BATHYNELLIDAE Grobben, 1905

Camacho, A. I., Hutchins, B., Schwartz, B. F., Dorda, B. A., Casado, A. & Rey, I., 2017, Description of a new genus and species of Bathynellidae (Crustacea: Bathynellacea) from Texas based on morphological and molecular characters, Journal of Natural History 52 (1 - 2), pp. 29-51 : 35-38

Family BATHYNELLIDAE Grobben, 1905

Bathynellidae currently consist of three subfamilies: Bathynellinae Grobben, 1905 , Gallobathynellinae Serban et al., Coineau and Delamare Deboutteville, 1971 and Austrobathynellinae Delamare Deboutteville & Serban, 1973 ( Table 2). The two genera adequately described from the USA, Bathynella Vejdovsky, 1882 and Paci fi cabathynella Schminke and Noodt, 1988, belong to Bathynellinae .

The diagnosis of the Gallobathynellinae should be slightly amended to include the new genus as we will justify later, after the complete description of the new species.

Subfamily GALLOBATHYNELLINAE Serban, Coineau and Delamare Deboutteville,1971

Amended diagnosis

(After Serban, Coineau and Delamare Debouteville, 1971 and Serban, 1989a, 1989b).

Antennule 6- or 7-segmented. Antenna endopod 3- or 5-segmented. Apical part of paragnaths with thin setae. Prehensile mandibular palp unsegmented or 3-segmented, both sexes with similar or different claws on the terminal segment; pars incisiva (incisor process) (‘ pars incisive ’) of mandible with two simple teeth and processus incisivus accesorius (molar process); pars molaris of mandible normally made up of two parts, more or less complex, with simple or denticulate teeth. Endopod 3-segmented on thoracopods II, IV, V and VI, or 4-segmented in all pairs; male thoracopod VII without coxal endite. Penial region (‘ región pénienne ’) of male thoracopod VIII with one lobe and an apically developed frontal projection (Fr.prj) (‘ prolongement rostral ’), or with one lobe, one frontal projection and one large outer lobe (O.lb) (‘ lobe externe ’); basipod welldeveloped vertical or inclined generally with an outer protuberance (O.pr) (‘ proéminence externe ’); exopod similar to the rest of thoracopods, always present; endopod small, un-segmented, or absent. Female thoracopod VIII variable, similar to Bathynellinae (with length of rami similar or not) or uniramous and reduced to only two segments (coxopod and basipod); exopod with two terminal setae, sometimes exceptionally shorter than endopod; coxal seta elongated or reduced. Sympod of uropod with three to five spines (‘ épines ’); endopod with two or four claws (‘ griffes ’). Furcal rami with second spine, in almost all cases, longer than the other four.

This subfamily currently includes 11 genera, and 25 species, all in Europe: Iberian Peninsula ( Portugal and Spain), France, Italy, Switzerland and Germany (Camacho et al. 2017).

Hobbsinella gen. nov. Camacho, Hutchins, Schwartz, Dorda, Casado and Rey.

Genus diagnosis ( Table 3)

Antennule and antenna seven-segmented. Antenna much longer than antennule. Mandibular palp sexually dimorphic. Endopod of thoracopods I – VII each four-segmented. Male thoracopod VIII of globular aspect; penial region with two small lobes, inner lobe, and a frontal projection, and with a group of small denticles at base; basipod large, vertical, with frontal crest provided with teeth and lateral rim of spines and one distal seta and a large outer protuberance completely integrated on coxopod; exopod very elongated, as long as preceding thoracopods, with five setae; endopod with two setae of different size. Female thoracopod VIII with a reduced ‘ seta ’ on coxopod; epipod very large; exopod longer than endopod. Uropod: sympod with five spines; endopod with four spines. Furcal rami with second spine a little longer than rest, which are all equal in length.

Type species: Hobbsinella edwardensis sp. nov.

Hobbsinella edwardensis gen. et sp. nov., Camacho, Hutchins, Schwartz, Dorda, Casado and Rey

( Figures 2 – 6 )

Material examined ( Table 4)

Type locality. San Marcos artesian well, Hays County, Texas USA ( WGS84 29.8896°, −97.9364°, 177 m amsl): holotype male ( MNCN 20.04 /17820) (coll. 23 June 2015, together with two juveniles, B. Hutchins and B. Schwartz) .

Paratypes (coll by B. Hutchins, B. Schwartz): 1 ♂ (10 March, 2013), 1 ♀ (20 March, 2013), 1 ♂ + 3 ♀ (16 June, 2015), 2 ♂ (19 June, 2015), 1 ♂ + 1 ♀ (23 June, 2015). Additional material examined. Panther Canyon well, Comal County, Texas USA ( WGS84 29.7136°, −98.13841°, 207 m amsl): 1 ♂ (coll. 25 February 2010, R. Gibson and P. Diaz); Finegan Springs, Val Verde County, Texas USA ( WGS84 29.9011°, −100.9987°, 406 m amsl): 1♂ (coll. 25 October 2014, R. Gibson) .

All 16 specimens collected (five females, eight males, two juveniles and one damaged specimen) belong to the type series: 13 slides (morphological type series MNCN 20.04 / 17812 to MNCN 20.04 /17824), together with eight DNA extractions from the specimens used for molecular analysis, DNA types ( MNCN /ADN 29943, MNCN /ADN 29944, MNCN / ADN 54637 to 54640 , MNCN /ADN 54644 and MNCN /ADN 54646) (see Table 4) . Details of the descriptions are based on all adult specimens of the type series. All drawings correspond to the holotype (male) except for Th VIII female, and one Md figure that belongs to a female of the type series ( Figure 3 (g)).

Description

Body ( Figure 2 ). Total length of holotype 1.42 mm. Total length of males 1.3 – 1.4 mm, of females 1.3 – 1.6 mm. Body elongated, segments widening slightly towards posterior end, approximately 10 times as long as wide. Head longer than wide. Pleotelson with one small barbed dorsal seta at each side.

Antennule ( Figure 3 (a)). Seven-segmented; first three segments almost as long as last four segments combined; first segment as long as last segment, which is more slender than rest of segments; fourth and fifth segments shortest and equal in length; inner flagellum almost square, reduced; setation as in Figure 3 (a); segment three with five smooth setae; segment six with two aesthetascs, similar in size; seventh segment with three aesthetascs, each of a different size and shorter than those of segment six. A I shorter than antenna.

Antenna ( Figure 3 (b)). Seven-segmented; 33% longer than A.I; first segment long; second and third shortest; fourth and seventh similar in length, very elongate; fifth and sixth similar, measuring just over half length of distal segment; setal formula: 0 + 0/ 1 + 0/2 + 0/2 + 0/0 + 0/2 + 2/5.

Figures

Figure 2. Habitus of Hobbsinella edwardensis gen. et sp. nov.

Figure 3. Hobbsinella edwardensis gen. et sp. nov. (a–f, h, i) Male holotype. (a) Antennule; (b) antenna; (c) labrum; (d) paragnath; (e) mandible; (f) masticatory part of mandible; (g) female mandible; (h) maxillule; (i) maxilla. Scale bar in mm.

Figure 4. Hobbsinella edwardensis gen. et sp. nov., male holotype. (a) Thoracopod I; (b) thoracopod II; (c) thoracopod III; (d) thoracopod IV. Scale bar in mm.

Figure 5. Hobbsinella edwardensis gen. et sp. nov., male holotype. (a) Thoracopod V; (b) thoracopod VI; (c) thoracopod VII. Scale bar in mm.

Figure 6. Hobbsinella edwardensis gen. et sp. nov. (a–d, f–i) male holotype. (a) thoracopod VIII (latero-internal view); (b) thoracopod VIII (latero-internal view); (c) thoracopod VIII (latero-external view); (d) thoracopod VIII (latero-external view); (e) female thoracopod VIII; (f) pleopod (frontal view); (g) uropod (dorsal view); (h) furcal ramus (dorsal view); (i) distal end of endopod of uropod (dorsal view). Scale bar in mm. Abbreviations: Fr. prj., frontal projection; O. prt., outer protuberance; I. Lb, inner lobe; Crt.bsp, crest of basipod; Bsp, basipod; Endp, endopod; Exp, exopod; D. sp., dorsal spine.