Leiocanthus nagini Sørensen & Gąsiorowski & Randsø & Sánchez & Neves 2016, sp.
Creators: name: Sørensen, Martin V.
name: Gąsiorowski, Ludwik
name: Randsø, Phillip V.
name: Sánchez, Nuria
name: Neves, Ricardo C.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Cephalorhyncha
Kinorhyncha
Homalorhagida
Pycnophyidae
Leiocanthus
Leiocanthus nagini

description: Leiocanthus nagini sp. nov.
(Figs. 11–13)
Material examined. Holotype adult male, collected from sand with mud on 16 May 2014, at station SI-05 (Fig. 1, Table 1), at 52 m depth, at the locality “ Eastern Fairway ” southeast of Singapore Island (01°15.589’N 103°56.680’E), mounted in Fluoromount G, deposited at the Lee Kong Chian Natural History Museum, under catalogue number ZRC. MIS.0004. Additional, non-type material, includes one adult female, collected from sand with mud on 16 May 2014, at station SI-03 (Fig. 1, Table 1), at 9 m depth, between Bedok Jetty and Sungei Bedok in the southeast part of Singapore Island (01°18.387’N 103°57.591’E), and mounted for SEM.
Diagnosis. Leiocanthus without middorsal elevations. Paradorsal setae present on segments 2–9, paired ones on segment 4. Tergal anterior margin of segment 1 strongly denticulated and followed by a broad, ornamented area. Dorsal and ventral sides on segment 10 with longitudinal cuticular thickenings, visible with LM and SEM. Type 1 sensory spots present on segments 1–10, but not detectable on segment 11.
Etymology. The species name, nagini, is the female version of Nāgá – the Sanskrit word for a group of divine dragons or serpent deities known from Hindu and Buddhist mythology. Nagini is furthermore Lord Voldemort’s serpent, known from J. K. Rowling’s Harry Potter novels.
Description. The single specimen available for SEM was not suitable for introvert examinations, and detailed information on number and arrangement of scalids and oral teeth was thus not possible to obtain.
Neck with four dorsal and two ventral placids (Figs. 11A, B, 13A, B). All placids are thick and hard, with a depressed surface, and articulating with the anterior edge of the first trunk segment. Dorsal placids are rectangular and of similar size, whereas the ventral ones are broader and curve towards the lateral sides. Cuticular folds appear between dorsal and ventral placids. Trichoscalid plates are absent.
Trunk consisting of 11 segments (Figs. 11A, B, 12A, B). First segment with one tergal and three sternal plates (Figs. 11A, B, 13A, B); segments 2–11 with one tergal and two sternal plates (Figs. 11A, B, 12B). Dimensions and measurements of holotype are summarised in Table 6, and distribution of spines, sensory spots and setae in Table 7. The segment width is nearly constant along the trunk, reaching the maximum width at segment 5 and tapering slightly from this segment towards the posterior ones. Pachycycli of tergal and sternal plates are well-developed, with regular sized peg-and-socket joints from segments 2–10. Hairy tergosternal junctions, with numerous short cuticular hairs present on segments 2–10. Conspicuous, oval glandular cell outlets present in laterodorsal and ventromedial positions on segments 2–10 (Fig. 11A, B). Indistinct, rounded muscular scars present in laterodorsal and ventromedial positions on segments 2–10. One pair of laterodorsal and ventrolateral cuticular ridges present on segments 2–10. One pair of apodemes near the anterior margins of segments 9 and 10 (Fig. 11A).
Segment 1 with anterolateral margins of tergal plate projecting into horn-like extensions. Tergal, anterior margin of the segment strongly denticulated, followed by a broad, longitudinal cuticular ornamentation (Figs. 11B, 12E, 13A). Posterior margin of dorsal plate smooth, without middorsal structure specialisation (middorsal process or elevation) or intracuticular atria. Tergal plate with one pair of subdorsal glandular cell outlets, one pair of paralateral setae (Fig. 13B) and three pairs of sensory spots: one pair in subdorsal and two pairs in laterodorsal positions. Sensory spots on this and all following segments belong to type 1, which are rounded and small, consisting of several small cuticular papillae around a central collar of wider papillae. Ventral side with two episternal plates and one trapezoidal midsternal plate, the latter one overhanging the anterior edge of the segment (Figs. 11A, C, 13B). Anterior margin of each sternal plate is ornamented and followed by a contiguous depressed area (Fig. 13B). Each episternal plate with a glandular cell outlet in the medial region and two ventromedial sensory spots. Pectinate fringe on both dorsal and ventral sides thin, only visible with SEM. Conspicuous parallel, cuticular wrinkles present in the posterior parts of tergal and episternal plates, but absent in the midsternal one.
Segment 2 without middorsal elevation or intracuticular atria at the posterior margin of the dorsal plate. Tergal plate with a single paradorsal seta, and paired setae in laterodorsal and lateroventral positions. Paired sensory spots present in subdorsal and laterodorsal positions. Dorsal side with short secondary pectinate fringes in the anterior part of the segment, present from the tergosternal junction to the laterodorsal longitudinal ridge. Sternal plates with one pair of ventromedial sensory spots. Males with a pair of thick ventromedial tubes (Fig. 11A). Females instead with a pair of ventrolateral setae (Figs. 11C, 12F). Ventral side with secondary pectinate fringe similar to that on the dorsal side, stretching from the tergosternal junction to the ventromedial cuticular ridge. Posterior margin of tergal and sternal plates with conspicuous parallel, cuticular wrinkles. Tergosternal junctions with numerous short cuticular hairs. Muscular scars and glandular cell outlets present in laterodorsal and ventromedial positions. Pachycycli of tergal and sternal plates well-developed, with regular sized peg-and-socket joints. Pectinate fringe as on the preceding segment.
Segment 3 without middorsal elevation or associated intracuticular atria on tergal plate. A single paradorsal seta, one pair of laterodorsal setae, and two pairs of laterodorsal sensory spots are present on tergal plate. Both pairs of laterodorsal sensory spots are located mesially to the laterodorsal setae. Lateroventral setae absent. Sternal plates with one pair of ventromedial setae and sensory spots, with the sensory spots located lateral to the setae (Fig. 12F). Otherwise similar to preceding segment.
Segment 4 without middorsal elevation or associated intracuticular atria on tergal plate. Paired setae present in paradorsal, laterodorsal and lateroventral positions. Three pairs of sensory spots present, one in subdorsal and two in laterodorsal positions, all of them located mesially to the laterodorsal setae. Sternal plates as on segment 3. Otherwise similar to preceding segments.
Segment 5 with tergal plate (Fig. 13C) almost similar to that of segment 3 (Fig. 11B), but only with a single pair of laterodorsal sensory spots. Sternal plates similar to those on segment 3, except for the presence of paired ventrolateral setae. Otherwise similar to preceding segments.
Segment 6 with tergal plate (Figs. 11B, 12D, 13C) almost similar to that of segment 4, but with a single paradorsal seta. Sternal plates same as those of segment 3, but with the ventral setae in females displaced to a ventrolateral position (Figs. 11A, 13D). Otherwise similar to preceding segments.
Segment 7 with tergal and sternal plates (Figs. 11A, B, 12D, 13D) almost as those of segment 5, except for the ventral setae that are displaced to a ventrolateral position (Figs. 11A, 13D). Otherwise similar to preceding segments.
Segment 8 with tergal plate (Figs. 11B, 12C, 13F) similar to that of segment 6, but with one additional pair of laterodorsal sensory spots, making it three laterodorsal pairs in total (Fig. 11B). Sternal plates as those on segment 3. Otherwise similar to preceding segments.
Segment 9 with tergal (Figs. 11B, 12C, 13F) and sternal plates similar to those of segment 3. Protonephridial opening in paralateral position, with the pore surrounded by a few short cuticular hairs; opening not sieve-like. Paired apodemes (or anteromesial thickenings of ventral pachycycli) present near the anterior margin of segment (Fig. 11A). Otherwise similar to preceding segment.
Segment 10 without dorsal structures (Figs. 11B, 12G). Tergal plate with one pair of lateroventral setae and a pair of laterodorsal sensory spots. Sternal plates with ventrolateral setae. Ventromedial sensory spots not found. Paired apodemes present near the anterior margin of the segment (Figs. 11A, 13E). Lateral margins of tergal and sternal plates with conspicuous, longitudinal cuticular thickening visible with LM and SEM (Figs. 12G, 13E). Otherwise similar to preceding segment.
Segment 11 with a pair of lateral terminal spines (Fig. 11A, B, D). Males with two pairs of penile spines and genital pores surrounded by a tuft of long hairs. Posterior segment margin with characteristic, irregularly fringed shape (Fig. 13E).
description: Published as part of Sørensen, Martin V., Gąsiorowski, Ludwik, Randsø, Phillip V., Sánchez, Nuria & Neves, Ricardo C., 2016, First report of kinorhynchs from Singapore, with the description of three new species, pp. 3-27 in Raffles Bulletin of Zoology 64 on pages 20-25, DOI: 10.5281/zenodo.4502533