Nicolenella nguyenae Perina & Camacho, sp. nov. (Figs. 17, 18, Appendix 7F) urn:lsid:zoobank.org:act: A6F05771-CBAA-4517-9420-85082F7E7B39 Material examined. Holotype male. AUSTRALIA: Western Australia: Boolgeeda Creek, Pilbara, bore PZ06BS4B007 (stygo net haul), 22°33'55.9177"S, 117°15'30.6612"E, 26 June 2019, M. Lythe, K. Nguyen (WAMC 78901 - BES6457-BMR00621, permanent slide). Paratypes AUSTRALIA: Western Australia: 1 female, bore PZ06BS4B006 (stygo net haul), 22°33'58.4763"S, 117°13'28.3894"E, 20 February 2021, P. Runham, S. Floeckner (WAMC 79086 -BES10698a-BMR02461, permanent slide), 1 male, (WAMC 79087 -BES10698c-BMR02463, permanent slide); 1 male and 1 female (WAMC 79088 - BES7230, in ethanol), same details as holotype; 1 female, (WAMC 78902 -BES7230, permanent slide) same details as holotype. Diagnosis. AI seven-segmented.Antennula 2.5 times longer than antenna.AII six-segmented with the last article very long. Mandibular palp one-segmented formed by one long article and one seta that extends beyond the distal end of the pars incisiva. Distal endite of maxillula with six claws. Two to five articles on exopod of thoracopods. Male thoracopod VIII rectangular, very elongated, two times as long as wide. Sympod of the uropod 2.5 times the length of the exopod and endopod which are similar in length, with homonomous spines; exopod of the uropod with three distal setae and dorsal basal setae. Furca with long spines, the two distal ones slightly longer than the rest. It differs from all other species of Nicolenella gen. nov. by the combination of characters listed in Supplementary Material Table S2. The sequenced specimens differ from all the other Nicolenella gen. nov., Billibathynella and Brevisomabathynella species sequenced by COI = 14.7–23.6% and 12S = 17.2–37% (Table 3, Appendix 2, 3). Description male holotype (WAMC 78901). Body length of 1.38 mm. Body nearly six times as long as maximum width elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of body (Appendix 7F). The description of ThIII to VII is based on female paratype WAMC 78902, because holotype’s legs were subsampled for DNA. We chose WAMC 78901 as holotype, since it is bigger than other males and ThVIII is clearer. Antennula (Fig. 17A): seven-segmented, almost three times longer than AII. The first three articles are similar in length to the last four together. The first article is the longest, followed by the third and sixth, which are similar in length, and slightly longer than the second one, which is longer than the fourth and seventh which are similar in length, fifth article is the smallest. Inner flagellum small and rectangular. The last two articles with three terminal aesthetascs and the fifth with only two. Antennular setation as in Fig. 17A. Antenna (Fig. 17B): six-segmented, the first four articles are as long as the last two together; the first three articles are very small and the sixth is the longest. Setal formula of AII: 0+0/0+0/1+1/1+1/0+0/4. Labrum (Fig. 17C): flat, free edge with 17 teeth. Paragnaths: absent. Mandible (Fig. 17D): pars incisiva with four teeth; pars molaris with seven claws, the five distal ones denticulated, and the two most proximal ones joined together; tooth of ventral edge triangular. Mandibular palp with one long article and one seta exceeding the distal end of the pars incisiva. Maxillula (Fig. 17E): proximal endite with four unequal claws; distal endite with six claws: two apical smooth and four denticulated; three smooth, unequal subterminal setae on the outer distal margin. Maxilla (Fig. 17F): four-segmented, setal formula 3, 4,14,2. Thoracopods I to VII (Figs. 18A–I): length slightly increasing from thoracopod one to seven. Epipod present in thoracopod I to IV, about half of the length of the corresponding basipod. All basipods with one distolateral seta shorter than the first article of the endopod in all thoracopods. Exopod of ThI almost as long as the three first endopodal articles, similar to the length of the endopod in ThII to VI, shorter in ThVII. Exopod of all thoracopod with two distal setae on each article except the first article of ThI that have three setae. Number of exopodal segments of thoracopods I–VII: 3-4-5-5-5-5-4. Endopod four-segmented, first article shorter than second and third articles, second and third articles similar in length, and fourth article very short in all thoracopods; first and second articles bearing an outer plumose seta in all thoracopods, two inner smooth setae on second and third articles on ThI, and one inner smooth seta on the second article in ThII to VII; third article with one short outer distal seta in ThI to VII, and one inner seta on ThI; fourth article with two strong claws of different length and one smooth seta on all thoracopods. Setal formula of endopods as follow: ThI 2+1/2+1/1+1/3(1) ThII to VII 0+1/1+1/0+1/3(1) Thoracopod VIII (Fig. 17 G-J): rectangular, very elongated, two times longer than wide; penial region with massive protopod; outer lobe long, finger-like, without basal delimitation, reaching the distal end of basipod. Dentate lobe with several distal teeth. Inner lobe as long as outer lobe. Basipod without setae and with an anterior projection (or crest). Small, exopod with tooth, and small endopod with two distal setae similar in length. Pleopod I (Fig. 18J): one segmented with a long plumose seta. Uropod (Fig.18K): sympod nearly three times longer than endopod and exopod (which are similar in length), and about five times as long as wide, with a row of seven homonomous spines, occupying about half of its length. Endopod with two strong distal and three small inner spines, two dorsal plumose setae, one of which exceeds the tip of the distal spines, two long distal barbed setae. Exopod with six barbed setae, three long terminal ones, two short dorsal ones, and one short basiventral seta. Pleotelson (Fig. 18L): anal operculum slightly protruded. Furca (Fig. 18L): trapezoidal rami, with 11 barbed spines; the nine proximal one thin, and slightly shorter than the two distal ones, which are thicker. Two dorsal plumose setae, the inner one short and the outer one reaches the tip of the distal spines. Female differs from male in the small cone shaped ThVIII (Fig. 17K). Variability: variability was observed in body size (males 1.13–1.38 mm and females 1.43–1.85 mm); number of teeth of labrum (14–18); number of exopodal articles on the thoracopods (3–5); number of spines on sympod of uropod (7–9) and number of spines on furcal rami (8–11). Distribution and remarks. N. nguyenae sp. nov. has been collected in two bores near Boolegeeda creek (Ashburton River) (Fig. 6, 9B). This species was previously known by Biologic Environmental Surveys as Parabathynellidae sp. “Biologic-PBAT022”. N. nguyenae sp. nov. can be distinguished by the combination of characters listed in Supplementary Material Table S2. It is part of a partially supported clade (Fig. 2) formed by one species collected in the Onslow River Catchment, and four species collected geographically close in the Ashburton River Catchment (N. vanweesae sp. nov., N. hueyi sp. nov., N. mittrai sp. nov., N. rodmani sp. nov.) (Figs. 6, 9B). Etymology. The name of the species is dedicated to a colleague, Kim Nguyen, one of the collectors of this species.

Published as part of Perina, Giulia, Camacho, Ana I., Morgan, Liesel, Floeckner, Stephanie & Guzik, Michelle T., 2025, Morphological and molecular description of ten new species of a new genus of Parabathynellidae (Bathynellacea, Crustacea) from the Pilbara region, Western Australia, pp. 1-103 in Zootaxa 5712 (1) on pages 54-58, DOI: 10.11646/zootaxa.5712.1.1, http://zenodo.org/record/17884411