bore BC 4341 (stygo net haul) 21 ° 56 ' 57.5344 " S, 116 ° 27 ' 46.7950 " E, 17 March 2022, J. Pille Arnold, S. Rodman, (WAMC 79100 — BES 14051, permanent slide). Paratypes: 1 specimen (sex not available) (WAMC 78949 — BES 17250 — BMR 07033), same details as holotype; 1 female (WAMC 789101 — BES 14051), same details as holotype; 1 male, Robe Valley, Pilbara, Bore BC 401 (stygo net haul) 21 ° 56 ' 10.5876 " S, 116 ° 27 ' 12.5644 " E, 24 May 2021, J. Pille Arnold, S. Rodman, (WAMC 78947 — BES 12997 — BMR 01291, permanent slide); 1 female, Robe Valley, Pilbara, Bore BUNWP 0005 (stygo net haul) 21 ° 55 ' 47.0437 " S, 116 ° 26 ' 06.1447 " E, 17 March 2022, J. Pille Arnold, S. Rodman, (WAMC 78952 — BES 17554 — BMR 07029, permanent slide); 1 male (WAMC 78953 — BES 14471, permanent slide), same details as WAMC 78952; 1 specimen (sex not available), Robe Valley, Pilbara, Bore PZ 10 BUN 041 (stygo net haul) 21 ° 48 ' 53.3830 " S, 116 ° 19 ' 46.2076 " E, 25 September 2021, J. Pille Arnold, S. Rodman, (WAMC 78955 — BES 13433 — BMR 05498, permanent slide); 1 specimen (sex not available), Robe Valley, Pilbara, Bore PZ 10 BUN 043 (stygo net haul) 21 ° 51 ' 18.4911 " S, 116 ° 23 ' 03.3166 " E, 25 September 2021, J. Pille Arnold, S. Rodman, (WAMC 78959 — BES 13555 — BMR 05504, permanent slide); 1 female, Robe Valley, Pilbara, Bore BC 434 (stygo net haul) 21 ° 56 ' 57.5344 " S, 116 ° 27 ' 46.7950 " E, 11 August 2022, J. Pille Arnold, S. Rodman, (WAMC 79012, permanent slide). Additional material: 2 males, 1 female (WAMC 78946 — BES 13080, in alcohol), same details as WAMC 78947; 13 specimens (WAMC 78948 — BES 12437, in alcohol), same details as WAMC 78947; 13 specimens (WAMC 78948 — BES 12437, in alcohol), same details as WAMC 78947; 4 males, 9 females (WAMC 78950 — BES 14051, in alcohol), same details as holotype; 1 female (WAMC 78951 — BES 15661, in alcohol) same details as holotype; 3 males Robe Valley, Pilbara, Bore BUNWP 0005 (stygo net haul) 21 ° 55 ' 47.0437 " S, 116 ° 26 ' 06.1447 " E, 11 August 2022, J. Pille Arnold, S. Rodman (WAMC 78954 — BES 16815, in alcohol); 1 male (WAMC 78956 — BES 13351, in alcohol), same details as WAMC 78955; 1 male, 1 female (WAMC 78957 — BES 15599, in alcohol), same details as WAMC 78955; 1 male (WAMC 78958 — BES 13359, in alcohol), same details as WAMC 78959; 2 males, 1 female, Robe Valley, Pilbara, Bore PZ 10 BUN 043 (stygo net haul) 21 ° 51 ' 18.4911 " S, 116 ° 23 ' 03.3166 " E, 14 August 2022, J. Pille Arnold, S. Rodman, (WAMC 78961 — BES 15925, in alcohol).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFF8FF9453BB05CBFB9AF93D.taxon	diagnosis	Diagnosis: H. robeensis sp. nov. belongs to a group of Hexabathynella with small size (0.36 – 0.51 mm); male antennal organ formed by one modified seta without protuberance; three teeth on pars incisiva and five on pars molaris of mandible; presence of a rounded structure with small spines on the distal end that could represent the support of possible paragnaths, in this case absent; exopod of all thoracopods two-segmented; pleopods absent; sympod of the uropod inhomonomous; exopod and endopod of uropod with three setae, with exopod slightly longer than endopod; anal operculum not protruded. This species is characterized by the presence of epipod on thoracopods III and IV only. H. robeensis sp. nov. is very similar to H. julianae sp. nov. It differs from it by the number of setae on maxilla, the number of spines on the sympod of uropod, the length of setae on exopod and endopod of uropod, and the absence of female thoracopod VIII. Similarities and differences with other Hexabathynella species are listed in Table 10. The sequenced specimens differ from all the other Hexabathynella species sequenced by COI = 11.6 – 22 % and 12 S = 11.3 – 22.2 % This species shows intraspecific variation of COI = 3 % and 12 S = 2.6 % (Tables 4, 5).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFF8FF9453BB05CBFB9AF93D.taxon	description	Description male holotype (WAMC 79100): Body elongated, almost cylindrical, about five and a half times as long as maximum width, segments slightly widening towards the posterior end of the body (Appendix 11). Antennula (Fig. 29 A): first three articles as long as the last three. The first and last articles longest and similar in length, followed by the second article, a little shorter, third and fourth articles similar in length, and fifth one is the shortest. Antennal organ on the second article without protuberance, formed by one smooth modified seta that does not reach the distal end of the third article. Inner flagellum rectangular. Article five and six with three terminal and three subterminal aesthetascs respectively. Setation as Figure 29 A. Antenna (Figure 29 B): five-segmented, distal article longest, about 1.5 times longer than third and fourth ones, which are similar in length, first and second articles shortest, about half of the length of the third one. Articles one, two and four with no setae. Article three with one seta, and article five with two smooth and one plumose seta. Labrum (Fig. 29 C): almost flat, with 12 similar teeth in the distal end. Mandible (Fig. 29 D): pars incisiva with three teeth, pars molaris with five teeth, with the two most proximal ones joined together and covered in fine setules; tooth of ventral edge triangular. Mandibular palp with one distal seta reaching the distal end the pars incisiva. Paragnaths (Fig. 29 E): presence of a rounded structure, with small spinnule on the distal end, that could represent the support of possible paragnaths, in this case absent. Maxillula (Fig. 29 F): proximal endite with four distal claws of different size, one very long and two short ones similar in length; distal endite with five claws, the three proximal ones with denticles, and the basal one short; three smooth subterminal setae on the outer distal margin. Maxilla (Fig. 29 G): four-segmented, with long setae, setal formula 2, 4, 13, 1. Thoracopods I to VI (Fig. 30 A – F): ThII slightly longer than ThI, ThIII to VI longer than ThII and similar in size. Epipod present on ThIII and IV only, small, about one-third of the length of the corresponding basipod. Basipod of thoracopods I and II with distolateral seta, basipod of ThIII to VI without. Exopod one-segmented and shorter than the first two articles of the endopod in ThI, with only one distal seta; exopod two-segmented and shorter than the first three segments of the endopod in ThII to VI, with two barbed setae, one terminal and one subterminal. Endopod four-segmented, first article short, second and third long and similar in length; fourth segment reduced with two smooth claws and one seta on ThI, one smooth claw and one seta on thoracopods II to IV, and one claw on ThV and VI; outer seta on second segment of ThI – VI plumose. Setal formula of endopods: ThI 1 + 0 / 0 + 1 / 1 + 0 / 2 + 1 ThII to IV 0 + 0 / 0 + 1 / 0 + 0 / 1 + 1 ThV to VI 0 + 0 / 0 + 1 / 0 + 0 / 1 Thoracopod VIII male (Fig. 29 H, I): compact, rectangular. Penial region with massive protopod, frontal lobe rectangular, and middle lobe nearly square. Endopod short, with one strong terminal seta. Basipod slightly longer than endopod, without seta and with a lobed distal “ crest ” on inner edge. Small subtriangular exopod without teeth. Pleopod: absent. Uropod (Fig. 30 G): sympod almost 2.5 times the length of the exopod and over six times as long as wide, with five inhomonomous spines occupying 2 / 3 of its length, with distal spine longer. Exopod slightly longer than endopod, with one short subterminal barbed seta, and two terminal setae, one barbed and one long and smooth; distolateral angle of the endopod bearing one plumose seta, and two smooth short setae not reaching the end of the dagger-shaped structure of the endopod. Pleotelson (Fig. 30 H): with two plumose lateral setae on each side; anal operculum not protruded. Furca (Fig. 30 H): each ramus rectangular, with three barbed spines; basal spine shortest, other two similar in length. Two dorsal plumose setae, one short and one slightly longer than the distal spine. Female paratype differs from male in the second antennular segment without AO (Fig. 29 J), and the absence of thoracopod VIII. Variability: variability was observed in body size (males 0.36 – 0.5 mm and females 0.37 – 0.47 mm), and number of inhomonomous spines on sympod (four to six). In some cases, left and right exopods of thoracopods are different, with one side presenting one-segmented exopod.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFF8FF9453BB05CBFB9AF93D.taxon	distribution	Distribution and remarks: H. robeensis sp. nov. was collected in five bores in the Robe River valley and its distribution overlaps with H. julianae sp. nov. one (Fig. 3). Sampling is still occurring in the area, and the distribution could extend beyond these nine bores (Biologic Environmental Survey unpublished data). This species was previously known by Biologic Environmental Survey as H. sp. PBAT 033 / PBAT 047 / Helix-SPA 051. The clade representing this species is well supported and is sister to the clade formed by H. julianae sp. nov., H. sp. GrPar and H. sp. 24 (Pardoo), with COI p-distances comprised between 11.6 and 14.7 % (Table 4).	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
0399C326FFF8FF9453BB05CBFB9AF93D.taxon	etymology	Etymology: the name of the species refers to the Robe Valley where it occurs.	en	Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Lawrie, Angus, Floeckner, Stephanie, Guzik, Michelle T. (2025): New species of Atopobathynella, Kimberleybathynella and Hexabathynella (Parabathynellidae, Bathynellacea) from the arid zones of Western Australia. Zootaxa 5655 (1): 1-103, DOI: 10.11646/zootaxa.5655.1.1, URL: https://doi.org/10.11646/zootaxa.5655.1.1
