Tenagopelta pacifica Ng & Castro, 2016, n. sp.
Creators: name: Ng, Peter K. L.
name: Castro, Peter
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Chasmocarcinidae
Tenagopelta
Tenagopelta pacifica

description: Tenagopelta pacifica n. sp.
(Figs. 17 A, B; 26F; 33G; 42I; 47A, B; 54F; 61E; 79A‒E; 88C; 91G; 102)
Hephthopelta sp.— Serène & Vadon 1981: 118, 119, 120, 123 [Philippines] Hephthopelta cf. lugubris — Komai et al. 2012: 149, fig. 7 [Philippines].
Type material. Holotype male (11.0 × 12.8 mm) (NMCR) [photographed], Philippines, Bohol Sea, Maribojoc Bay, 100‒300 m, P.K.L. Ng coll., 11.2003‒04.2004.
Paratypes: 1 male (10.7 × 11.2 mm) (USNM 46387), 1 female (10.7 × 11.7 mm) (USNM 46386); 1 female (7.6 × 8.0 mm) (USNM 46385), Philippines, South China Sea, near Luzon, Albatross, stn 5278.—PANGLAO 2004: 1 female (ZRC 2015.218), Philippines, Balicasag I., P.K.L. Ng coll., 29.05.2004; 1 male (10.2 × 11.4 mm) (ZRC 2015.212) [G1 drawn], Maribojoc Bay, 100‒300 m, P.K.L. Ng coll., 11.2003‒04.2004; 2 males, 2 females (ZRC 2015.213), Maribojoc Bay, 100‒300 m, P.K.L. Ng coll., 11.2003‒04.2004.—PANGLAO 2005: 1 female (ZRC 2015.202), Philippines, Bohol / Sulu Sea, stn CP2363, 09°06.0’N, 123°25.0’E, 437–439 m, 26.05.2005; 1 female (ZRC 2015.201), Bohol Sea, off Balicasag I., stn CP2394, 09°29’N, 123°40'E, 470–566 m, 30.05.2005; 1 female (8.2 × 9.3 mm) (ZRC 2015.197), Bohol Sea, Maribojoc Bay, stn CP2395, 09°36.2’N, 123°43.8’E, 382–434 m, 31.05.2005; 1 female (9.2 × 10.4 mm) (ZRC 2015.187) [photographed], Bohol Sea, Maribojoc Bay, stn CP2397, 09°35’N, 123°42'E, 642–669 m, 31.05.2005; 2 juveniles, 6 males, 9 females (ZRC 2015.190), Bohol Sea, Maribojoc Bay, stn CP2407, 09°41’N, 123°48'E, 256–268 m, 01.06.2005; 1 male, 1 ovigerous females, 2 females (QM, ex ZRC), Bohol Sea, Maribojoc Bay, stn CP2408, 09°43.5’N, 123°47.1’E, 121–137 m, 01.06.2005; 1 male (ZRC 2015.199), Bohol Sea, Maribojoc Bay, stn CP2409, 09°44.8’N, 123°44.8’E, 220–257 m, 01.06.2005; 1 female (6.6 × 6.9 mm) (ZRC 2015.200) [photographed], Bohol I., Cortes, stn T15, 09°41.2’N, 123°49.0’E, 180 m, 24.06.2004. — AURORA 2007: 1 female (6.3 × 6.8 mm) (MNHN-IU-2014-12808 ZRC 2015.208) [photographed], northwestern Philippines, stn CP2656, 16°02.01’N –16°01.7’N to 121°52.02’E–121°53.9’E, 262‒278 m, 20.05.2007; 1 juvenile (ZRC 2015.207), stn CP2666, 15°56.35’N–15°57.65’N to 121°43.67’E–121°45.31’E, 184‒199 m, 02.05.2007; 1 female (8.2 × 9.4 mm) (MNHN-IU-2014-12809, ex ZRC 2015.203), stn CP2667, 15°56.81’N–15°54.52’N, 121°46.97’E–121°46.44’E, 280‒292 m, 292 m, 21.05.2007; 1 male (10.5 × 11.8 mm), 1 female (8.4 × 9.3 mm) [photographed] (ZRC 2015.193), stn CP2717, 14°29.96’N–14°28.94’N to 121°41.67’E– 121°43.13’E, 311‒362 m, 29.05.2007; 9 males, 3 females, 3 ovigerous females (ZRC 2015.194), stn CP2717, 15°04.36’N–15°04.06’N to 121°42.75’E–121°41.06’E, 368‒484 m, 29.05.2007; 2 males (8.0 × 9.0 mm, 8.0 × 9.1 mm), 1 female (7.2 × 7.9 mm) (ZRC 2015.192), stn CP2715, 14°31.50’N–14°33.09’N to 121°42.14’E– 121°42.05’E, 244‒249 m, 29.05.2007; 2 males, 2 females (10.0 × 11.4 mm) [photographed] (ZRC 2015.219), stn CP2716, 14°32.14’N–14°30.41’N to 121°40.80’E–121°41.16’E, 298‒356 m, 29.05.2002; 2 females (ZRC 2015.204), stn CP2718, 14°29.93’N–16°28.63’N to 121°46.72’E–121°97.56’E, 200‒220 m, 29.05.2007; 3 males (MNHN-IU-2014-12810, ex ZRC 2015.206), stn CP2719, 14°27.84’N–14°26.47’N to 121°47.90’E–121°48.36’E, 155‒204 m, 29.05.2007; 6 males, 7 females (ZRC 2015.195), stn CP2720, 14°25.30’N–14°26.63’N to 121°47.70’E—121°46.68’E, 256‒301 m, 29.05.2007; 5 males, 9 females (ZRC 2015.191), stn CP2721, 14°24.03’N–14°26.26’N to 121°46.83’E—121°47.56’E, 340‒360 m, 29.05.2007; 3 males, 2 females, 2 ovigerous females (MNHN-IU-2014-12811, ex ZRC 2015.196), stn CP2722, 14°24.45’N–14°25.80’N to 121°47.90’E— 121°46.19’E, 291‒338 m, 29.05.2007; 1 female (ZRC 2015.205), stn CP2734, 15°56.41’N–15°56.98’N to 121°48.71’E–121°49.21’E, 453‒460 m, 01.06.2007; 1 male (ZRC 2015.188), stn CC2746, 15°58.78’N– 15°56.63’N to 121°46.44’E–121°44.85’E, 182‒220 m, 0 2.06.2007.
Other material examined. Philippines. Hakuho-maru: 1 female (CBM-ZC 8770), Sulu Sea, stn SA-2, 10°36.48’N, 121°31.56'E, 362‒372 m, S. Ohtsuka coll., 08.12.2002.—MUSORSTOM 1: 4 males, 3 females (MNHN-IU-2013-15775, ex MNHN B-10501), stn CP25, 14°02’N, 120°18’E, 191‒200 m, 22.03.1976.— MUSORSTOM 2: 2 males (MNHN-IU-2013-9054), stn CP21, 14°02’N, 120°17’E, 191‒192 m, 22.11.1980; 1 male, 1 female (MNHN-IU-2013-9055), stn CP69, 14°07’N, 120°03’E, 1800‒1950 m, 30.11.1980.— MUSORSTOM 3: 2 males, 2 females (MNHN-IU-2013-9052), 1 ovigerous female, stn CP99, 14°01’N, 120°18’E, 196‒204 m, 01.06.1985.— PANGLAO 2005: 2 young females (smaller 6.9 × 7.7 mm) (ZRC 2015.198) [photographed], Bohol Sea, Maribojoc Bay, stn CP2332, 09°39’N, 123°46'E, 396–418 m, 22.05.2005; 2 males, 1 female (all badly damaged) (ZRC 2015.189) [photographed], Bohol Sea, off Pamilacan I., stn CP2348, 09°30’N, 123°52'E, 196–216 m, 24.05.2005;
Indonesia. 2 males (larger 12.2 × 14.3 mm), 3 females (largest 10.7 × 13.1 mm) (MNHN-IU-2013-9053), CORINDON 1, Makassar Strait, stn 273, 01°56.0’S, 119°16.0’E, 220‒ 180 m, 0 7.11.1980.
Diagnosis. Carapace (Figs. 17 A, B; 102) subtrapezoidal, globose, 1.0–1.2 wider than long, margins with short setae; front bilobed, with shallow median cleft; anterolateral margins arcuate, without distinct lobes or teeth. Posterior margin of epistome (Fig. 26 F) with broad semicircular median lobe with deep median fissure, semicircular lateral margins. Eye peduncle (Fig. 26 F) filling orbit, short, mobile; cornea reduced, pigmented. Third maxilliped (Fig. 33 G) merus quadrate, ischium rectangular, about same length as merus. Chelipeds (Figs. 17 A, B; 47A, B; 102) subequal in length, slightly dissimilar in females, heteromorphic in males; fingers of minor chela (Fig. 47 B) subcircular in cross-section, not distinctly laterally flattened, gently tapering to tip, scissor-like, cutting margins with distinct sharp teeth; major chela of males (Fig. 47 A) with enlarged dactylar teeth. Ventral surface of cheliped merus with 3 large, conspicuous teeth (sometimes additional small teeth or large tubercles) on outer margin in both sexes (Fig. 42 I). Outer surface of adult male major chela with prominent swelling on median surface adjacent to dactylus (Fig. 102 B). Inner margin of cheliped carpus with long distal tooth (Fig. 17 A, B). Inner margin of basis-ischium of adult major cheliped gently granuliform (Fig. 17 A). Long setae along margins of fingers, distal portion of cheliped propodi, dactyli, propodi of ambulatory legs. Proportionally long ambulatory legs (Fig. 17 A, B). Meri of ambulatory legs with microscopic granules. P5 dactylus slightly upcurved (Figs. 17 B; 102A, C, D, F); merus 0.8 cl. Fused thoracic sternites 1, 2 (Fig. 54 F) semicircular, broad, short; fused thoracic sternites 3, 4 broad (Figs. 54 F; 88C; 91G). Male pleon (Figs. 54 F; 61E) with proportionally short telson. Sterno-pleonal cavity deep, press-button for pleonal holding as small, short tubercle posterior to thoracic sternal suture 4/5 near edge of sterno-pleonal cavity. Male thoracic sternite 8 short, rectangular; “supplementary plate” long, subovate; structures separated by relatively wide gap with most of the penis exposed (e.g., Fig. 61 E). G1 (Fig. 79 A‒D) with stout basal part; distal two-thirds long, tapering, with short spinules; tip subtruncate. G2 (Fig. 79 E) longer than G1, straight, distal segment slender, directed inwards. Somites of female pleon (Fig. 88 C) with convex lateral margins; telson proportionally short. Sterno-pleonal cavity of female (Fig. 91 G) deep. Vulvae widely separated on outer margins of cavity close to suture 5/6.
Colour. The carapace of adult specimens is white to light brown with white pereiopods in life (Fig. 102 A‒C). Younger specimens have carapaces that vary from light brown to bright pink (Fig. 102 D‒F), with smallest specimens possessing pink pereiopods as well (Fig. 102 F).
Etymology. The epithet pacifica denotes the distribution of the new species in the Pacific Ocean in contrast to the Indian Ocean distribution of its two congeners.
Remarks. Specimens reported as “ Hephthopelta sp.” by Serène & Vadon (1981: 123) from the western Philippines are almost certainly Tenagopelta pacifica n. sp. as we have material from MUSORSTOM 1 and 2 that were referred to this species. The specimens on hand (including USNM specimens from Philippines identified by M.J. Rathbun) are remarkably consistent in all the diagnostic characters, with all of them possessing three welldeveloped, sharp teeth or pointed tubercles on the ventral, outer margins of the cheliped merus. The swelling on the median outer surface of the major chela adjacent to dactylus is most prominent in large males (e.g., Fig. 102 B), being less distinct but still discernible in smaller ones.
Tenagopelta pacifica n. sp. is close to T. potens (Davie & Richer de Forges, 2013) from Papua New Guinea, northeastern Australia and New Caledonia in its carapace form and proportions of the ambulatory legs. The most effective way to separate them is by their G1 structures; in T. pacifica n. sp., the distal two-thirds is elongated and relatively slender (Fig. 79 A), whereas the distal half of the G1 is distinctly shorter and stouter (Fig. 79 K–N) in T. potens.
The specimens from the Makassar Straits in Indonesia (MNHN-IU-2013-9053) are referred to T. pacifica at present as they best agree with this species. The G1 is slightly shorter but essentially similar and can easily be explained by variation. The swelling on the outer surface of the male major chela is relatively lower and less pronounced compared to similar sized specimens from Philippines but this may also be due to variation.
Distribution. Western Pacific Ocean (Philippines, Indonesia). Depth: 100– 669 m.
description: Published as part of Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), pp. 1-182 in Zootaxa 4209 (1) on pages 79-82, DOI: 10.11646/zootaxa.4209.1.1, http://zenodo.org/record/272646