Thetispelecaris kumejimensis, Shimomura, Michitaka, Fujita, Yoshihisa & Naruse, Tohru, 2012

Shimomura, Michitaka, Fujita, Yoshihisa & Naruse, Tohru, 2012, First record of the genus Thetispelecaris Gutu & Iliffe, 1998 (Crustacea: Peracarida: Bochusacea) from a submarine cave in the Pacific Ocean *, Zootaxa 3367, pp. 69-78 : 70-78

publication ID	https://doi.org/ 10.5281/zenodo.281672
DOI	https://doi.org/10.5281/zenodo.6180691
persistent identifier	https://treatment.plazi.org/id/038787F2-E748-C76C-FF49-DB1AB5DD7EF3
treatment provided by	Plazi
scientific name	Thetispelecaris kumejimensis
status	sp. nov.

Treatment

Thetispelecaris kumejimensis View in CoL n. sp.

( Figs. 1–5 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 )

Material examined. Holotype: 1 non-ovig. Ƥ, 1.1 mm ( KMNH IvR 500,497), paratypes: ovig Ƥ, 1.4 mm ( KMNH IvR 500.498); 2 non-ovig. Ƥ, 0.9 mm (RUMF-ZC-1134, 1135). KUMEJIMA 2009 stn. Diving 10, submarine cave “Shoggako-oki”, off western part of Kumejima Island, Ryukyu Islands, Japan, 12 November 2009.

Diagnosis. Carapace 1.1 times as long as wide; antennal scale with 3–4 setae; maxilliped dactylus with 4 slender setae; basis of pereopod 1 with 2 long setae ventrodistally; basis and ischium of pereopods 3–6 partly fused; exopod of pereopods 4 and 5 with 4-segmented; and pleopods 4 and 5 with 2 setae apically.

Description of holotype and paratype (KMNH IvR 500,498). Body ( Figs. 1 View FIGURE 1 A, 2A) nearly cylindrical, somewhat depressed. Cephalothorax ( Fig. 1 View FIGURE 1 A) subpentagonal in dorsal view, slightly longer than wide, without setae; rostrum produced anteroventrally, acutely pointed at tip. Pereon ( Figs. 1 View FIGURE 1 A) shorter than pleon; first pereonite narrower than cephalothorax, shortest and narrowest; second pereonite produced anterolaterally, 2.4 times as long as first pereonite; third to sixth pereonites subequal in width; third pereonite 3.5 times as long as first pereonite; fourth to seventh pereonites gradually decreasing in length posteriorly; fourth pereonite longest, 5 times as long as first pereonite; fifth pereonite 4.8 times as long as first pereonite; sixth pereonite 4 times as long as first pereonite; seventh pereonite as long as sixth pereonite. First to fifth pleonites ( Fig. 1 View FIGURE 1 A) gradually decreasing in width posteriorly; first to fourth pleonites gradually increasing in length posteriorly; sixth pleonite expanded posterolaterally; telson ( Figs. 1 View FIGURE 1 A, 5A) shorter than sixth pleonite, 0.8 times as long as wide, bearing 4 pairs of simple setae laterally, pair of simple setae terminally and pair of slender setae dorsally; anus ( Fig. 2 View FIGURE 2 A) located ventrodistally, with lateral valves.

Antennule ( Fig. 1 View FIGURE 1 A, B) anteriorly directed, with 3-segmetned peduncle and 4-segmented inner and outer flagella; first peduncular segment longest and widest, with 2 lateral, medial and 2 dorsal simple setae, and with setules; second peduncular segment 0.6 times as long as first segment, with 2 distolateral, 3 distomedial simple setae and setules; third peduncular segment pentagonal, 0.9 times as long as second segment, with short distolateral, 4 long lateral and simple distomedial setae, and with setules. Inner flagellum ( Fig. 1 View FIGURE 1 B) 1.4 times as long as outer flagellum; setal formula 1, 2, 1, 3. Outer flagellum ( Fig. 1 View FIGURE 1 B); setal formula 0, 0, 0, 4; aesthetasc present on second and third segments.

Antenna ( Fig. 1 View FIGURE 1 A, C) with 2-segmented protopod (peduncle), unisegmented scaphocerite (exopodal scale), and 8-segmented endopodal flagellum. First protopodal segment (coxa) unarmed; second segment (basis) 1.7 times as long as coxa, 3 times as long as exopodal scale, with some setules. First endopodal segment shortest; second endopodal segment 3 times as long as first segment; third endopodal segment 0.8 times as long as second segment; forth to eighth endopodal segments combined 0.7 times as long as first to third endopodal segments combined; setal formula of endopodal segments 1, 4, 6, 0, 3, 3, 1, 4.

Labrum ( Fig. 2 View FIGURE 2 B) as long as wide, with numerous spinular rows on anterior surface; terminal portion truncate, slightly concave midway.

Mandibles ( Fig. 2 View FIGURE 2 F, G) comprising coxa with well-developed gnathobase and 3-segmented palp. Coxal gnathobases complex in structure: incisor and molar processes widely separate; incisors with 2 cusps apically; molar processes protruded from gnathobase, heavily chitinized terminally, with several lamellar plates and grinding surface. Left mandibular incisor ( Fig. 2 View FIGURE 2 F) with lacinia mobilis bearing spinules subterminally, with short simple and 3 spinulose setae near lacinia mobilis, and with 9 curved setae and some short setae originating from round protuberance; mandibular palp 3-segmented, slender; segment 1 small, without setae; segment 3 longest, with 3 spinulose setae at tip. Right mandibular incisor ( Fig. 2 View FIGURE 2 G) with 2 spinulose, 7 curved and some short setae originating from round protuberance; segment 3 of mandibular palp with 2 spinulose setae apically.

Paragnath ( Fig. 2 View FIGURE 2 C) bilobed; each lobe tapering distally, terminating in elongate hirsute projection; each lobe with inner round projection and 2 stout spines of unequal length midway.

Maxillule ( Fig. 2 View FIGURE 2 D, E) lacking palp, comprising two segments, coxa and basis, each forming distinct endite, with numerous rows of minute spinules; coxal endite curved inward near its base, with 2 comb-like, 2 simple and 1 spinulose setae distally; basal endite curved inward at midlength, with 2 dorsal spinulose, some lateral setules and 2 groups of marginal elements, proximal group of which consisting of 6 chitinized spines and few setules, distal group of 5 short comb-like, 3 long comb-like and simple setae.

Maxilla ( Fig. 2 View FIGURE 2 H) with quadrate coxa bearing 20 spiniform setae medially and spinulose seta ventrally, and with setules laterally and ventrally; distal inner corner with 6 spinulose and 3 simple setae; distal outer corner with long plumose seta near base outer lobe. Inner lobe with approximately 15 rake-like, blunt setae and setules; outer lobe 2 with approximately 21 rake-like, blunt setae.

Maxilliped ( Fig. 2 View FIGURE 2 I) with elongate basis with many setules on ventral surface and 2 groups of marginal elements; proximal group consisting of 4 straight spinulose and 5 curved spinulose setae; distal group of 10 stout setae of various ornamentations and 2 simple and comb-like setae. Palp 5-segmented, longer than basis, ischium small, unarmed; merus about twice as long as ischium, with simple seta distally and setules laterally; carpus as long as proximal 2 segments combined, with 3 simple setae laterally and 2 long simple setae distally, and with setules; propodus 0.7 times as long as carpus, with 6 simple setae distally, without setules; dactylus 0.6 times as long as propodus, with 4 simple setae terminally.

Pereopod 1 ( Figs. 2 View FIGURE 2 A, 3A) longest of pereopods, directed anterolaterally, modified into mouthpart appendage; basis curved dorsally, with 2 simple and plumose setae ventrally and setules; ischium 0.4 times as long as basis, with simple seta ventrally; merus triangular, with simple seta dorsodistally and 2 simple setae ventrally; carpus shorter than basis, with 2 long simple setae ventrally and setules; propodus as long as carpus, with short seta dorsally, 2 long setae distally and simple seta ventrally, and with setules; dactylus stout spine and long seta terminally, short spine and 3 setae subterminally, and with setules; exopod short, 2-segmented, setal formula 1, 2.

Pereopod 2 ( Figs. 2 View FIGURE 2 A, 3B) thickest of pereopods, covered entirely with setules; basis protruding ventrodistally, bearing 3 long simple setae on its tip, and with short simple seta dorsally and setules; ischium quadrate, 0.3 times as long as basis, with 2 simple setae ventrally and setules; merus trapezoidal, slightly longer than ischium, with 3 simple setae dorsodistally and 2 simple setae ventrodistally; carpus twice as long as merus, with 2 simple setae dorsodistally and 2 stout setae ventrally; propodus 0.8 times as long as carpus, with short serrate, 2 stout, simple setae dorsally and 2 stout setae ventrally; dactylus slender, slightly longer than propodus, with 2 stout and simple setae apically and short seta subapically; exopod 3-segmented, setal formula 1, 1, 2.

Pereopod 3 ( Figs. 2 View FIGURE 2 A, 3C) shorter than pereopod 2; basis with long and 3 short simple setae ventrodistally and long plumose setae ventrally; ischium 0.4 times as long as basis, with 2 simple setae ventrally; merus slightly longer than ischium, with simple seta laterally and ventrally; carpus 1.2 times as long as merus, with 2 simple setae laterally, 3 simple setae dorsally and 3 simple setae ventrally; propodus as long as carpus, with 2 short and 4 long simple setae dorsodistally and 2 stout and 2 simple setae ventrally; dactylus slender, 0.8 times as long as propodus, with short simple seta dorsally and ventrally, and with 2 long and short simple setae apically; exopod 4-segmetned, setal formula 1, 1, 1, 2. Epipod ( Fig. 5 View FIGURE 5 C) with 6 marginal plumose setae.

Pereopod 4 ( Figs. 2 View FIGURE 2 A, 4A); basis 3 long plumose and 3 simple setae ventrally; ischium with short simple seta ventrally; merus with 2 simple setae ventrally; carpus as long as merus, with 2 simple setae dorsally and 3 simple setae ventrally; propodus as long as carpus, with 3 simple setae dorsally and 2 simple setae ventrally; dactylus 0.4 times as long as propodus, with 2 long and short simple setae apically; exopod 4-segmeted, setal formula 1, 1, 1, 1, 2. Epipod ( Fig. 5 View FIGURE 5 D) with 10 marginal plumose setae.

Pereopod 5 ( Figs. 2 View FIGURE 2 A, 4B); similar to preceding leg; basis with 3 long plumose setae ventrally; ischium with simple seta ventrodistally; merus with 2 simple setae ventrally; carpus slightly longer than merus, with simple seta dorsodistally and 4 simple setae ventrally; propodus as long as carpus, with 5 long simple setae dorsodistally and simple seta ventrally; dactylus 0.7 times as long as propodus, with 2 simple setae apically; exopod 4-segmetned, setal formula 1, 1+1, 1, 2. Epipod ( Fig. 5 View FIGURE 5 E) with 11 marginal plumose setae.

Pereopod 6 ( Figs. 2 View FIGURE 2 A, 4C); basis with simple seta dorsally and long plumose, 2 simple setae ventrally; ischium with simple seta distally; merus with simple seta dorsodistally and ventrodistally; carpus slightly longer than merus, with simple seta dorsodistally and 2 simple setae ventrally; propodus 1.8 times as long as carpus, with simple seta and row of setules ventrally; dactylus 1.1 times as long as propodus, with long simple seta dorsally and long and short simple setae apically; exopod 4-segmented, setal formula 1, 0, 1+1, 2. Epipod ( Fig. 5 View FIGURE 5 F) with 12 marginal plumose setae.

Pereopod 7 ( Figs. 2 View FIGURE 2 A, 4C) shortest of pereopods; basis with 2 simple setae dorsally and simple seta ventrally; ischium unarmed; merus trapezoidal, as long as ischium, with 2 simple setae ventrodistally; carpus 1.4 times as long as merus, with simple seta dorsodistally; propodus 1.5 times as long as carpus, with 2 long simple setae dorsodistally and 3 short simple setae ventrally; dactylus half as long as propodus, with long stout seta apically and 2 short setae subapically, and with setules dorsally and ventrally.

Pleopods 1–3 ( Fig. 2 View FIGURE 2 A) rudimentary, represented by triangular lobe with terminal seta; pleopods 4 and 5 ( Figs. 2 View FIGURE 2 A, 5B) distinctly articulated at base, unisegmented, bearing lateral and 2 apical short setae.

Uropod ( Figs. 1 View FIGURE 1 A, 2A, 5A) biramous; protopod 2.3 times as long as wide, with 3 lateral, dorsal simple setae and mediodistal spinulose seta. Exopod 2-segmented; segment 1 0.8 times as long as protopod, with 2 distolateral and distomedial setae; segment 2 slender than segment 1, slightly shorter than segment 1, with 1 lateral, 2 medial and 3 apical plumose setae. Endopod 5-segmented; segment 1 with 4 lateral simple and distomedial spinulose setae; segment 2 0.7 times as long as segment 1, with 2 lateral simple and distomedial spinulose setae; segment 3 1.4 times as long as segment 2, with distolateral plumose and distomedial spinulose setae; segment 4 as long as segment 3, with distolateral plumose and distomedial spinulose setae; terminal segment longest, 1.7 times as long as segment 4, with distolateral, distomedial and 3 apical plumose setae and distomedial spinulose seta.

Variation. The paratype females agree with the holotype in most characters (excluding oostegites). However, variation was observed in the number of setae of the antennal scales: 4 setae in holotype and paratypes (KMNH IvR 500,498, RUMF-ZC-1135) and 3 setae in paratype (RUMF-ZC-1134).

Etymology. The new species is named after the type locality.

Remarks. Thetispelecaris kumejimensis n. sp. resembles T. remex Gutu & Iliffe, 1998 , from anchihaline and submarine caves in Bahamas, in having 4-segmented exopod of pereopods 4 and 5; and separated basis and ischium of pereopod 3. The two species, however, differ from one another in the following combination of features (those of T. remex in parentheses): carapace 1.1 times as long as wide (1.2 times as long as wide); maxilliped dactylus with 4 slender setae (3 slender setae); basis of pereopod 1 with 2 long setae ventrodistally (1 long and 2 short setae); basis and ischium of pereopods 4–6 partly fused (separated); and pleopods 4 and 5 with 2 setae apically (3 setae).

The present species differs from Thetispelecaris yurikago Ohtsuka, Hanamura & Kase, 2002 , from a submarine cave on Grand Cayman Island, Caribbean Sea, in the following features (those of T. yurikago in parentheses): carapace 1.1 times as long as wide (1.3 times as long as wide); antennal scale with 3–4 setae (6 setae); maxilliped dactylus with 4 slender setae (3 spiniform and 2 fine setae); basis of pereopod 1 with 2 long setae (without setae); exopod of pereopods 4 and 5 with 4-segmented (5-segmented); and basis and ischium of pereopod 3 separated (partly fused).