Chinommatia bicuspida 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
Chinommatia
Chinommatia bicuspida

description: Chinommatia bicuspida n. sp.
(Fig. 15 B‒D; 25B; 32D; 43E‒G; 44C, D, G, H; 53D; 60C; 75J‒M)
Type material. Holotype female (10.7 × 12.9 mm) (MNHN-IU-2011-0954), Papua New Guinea, Gulf of Huon, Southeast Point, BIOPAPUA, stn CP3629, 06°57’S, 147°08’E, 240–269 m, 22.08.2010.
Paratypes: 1 paratype female (16.7 × 20.4 mm) (MNHN-IU-2014-17791), Papua New Guinea, Open Bay, stn CP3664, 04°50’S, 151°38’E, 195–340 m, 23.09.2010; 1 paratype female (9.9 × 12.1 mm) (ZRC 2015.235, ex MNHN-IU-2011-1523), BIOPAPUA, Southeast Point, Gulf of Huon, stn CP3630, 06°54’S, 147°03’E, 305–307 m, 22.10.2010.
Other material examined. Fiji. MUSORSTOM 10: 2 males (7.6 × 9.8 mm, 10.6 × 12.7 mm), 2 females (6.6 × 7.9 mm, 6.2 × 7.6 mm) (ZRC 2015.236, ex MNHN-IU-2013-9056), Bligh Water, stn CP1320, 17°16.8’S, 177°53.6’E, 290–300 m, 06.08.1998; 2 males, 1 female (MNHN-IU-2013-9029), Bligh Water, stn CP1322, 17°17’S, 177°48’E, 210–282 m, 07.08.1998; 1 female (MNHN-IU-2013-9059), Bligh Water, stn CP1325, 17°16’S, 177°50’E, 282–322 m, 07.08.1998; 2 females (MNHN-IU-2013-9035), Bligh Water, stn CP1328, 17°17’S, 177°50’E, 248–277 m, 07.08.1998; 2 males (MNHN-IU-2013-9030), south of Viti Levu, stn CP1363, 18°12’S, 178°33’E, 144–150 m, 15.08.1998; 2 males, 4 females (MNHN-IU-2013-9025), south of Viti Levu, stn CP1366, 18°12’S, 178°33’E, 149–168 m, 15.08.1998; 1 female (MNHN-IU-2013-9027), no data; 4 females (MNHN-IU- 2013-9026), south of Viti Levu, stn CP1370, 18°12’S, 178°33’E, 230–251 m, 18.08.1998; 1 male (MNHN-IU- 2013-9057), south of Viti Levu, stn DW1383, 18°18’S, 178°03’E, 144–150 m, 15.08.1998.— BORDAU 1: 1 female (5.8 × 6.7 mm) (MNHN-IU-2013-9468), Natawa Bay, stn CP1403, 16°40’S, 179°36’E, 220–224 m, 25.02.1999; 1 female (MNHN-IU-2013-9034), Natawa Bay, stn CP1403, 16°40’S, 179°36’E, 220–224 m, 25.02.1999; 1 female (MNHN-IU-2013-9036), Lau, Natawa Bay, stn CP1405, 16°39’S, 179°36’E, 180 m, 25.02.1999.
Diagnosis. Carapace (Fig. 15 B‒D) subtrapezoidal, convex, 1.1‒1.2 wider than long; front bilobed, with shallow median cleft; anterolateral margins arcuate, minutely granular with granules higher along lateral margins, without distinct lobes or teeth. Eye peduncle (Fig. 25 B) filling orbit, short, mobile; cornea reduced, with reduced pigmentation. Epistome (Fig. 25 B) with semicircular median lobe with deep median fissure, semicircular lateral margins. Third maxilliped (Fig. 32 D) merus ovate, anteroexternal angle auriculiform, ischium rectangular, about same length as merus. Proportionally long ambulatory legs (Figs. 15 B, C; 43G, H); P5 merus 0.6 cl; meri of P2, P3 usually with distinct short teeth along posterior margin, meri of other ambulatory legs usually with sharp granules (Fig. 43 G, H). Chelipeds (Figs. 15 B‒D; 43E‒G) subequal in length, slightly dissimilar in females, heteromorphic in males; fingers of minor chela (Fig. 43 F) subcircular in cross-section, scissor-like, cutting margins with distinct sharp teeth; most proximal teeth on cutting margin of major chela of males (Fig. 43 E, G) enlarged; propodus of minor cheliped of male (Fig. 44 C, D) with prominent bilobed tooth on inner margin anterior to large, hollow, flat area, opposing flattened area on ventral surface of merus. Inner margin of cheliped carpus with short tooth (Fig. 15 C, D). Fused thoracic sternites 1, 2 (Fig. 53 D) semicircular, broad, short. Male pleon (Figs. 53 D; 60C) with proportionally long telson. G1 (Fig. 75 G, K, L) stout, distal segment straight, tip slightly flared, with spinules. G2 (Fig. 75 M) about 3/4 G1 length, straight, slender, distal segment short. Female telson proportionally long. Vulvae relatively close together, located on outer margins of cavity close to suture 5/6.
Etymology. The epithet bicuspida refers to the diagnostic two-lobe tooth on the propodus of the minor cheliped of males.
Remarks. Chinommatia bicuspid a n. sp. is very close to C. cavimanus but there are several subtle but constant differences. Most notable is the structure of the large tooth present on the inner margin of the minor chela, anterior to the large hollowed out and flattened area opposing the flattened area on the ventral surface of merus when the cheliped is flexed. In C. cavimanus, this tooth is relatively higher, more swollen, with the distal part partially dilated with a weakly or indistinctly bilobed structure (Fig. 44 A, B). In C. bicuspid a n. sp., this tooth is distinctly lower but the distal part is more prominently bilobed (Fig. 44 C, D). The G1 structures are also distinct. In C. bicuspid a n. sp., the G1 is relatively more slender, with the structure gently curved and the distal opening is larger (Fig. 75 J‒L), whereas in C. cavimanus the G1 is somewhat stouter and more prominently curved with the distal opening relatively smaller (Fig. 75 A‒C). This difference in G1 structure, while subtle, is constant. The ventral margins of the first and second ambulatory meri of C. bicuspid a n. sp. are generally more prominently spinose (Fig. 44 G, H), notably in larger specimens; with that of C. cavimanus generally weaker (Fig. 44 E, F). There is nevertheless a variation and whereas most specimens of C. cavimanus have relatively weakly spinose ventral meral margins, they are sometimes strong. Their distributions also differ, with C. cavimanus present from Philippines to central Indonesia, whereas C. bicuspida n. sp. is so far known from Papua New Guinea and Fiji.
Distribution. Western Pacific Ocean (Papua New Guinea and Fiji). Depth: 144‒ 322 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 65-66, DOI: 10.11646/zootaxa.4209.1.1, http://zenodo.org/record/272646