Atopobathynella abelloana 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 : 26-30

Atopobathynella abelloana Perina & Camacho , sp. nov.

urn:lsid:zoobank.org:act:AF0DA0F4-F621-4D06-BBA8-B282AD77FB99

( Figs. 6–7 )

Material examined. Holotype male. AUSTRALIA: Western Australia: Brockman Pilbara, karaman BS1_ Kara 02, 22°34'29.6998"S, 117°11'23.8466"E, 20 February 2021, P. Runham, S. Floeckner ( WAMC 78930 — BES10765 e— BMR02603 , permanent slide).

Paratypes AUSTRALIA: Western Australia: 1 female, Brockman, Pilbara, Boolgeeda Creek , karaman BS4- KC01, 22°34'32.1312"S, 117° 11'23.7006"E, 17 April 2019, S. Callan, M. Lythe ( WAM C78920 — BES6041 permanent slide) ; 1 female, 1 male ( WAM C78921 — BES6041 permanent slide), same details as above ; 1 female ( WAM C78923 — BES6814 — BMR00622 , permanent slide), same details as above ; 1 female ( WAM C78924 , BES5905 , permanent slide) same details as above ; 1 male ( WAM C78925 — BES5905 , permanent slide) same details as above ; 1 female ( WAM C78926 — BES5905 , permanent slide) same details as above ; 1 female ( WAM C78924 — BES5905 , permanent slide) same details as above ; 1 male ( WAM C78928 v— BES10765 c— BMR02601 permanent slide) same details as holotype ; 1 male ( WAM C78929 — BES10765 d— BMR02602 permanent slide) same details as holotype .

Additional material AUSTRALIA: Western Australia: 1 male, Brockman, Pilbara , karaman BS1-KC02, 22°34'29.6998"S, 117°11'23.8466"E, 20 February 2021, P. Runham, S. Floeckner ( WAMC 78931 — BES10765 f, in alcohol) ; 1 specimen (sex not available), Brockman, Pilbara, Boolgeeda Creek , karaman BS4-KC01, 22°34' 32.1312"S, 117°11'23.7006"E, 17 April 2019, S. Callan, M. Lythe ( WAM C82065 — BES5503 — BMR00673 , in alcohol) ; 1 male ( WAM C78922 — BES6041 , in alcohol), same details above ; 1 female, 1 male, 1 juvenile ( WAM C78927 — BES5905 , in alcohol), same details as above .

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 12S = 11.6–33.6% (Appendices 3, 4).

Description male holotype (WAM C78930). 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. 6A ): 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. 6A .

Antenna ( Fig. 6C ): one-segmented; very short and rectangular with three smooth setae, two terminal and one subterminal.

Labrum ( Fig. 6D ): slightly convex, free edge with 18 teeth, eight on each side and two centrals with distal end denticulated.

Paragnaths ( Fig. 6H ): rudimental structure that could represent paragnaths.

Mandible ( Fig. 6E ): 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. 6F ): 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. 6G ): four-segmented, setal formula 2, 3, 16, 1.

Thoracopods I to VII ( Figs. 7A–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. 6J ): 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. 7H ): long plumose seta on each side, located on the anterior third of the first segment of the pleon.

Uropod ( Fig. 7I ): 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. 7J ): with one small lateral plumose seta on each side; anal operculum not protruded.

Furca ( Fig. 7J ): 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. 6B ) that bears no antennal organ, and in the small pointed thoracopod VIII ( Fig. 6I ).

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).

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-PBAT013”. 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. PBAT032, A. sp. 20 (EM 2019) and A. sp. H SPA050 occurring in the Onslow River Catchment ( Figs. 1 , 5 clade 7).

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.

Figures

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

FIGURE 5. ML tree built using the three-genes alignment (COI-12S-18S). Some nodes collapsed for clarity. Supported nodes in green. New species described in red, new putative species in green. *: hyporheic taxa. Blue rectangles: clades supported in the three-genes and two-genes analyses. Orange rectangles: clades supported only in the three-genes analysis.

FIGURE 6. Atopobathynella abelloana sp. nov. male holotype (WAMC 78930) unless specified. A, AI; B, AI second article (female paratype WAMC 78924); C, AII; D, Lb; E, Md; F, MxI; G, MxII; H, possible paragnaths (male paratype WAMC 78921); I, female ThVIII (latero-internal view) (female paratype WAMC 78924); J, male ThVIII (latero-external view). (O.Lb) outer lobe, (Bsp) basipod, (D. Lb) dentate lobe, (I. Lb) inner lobe). Scale bar: 0.05 mm.

FIGURE 7. Atopobathynella abelloana sp. nov. male holotype (WAMC 78930).A, ThI; B, ThII; C, ThIII; D, ThIV; E, ThV; F, ThVI; G, ThVII; H, pleopod; I, uropod; J, furcal rami. Scale bar: 0.05 mm.