Nicolenella morganae Perina & Camacho, 2025

Nicolenella morganae Perina & Camacho , sp. nov.

( Figs. 26 View FIGURE 26 , 27 View FIGURE 27 , Appendix 7J)

urn:lsid:zoobank.org:act:

Material examined. Holotype male. AUSTRALIA: Western Australia: Gudai Darri, Pilbara, Bore MB19 K58W0001 ( stygo net haul), 22°31'52.1868"S, 119°00'20.0779"E, 19 September 2022, F. Rudin, A. Umbrello ( WAMC 82062 - BMR05159 View Materials - BES17166 , permanent slide). GoogleMaps

Paratypes: 1 juvenile, WAMC 82061 - BMR03368 View Materials - BES 10302 in ethanol, same detail as holotype, but collection date 2 November 2020, F. Rudin, M. Curran . 1 juvenile WAMC 82063 - BMR02728 View Materials - BES 8318 in ethanol, same detail as holotype, but collection date 11 March 2021, P. Runham, S. Floeckner .

Diagnosis. AI seven-segmented. AII six/seven-segmented, partial separation between article six and seven. Mandibular palp one-segmented formed by one long article and one seta that does not extend beyond the distal end of the pars incisiva. Distal endite of maxillula with six claws. Three to five articles on exopod of thoracopods. One internal seta on first article of endopod of ThII to VII. Male thoracopod VIII rectangular, about 1.5 times as long as wide. Sympod of the uropod with homonomous spines; exopod of the uropod slightly shorter than endopod, with three distal setae, two dorsal and one basiventral seta. Furca with few small inner spines and two strong distal ones. It differs from all other species of Nicolenella gen. nov. by the combination of characters listed in Supplementary Material TableS2. The sequenced specimens differ from all the other Nicolenella gen. nov., Billibathynella and Brevisomabathynella species sequenced by COI = 17.2–25.8% and 12S = 21.7–31.3% ( Table 3, Appendix 2,3).

Description male holotype (WAMC 82062). Body length of 1.2 mm. Body over five times as long as maximum width, elongated, almost cylindrical, segments slightly widening and lengthening towards posterior end of body (Appendix 7J).

Antennula ( Fig. 26A View FIGURE 26 ): seven-segmented, over two times longer than AII. The first article is the longest, followed by the second and third, which are similar in length and slightly longer than article sixth and seventh; fourth article slightly longer than article five, which is the shortest. Fifth article with two, and sixth and seventh articles with three terminal aesthetascs. Antennular setation as in Fig. 1A View FIGURE 1 .

Antenna ( Fig. 26B View FIGURE 26 ): seven-segmented; the first article is the shortest; second and third article short and similar in length, sixth and fifth similar in length and slightly shorter than article four and seven, which are the longest and similar in length. Separation between article six and seven not complete. Setal formula of AII: 0+0/0+0/1+1/1+1/0 +0/1+0/4(1).

Labrum ( Fig. 26C View FIGURE 26 ): concave, free edge with 17 teeth.

Paragnaths: absent.

Mandible ( Fig. 26D View FIGURE 26 ): 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 seta not reaching the distal end of the pars incisiva.

Maxillula ( Fig. 26E View FIGURE 26 ): proximal endite with four unequal claws; distal endite with six claws: two apical one smooth and the rest denticulated; three smooth, unequal subterminal setae on the outer distal margin.

Maxilla ( Fig. 26F View FIGURE 26 ): four-segmented, setal formula 3, 4, 9, 4.

Thoracopods I to VII ( Figs. 27A–G View FIGURE 27 ): length slightly increasing from thoracopod one to five, last two thoracopods shorter and similar in length. Epipod present in all thoracopods, about half or more than half length of the corresponding basipod. All basipods with one distolateral seta shorter than the first article of the endopod. Exopod slightly longer than the first two articles of the endopod in thoracopod I, exopod of ThII and VII slightly shorter than endopod, exopod of ThIII and VI as long as endopod, and exopod of ThIV and V slightly longer than endopod. Exopod of all thoracopods with two very long distal setae on each article. Number of exopodal segments of Ths I to VII: 3-4-4-4-4/5-4-4. Endopod four-segmented in all thoracopods. First article shorter than article two and three, which are similar in length, and fourth article small in all thoracopods; first and second article bearing an outer plumose seta, one smooth inner seta on article one and two smooth setae on article two in all thoracopods, except ThI that has two inner setae on the first article and three on the second one, and ThVII that has one inner seta on the second article on one side; third article with one outer distal seta on all thoracopods, and one inner seta on ThI ; fourth article very reduced with two strong claws of different length and two smooth seta on ThI to IV (but one side of ThIV has only one seta), and two claws and one seta on ThV to VII. Setal formula of endopods as follow:

ThI 2+1/3+1/1+1/4(2)

ThII, III 1+1/2+1/0+1/4(2)

ThIV 1+1/2+1/0+1/3(1) and 4(2)

ThV, VI 1+1/2+1/0+1/3(1)

ThVII 1+1/1,2+1/0,1+1/3(1)

Thoracopod VIII ( Fig. 26G,H View FIGURE 26 ): compact, longer than wider. Penial region with massive protopod. Outer lobe curved, reaching over the distal end of basipod. Inner lobe small, shorter than outer lobe. Basipod with frontal crest (or projection) and without setae. Exopod very small without setae, endopod slightly bigger with one seta.

Pleopod I ( Fig. 27H View FIGURE 27 ): one segmented with a long plumose seta.

Uropod ( Fig. 27I View FIGURE 27 ): sympod two times longer than endopod, and three and a half times as long as wide, with eight homonomous spines occupying about half of the length of the sympod. Endopod slightly longer than exopod, with two distal strong spines and one or two inner small spines, two dorsal plumose setae that exceed the tip of the endopod and two long distal barbed setae. Exopod with six barbed setae, two terminal, three dorsal, and one basiventral seta.

Pleotelson ( Fig. 27J View FIGURE 27 ): with one short lateral seta on each side; anal operculum not protruded.

Furca ( Fig. 27J View FIGURE 27 ): rami rectangular, with eight barbed spines, six short proximal ones and two long and strong distal ones. Two dorsal plumose setae, the inner one short and the outer one twice as long as the distal spine.

The female of this species is unknown.

Distribution and remarks. N. morganae sp. nov. has been collected in two bores at the Gudai-Darri area, in the Fortescue River Catchment ( Fig. 6 View FIGURE 6 , 9C View FIGURE 9 ). This species was previously known by Biologic Environmental Surveys as Parabathynellidae sp. “Biologic-PBAT053”. N. morganae sp. nov. can be distinguished by the combination of characters listed in Supplementary Material Table S2. It is sister to Parabthynellidae Lineage C ( N. sp. Marillana) ( Fig. 2 View FIGURE 2 ) collected about 20 km south in the Fortescue River Catchment ( Fig. 6 View FIGURE 6 ).

Etymology. The name of the species is dedicated to a colleague, Liesel Morgan, who has extensively worked on the genetics of Parabathynellidae .