Nicolenella, Perina & Camacho & Morgan & Floeckner & Guzik, 2025

Nicolenella gen. nov. Perina and Camacho, 2025

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Diagnosis: Body elongated with segments widening towards the posterior end. Antennula seven-segmented. Antenna five, six, or seven-segmented. Labrum flat. Incisor process of mandible with four or five teeth, molar process with five to nine claws, mandibular palp one-segmented with one seta. Distal endite of maxillula with five to seven claws. Maxilla four-segmented. Thoracopods I–VII with exopod of two to six articles. Male thoracopod VIII longer than wide; outer lobe rounded, trapezoidal or finger-like; basipod without setae; exopod and endopod small with or without setation or teeth-like setae. Sympod of the uropod with homonomous or non-homonomous spines; endopod of uropod with two terminal spines, inner spines, two or three plumose setae, two barbed terminal setae, and protrusion on disto-outer margin; exopod with or without basiventral seta. Furcal rami with few spines (six to 11).

Included species: Nicolenella abramsae Perina and Camacho sp. nov., N. cassidis ( Hong and Cho, 2009) comb. nov., N. floecknerae Perina and Camacho sp. nov., N. hueyi Perina and Camacho sp. nov., N. isabelleana Perina and Camacho sp. nov., N. mittrai Perina and Camacho sp. nov., N. morganae Perina and Camacho sp. nov., N. newtonorum Perina and Camacho sp. nov., N. nguyenae Perina and Camacho sp. nov., N. pilbaraensis ( Hong and Cho, 2009) comb. nov., N. rodmani Perina and Camacho sp. nov., N. vanweesae Perina and Camacho sp. nov.

Remarks: Nicolenella gen. nov. differs from Atopobathynella , Kimberleybathynella , Hexabathynella , Chilibathynella , and Onychobathynella by having the endopod of uropod without dagger/dagger+spines shape and exopod of thoracopods multi-segmented. It differs from the other Australian genera by the combination of characters listed in Table 5. This genus shares many characters with Brevisomabathynella and Billibathynella , including the multi-segmented exopods of thoracopods I–VII, the elongated ThVIII of the male, the small cone-shape ThVIII of female, endopod of uropod with more than 3 spines (for a complete comparison amongst species of Billibathynella , Brevisomabathynella and Nicolenella gen. nov. see Supplementary Material Table S2). Billibathynella differs from Nicolenella gen. nov. by bigger size, many teeth on labrum (more than 21), many claws on pars molaris of the mandible (more than 11), many articles of the exopod of thoracopods (more than five), many spines on the sympod of the uropod (more than 10), many setae on the exopod of the uropod (more than 12), many spines on the endopod of the uropod (more than five), and many spines on furca (more than 16). Brevisomabathynella has very subtle differences compare to Nicolenella gen. nov., such as: AII five-segmented, while Nicolenella gen. nov. has six or seven (however two species of the new genus have AII five-segmented), the number of articles on the exopod of ThsII to VI is five or more, the number of spines on the sympod of the uropod is 10 or more. Both, Billibathynella and Brevisomabathynella have dentate lobe on the male ThVIII absent. Further support for the erection of a new genus is the geographic separation of the three genera, with Billibathynella and Brevisomabathynella collected from the Gascoyne and Murchison regions, and Nicolenella gen. nov. from the Pilbara region ( Fig. 1 View FIGURE 1 ), and the molecular phylogeny that defines three well supported clades ( Fig. 2 View FIGURE 2 ). However, future sampling in poorly sampled regions could redefine the status of these three genera. The 10 species of Nicolenella gen. nov. have very subtle differences listed in Supplementary Material Table S2. Some major differences are the number of segments on AII (5 to 7), number of teeth on pars incisiva of the mandible (4/5), presence or absence of the inner seta on the first article of the endopod of ThsII to VII, homonomous or non-homonomous spines on sympod of uropod, presence or absence of a basiventral seta on the exopod of the uropod.

Etymology. This genus is dedicated to Nicole Coineau, who worked extensively on stygofauna, and described many species of Bathynellacea Chappuis, 1915 .