Angustopelta aurita Rathbun 1932, n. comb.
Creators: name: Ng, Peter K. L.
name: Castro, Peter
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Decapoda
Chasmocarcinidae
Angustopelta
Angustopelta aurita

description: Angustopelta aurita (Rathbun, 1932) n. comb.
(Figs. 11 A‒C; 24C, D; 31D, E; 41A, B; 42H; 52D; 59D; 73A‒E; 87B; 91B; 101A‒D)
Hephthopelta aurita Rathbun, 1932: 34 [type locality: Japan, Suruga Bay].— Yokoya 1933: 201, fig. 67 [Japan].— Sakai 1939: 575; 1976: 551, pl. 194, fig. 4 [Japan].— Serène 1964a: 240 [in list], 241, 242 [in key]; 1968: 92 [in list].— Takeda 1997: 247 [Japan].— Serène & Vadon 1981: 119, 123, 127 [Philippines].—Ng et al. 2008: 76 [in list].
Hephthopelta sp.—Ng et al. 2008: fig. 61 [colour; Philippines].
Type material. Holotype: female (18.9 × 19.1 mm) (USNM 46405), Japan, Suruga Bay, Albatross, Suruga Bay, 11.7 mi [= 18.8 km] off Omai Saki Light, stn 5072, 34°44’55”N, 138°22’20”E, 271‒520 m, 16.10.1906.
Other material examined. Philippines. PANGLAO 2005: 1 male (7.7 × 9.5 mm), 1 female (10.8 × 12.3 mm) (ZRC 2015.248), [photographed], Bohol Sea, stn CP2353, 09°25.6’N, 124°06.5’E, 1750‒1767 m, 25.05.2005; 2 females (ZRC 2015.249) [photographed], Bohol Sea, stn CP2354, 09°26.0’N, 124°06.5’E, 1769‒1773 m, 25.05.2005; 1 male (9.6 × 11.2 mm) (ZRC 2015.250) [photographed], 1 female (ZRC 2015.251) [photographed], Bohol Sea, stn CP2355, 09°24.3’N, 124°10.7’E, 1764‒1775 m, 25.05.2005; 2 females (ZRC 2015.252), Bohol Sea, stn CP2357, 09°20.1’N, 124°03.8’E, 1760‒1762 m, 25.05.2005; 1 female (9.0 × 10.3 mm) (ZRC 2015.253), Bohol Sea, stn CP2389, 09°27.9’N, 123°38.4’E, 784‒786 m, 30.05.2005.
Indonesia. Makassar Strait. CORINDON 2: 2 males (MNHN-IU-2013-9050), stn CH276, 01°54.6’S 119°13.8’E, 456– 395 m, 08.11.1980.— Tanimbar and Kai Is. KARUBAR: 1 female (MNHN-IU-2013-9087), stn CP69, 08°42’S, 131o53’E, 356‒368 m, 02.11.1991; 1 male, 3 females (MNHN-IU-2013-9086), stn CP87, 08°47’S, 130°41’E, 1017‒1024 m, 05.11.1991; 1 male (MNHN-IU-2013-9089), stn CP89, 08°39’S, 131°08’E, 1084‒ 1058 m, 05.11.1991; 1 male, 1 female (MNHN-IU-2013-9088), stn CP91, 08°44’54”S,131°03’10”E, 884‒890 m, 0 5.11.1991.
Diagnosis. Carapace (Figs. 11 A‒C; 101A‒D) subtrapezoidal, gently convex; front bilobed, with shallow median cleft; anterolateral margins arcuate, minutely granular, with large, conspicuous tooth on anterolateral margin; posterolateral margins distinctly diverging. Epistome (Fig. 24 C, D) broad, semicircular median lobe with median fissure, semicircular lateral margins. Eye peduncle (Fig. 24 C, D) filling orbit, short, immobile; cornea reduced, pigmented. Third maxillipeds (Fig. 31 D, E) not filling buccal cavern when closed; merus subcircular, outer margin rounded, slightly elevated, anteroexternal angle rounded; ischium subquadrate, about same length as merus. Chelipeds (Figs. 11 A‒C; 41A, B; 101A‒D) subequal in length, slightly dissimilar in female, heteromorphic in males; fingers of minor chela (Fig. 41 B) subcircular in cross-section, gently tapering to tip, scissor-like, cutting margins with few sharp teeth. Ventral surface of cheliped merus of both sexes with 4 large teeth (sometimes 3 plus additional small tooth or large tubercle) on outer margin, large round tooth or tubercle near anterior portion of inner margin (Fig. 42 H). Inner margin of carpi with long distal tooth (Fig. 11 A–C). Inner margin of basis-ischium of adult major cheliped gently granuliform (Fig. 42 H). Ambulatory legs meri unarmed except with short granules along margins. Ambulatory legs (Fig. 11 B, C) proportionally long, folded P5 reaching beyond front. P5 dactylus straight (Figs. 11 B; 101A‒D), merus 0.9 cl. Fused thoracic sternites 1, 2 (Fig. 52 D) transversely short, narrow; fused thoracic sternites 3, 4 (Fig. 52 D; 91B) transversely narrow. Male pleon (Figs. 52 D; 59D) lateral margins of somite 6, fused somites 3‒5 nearly straight; postero-lateral regions slightly swollen; telson proportionally short. 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, quadrate; “supplementary plate” long, subrectangular; structures tightly appressed with most of penis concealed (e.g., Fig. 59 D). G1 (Fig. 73 A‒D) stout, distal segment straight, distal segment strongly curved outwards, with spinules, often extending outside closed pleon, tuft of setae just before tip. G2 (Fig. 73 E) about half G1, curved, slender, slightly distended, proportionally long distal segment. Somites of female pleon (Fig. 87 B) with convex lateral margins; telson proportionally short. Sterno-pleonal cavity of female (Fig. 91 B) deep, vulvae relatively close together, located on outer margins of cavity close to suture 5/6.
Colour. Individuals are covered with dark brown detritus when freshly collected (Fig. 101 A, B). The carapace and pereiopods of live individuals are white when the detritus is cleaned off (Fig. 101 C, D), with the eyes iridescent like a tapetum lucidum, which in vertebrates reflects light and causes the eyes to shine (Fig. 101 A, B).
Remarks. Angustopelta aurita is very distinctive in that the anterolateral margin is always armed with a prominent tooth in all the specimens examined from Philippines, all of which are adult and relatively large. The presence of anterolateral teeth nevertheless appears to be related not only to sex but to size as well. Four of the five females from the Kai and Taminbar Is., Indonesia (all relatively small) lacked any teeth or tubercles on the sides of the carapace, as in the case of some specimens of Angustopeleta robusta n. sp. Only one of the five females, the largest of the five (11.7 × 12.9 mm, MNHN-IU-2013-9086) had distinct teeth.
The G1 structure varies with size. The G1 of smaller specimens is less strongly curved (Fig.73 A) compared to large males, which is prominently so (Fig. 73 B). The outer margin of the basal segment is also sinuous in smaller specimens (Fig. 73 A) but more evenly convex in larger ones (Fig. 73 B). The G1 structure of adult males is characteristic in the stoutness of the basal and distal parts, and in the distal part being prominently curved (Fig. 73 B). In the degree of curvature, the G1 of A. aurita closely resembles that of A. modesta n. sp. (Fig. 74 F‒H), except that the basal and distal parts are more slender in the latter species. The ambulatory legs of A. aurita (Fig. 11 A, B) are proportionately as long as those of A. modesta n. sp. (Fig. 12 C‒G), and longer than those of A. cribrorum and A. robusta n. sp. (Figs. 11 D, E; 12A, B) (see remarks for other species below).
Distribution. Western Pacific Ocean (Japan to Indonesia). Depth: 271‒1775 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 56-57, DOI: 10.11646/zootaxa.4209.1.1, http://zenodo.org/record/272646