Diacyclops ballaballaensis, Karanovic, 2024

Karanovic, Tomislav, 2024, Six new species of Diacyclops (Copepoda: Cyclopoida) from Australia, Zootaxa 5541 (2), pp. 101-143 : 116-121

publication ID	https://doi.org/ 10.11646/zootaxa.5541.2.1
publication LSID	lsid:zoobank.org:pub:86A7CD79-F5A2-4AA6-A6AA-01C0CB64B29C
persistent identifier	https://treatment.plazi.org/id/03E8C55F-9C05-FFC2-FF0B-9372FA6F6284
treatment provided by	Plazi
scientific name	Diacyclops ballaballaensis
status	sp. nov.

Treatment

Diacyclops ballaballaensis sp. nov.

( Figs. 1C View FIGURE 1 , 13–16 View FIGURE 13 View FIGURE 14 View FIGURE 15 View FIGURE 16 )

urn:lsid:zoobank.org:act:22E70096-E81F-4238-9576-FC7E40509A05

Type locality. Western Australia, Pilbara Region, Balla Balla Station , bore BBR052, sample no. FBN111, 20.764256°S 117.750643°E, 5 August 2008, collected by E. Thomas. GoogleMaps

Holotype. Adult female dissected on 1 microscope slide.

Paratypes. One female from type locality dissected on 1 microscope slide; 1 female and 1 copepod from type locality in 1 alcohol vial; 1 male dissected on 1 microscope slide from bore BBWP015 , Balla Balla Station, Pilbara Region , Western Australia, 20.805288°S 117.758197°E, sample no. FBN102, 8 June 2008, collected by E. Thomas GoogleMaps ; 1 male and 1 female from bore BBWP015 (see above) and 1 female from Harding Dam, Pilbara Region , Western Australia, 20.970278°S 117.090278°E, sample no. HD3/00, 3 April 2003, collected by J. Cocking and M. Scanlon GoogleMaps , together on 1 SEM stub (row no. 1), together with 5 other species described here; 1 copepodid from bore BBMB007 , Balla Balla Station, Pilbara Region , Western Australia, 20.749846°S 117.778707°E, sample no. FBN012, 4 December 2007, collected by E. Thomas GoogleMaps , in 1 alcohol vial.

Etymology. The species name refers to its type locality, Balla Balla Station, which is a pastoral lease and cattle station about 140 km east of Karratha in Western Australia. It is an adjective for place, made with the Latin suffix “ -ensis ”.

Diagnosis. Female. Body length from 520 to 540 µm. Habitus ( Fig. 1C View FIGURE 1 ) robust, 2.75 times as long as wide, with prosome/urosome ratio of more than 1.6, and cephalothorax nearly 2.5 times as wide as genital double-somite in dorsal view. Integument on all somites ( Fig. 16A, B View FIGURE 16 ) thin and wrinkled, with light bacterial cover; general distribution of spinules and cuticular pores on somites as in D. leijsi . Hyaline fringes of prosomites ( Fig. 16A View FIGURE 16 ) and first urosomite ( Fig. 16A View FIGURE 16 ) smooth, those of genital double-somite and 2 subsequent urosomites ( Figs. 13A View FIGURE 13 , 16B View FIGURE 16 ) very slightly wavy. Genital double-somite ( Figs. 13A View FIGURE 13 , 16A View FIGURE 16 ) wider than long in ventral view, widest at first third of its length and gradually tapering posteriorly, widest part about 1.5 times as wide as posterior margin; seminal receptacle smaller than in previous 2 species, anterior part less dome-like, posterior part short and broad; copulatory pore small and located more posteriorly than in previous 2 species; copulatory duct wide, long, and well-sclerotized. Anal somite ( Figs. 13A View FIGURE 13 , 16B View FIGURE 16 ) more cleft than in previous 2 species, with minute spinules along ventral margin. Caudal rami ( Figs. 13A View FIGURE 13 , 16B View FIGURE 16 ) long and slender, widely spaced, nearly 4.6 times as long as wide and about 2.7 times as long as anal somite; principal terminal setae without breaking planes, inner one strong and slightly longer than entire urosome, outer one greatly reduced and even shorter than innermost terminal seta; dorsal seta extremely long, about 3 times as long as caudal ramus, nearly 10 times as long as innermost terminal seta, and about 9 times as long as outermost terminal seta. Antennula ( Fig. 13B View FIGURE 13 ) 12-segmented, slightly shorter than cephalothorax, with single aesthetasc on fifth segment and setae formula 8.4.2.6.3.2.2.3.2.2.2.8; ultimate segment about 1.9 times as long as wide. Antenna ( Fig. 13C View FIGURE 13 ) 5-segmented, without exopodal seta, with setae formula 0.2.1.5.7; second segment about 1.4 times as long as fifth segment. Labrum ( Fig. 13D View FIGURE 13 ) with 2 diagonal rows of 12–13 slender spinules each on anterior surface, and short rows of minute spinules in blunt lateral corners; cutting edge nearly straight, with 16 sharp teeth. Mandibula ( Fig. 13E View FIGURE 13 ) similar to that in D. leijsi , but with 1 less unicuspidate tooth on cutting edge. Maxillula ( Fig. 13F View FIGURE 13 ) also similar to that in D. leijsi , but without exopodal seta on its palp. Maxilla ( Fig. 13G View FIGURE 13 ) similar to that in D. leijsi , but basal spine less robust and partly articulated basally. Maxilliped slenderer than in previous 2 species, with setae formula 1.2.1.2. Shape and segmentation of all swimming legs ( Fig. 14A, B, C, E View FIGURE 14 ) as in D. leijsi , but second and third endopodal segment of first to third leg partly fused towards inner margin, while endopod of fourth leg clearly 3-segmented; basis of first leg with long outer seta and short inner spine, latter slightly shorter that first endopodal segment; basis of second to fourth legs with shorter outer seta and inner distal corner blunt; all first exopodal segments without inner seta; all second exopodal segments, all first endopodal segments, and second endopodal segment of first to third legs with single inner seta; second endopodal segment of fourth leg with 2 inner setae; third exopodal segments spine formula 2.3.3.3 and setae formula 4.4.4.4; third endopodal segments of first to third leg with 2 inner setae, 1 apical seta, 1 apical spine, and 1 outer seta; third endopodal segment of fourth leg about 1.7 times as long as wide, with 2 inner setae, 1 apical spine, and 1 outer seta; its apical spine slightly longer than segment. Fifth leg ( Figs. 13A View FIGURE 13 , 14F View FIGURE 14 ) shape and segmentation as in D. leijsi ; second segment about 1.7 times as long as wide and only half as long as its spine. Sixth leg ( Figs. 14G View FIGURE 14 , 16A View FIGURE 16 ) minute, with very short outer seta.

Male. Body length from 515 to 530 µm. Habitus and urosome ( Fig. 15A View FIGURE 15 ) slightly slenderer than in female; free genital somite ( Fig.15A View FIGURE 15 ) about 1.5 times as wide as subsequent urosomite, with relatively large ovoid spermatophores. Ornamentation of cephalothorax, free prosomites, and last 3 urosomites ( Fig. 15A View FIGURE 15 ) as in female. Caudal rami ( Fig. 15A View FIGURE 15 ) significantly shorter than in female, only about 3.5 times as long as wide in ventral view; dorsal seta also considerably shorter in female, only about 1.9 times as long as ramus; reduced outer principal terminal seta longer than in female, about 1.9 times about as long as innermost terminal seta. Antennula ( Figs. 15B, C View FIGURE 15 , 16C, D View FIGURE 16 ) very similar to that in D. leijsi , but shorter, fifth segment reduced in size, and ninth segment almost completely fused with eighth; armature and ornamentation of first 4 and last 7 segments as in D. leijsi , except ultimate segment missing smallest seta in distal cluster; fifth segment unarmed (two setae missing), ninth segment missing one seta, and seta on eighth segment smaller when compared to D. leijsi ; penultimate segment about 1.7 times as long as wide. Antenna ( Fig. 16C, E View FIGURE 16 ), labrum ( Fig. 16E View FIGURE 16 ), mandibula ( Fig. 16E View FIGURE 16 ), maxillula ( Fig. 16E View FIGURE 16 ), maxilla ( Fig. 16E View FIGURE 16 ), and maxilliped as in female. All swimming legs ( Figs. 15D, E, F, G, H View FIGURE 15 , 16F View FIGURE 16 ) with completely divided second and third endopodal segments, but armature and ornamentation as in female; third exopodal segments of first ( Fig. 15E View FIGURE 15 ) to fourth ( Fig. 15G View FIGURE 15 ) legs, as well as third endopodal segment of fourth leg ( Fig. 15H View FIGURE 15 ), shorter than in female. Fifth leg as in female. Sixth leg ( Fig. 15A View FIGURE 15 ) with single short spine.

Variability. One third swimming leg of the holotype female showed an aberrant third exopodal segment ( Fig. 14D View FIGURE 14 ), with 5 spines. The other third leg was normal, with three spines, as in the second swimming leg ( Fig. 14B View FIGURE 14 ).