Kimberleybathynella ordensis Perina & Camacho, 2025

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), pp. 1-103 : 53-56

Kimberleybathynella ordensis Perina & Camacho urn:lsid:zoobank.org:act:CF5535BF-DC64-46FD-B54E-F91CE2AFA2C7

( Figs. 21 & 22 )

Material examined. Holotype male. AUSTRALIA: Western Australia: Ord River, Kimberley, Bore T4 GRC225 (pump sample), 17°35'45.7525"S, 127°55'43.4766"E, 28 April 2017, S. Callan, M. O’Connell ( WAMC 79094 — BES2156 b— BMR8555 , permanent slide).

Paratypes: AUSTRALIA: Western Australia: 1 female, ( WAMC 79095 — BES2156 b, in alcohol), same details as holotype ; 1 female, Ord River, Kimberley, Bore T6 GRC210 (pump sample), 17°36'34.3106"S, 127°57'46.6114"E, 27 April 2017, S. Callan, M. O’Connell ( WAM C79096 — BES2132 b— BMR8556 permanent slide) ; 1 female, Ord River, Kimberley, Bore T4 GRC216east (pump sample), 17°35'47.3238"S, 127°55'39.0822"E, 25 April 2017, S. Callan, M. O’Connell ( WAMC 79092 — BES1956 b— BMR08554 , permanent slide) ; 1 male, Ord River, Kimberley, Bore T4 GRC240 (pump sample), 17°36'19.8003"S, 127°54'55.1952"E, 25 April 2017, S. Callan, M. O’Connell ( WAMC 79097 — BES2194 b— BMR8558 , permanent slide) ; 1 female ( WAMC 79098 — BES2194 b— BMR8559 , permanent slide), same details as above ; 1 male ( WAMC 79009 — BES2194 b, permanent slide), same details as above ; 1 female ( WAMC 790010 — BES2194 b, permanent slide), same details as above ; 1 specimen (sex not available) ( WAMC 790011 — BES2194 b, permanent slide), same details as above .

Additional material AUSTRALIA: Western Australia: 1 female, Ord River, Kimberley, Bore T4 GRC216east (pump sample), 17°35'47.3238"S, 127°55'39.0822"E, 25 April 2017, S. Callan, M. O’Connell ( WAMC 79093 — BES1956 b, in alcohol) ; 3 males, 3 females, Ord River, Kimberley, Bore T4 GRC240 (pump sample), 17°36'19.8003"S, 127°54'55.1952"E, 25 April 2017, S. Callan, M. O’Connell ( WAMC 79099 — BES2194 b, in alcohol) .

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 12S = 17.6% (S.E. = 0.4%) with K. callani sp. nov..

Description male holotype (WAM C79094). 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. 21A ): 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. 21A .

Antenna ( Fig. 1B ): 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. 21C ): 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. 21D, 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. 21E ): 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. 21F ): four-segmented, first and second articles partially fused, setal formula 2, 4, 15, 1.

Thoracopods I to VII ( Figs. 22A–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. 22H ): one seta on each side.

Uropod ( Fig. 22I ): 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. 22J ): 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. 21J ), 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).

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.

Etymology. The name of the species is derived from the Ord River, which is close to the type locality.

Figures

FIGURE 1. Atopobathynella species distribution in the Pilbara (WA).

FIGURE 2. Kimberleybathynella species distribution in the Kimberley (WA).

FIGURE 21. Kimberleybathynella ordensis sp. nov. Male holotype (WAM C79094) unless specified. A, Antennula (dorsal view; B, Antenna dorsal view; C, Labrum; D, Mandible (male paratype WAMC 79097); E, Maxillula; F, Maxilla (dorsal view); G, Mandible female paratype (WAMC 79096); H, Thoracopod VIII (latero-internal view); I, Thoracopod VIII (latero-external view); J, Female Thoracopod VIII (WAM C79096). (O.Lb) outer lobe, (Bsp) basipod, (Exp) exopod, (Endp) endopod. Scale bar in mm.

FIGURE 22. Kimberleybathynella ordensis sp. nov. Male holotype (WAM C79094) unless specified. A, Thoracopod I; B, Thoracopod II; C, Thoracopod III; D, Thoracopod IV; E, Thoracopod V; F, Thoracopod VI; G, Thoracopod VII; H, Pleopods I to V female paratype (WAMC 79095); I, Uropod (latero-external view); J, Furcal rami (dorsal view). Scale bar in mm.