Chinommatia bicuspida, Ng, Peter K. L. & Castro, Peter, 2016

Ng, Peter K. L. & Castro, Peter, 2016, Revision of the family Chasmocarcinidae Serène, 1964 (Crustacea, Brachyura, Goneplacoidea), Zootaxa 4209 (1), pp. 1-182: 65-66

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Chinommatia bicuspida

n. sp.

Chinommatia bicuspida   n. sp.

( Fig. 15 View FIGURE 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 GoogleMaps   .

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 GoogleMaps   ; 1 paratype female (9.9 × 12.1 mm) ( ZRC 2015.235 View Materials , 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 GoogleMaps   .

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 View Materials , ex MNHN-IU-2013-9056), Bligh Water , stn CP1320, 17°16.8’S, 177°53.6’E, 290–300 m, 06.08.1998 GoogleMaps   ; 2 males, 1 female (MNHN-IU-2013-9029), Bligh Water , stn CP1322, 17°17’S, 177°48’E, 210–282 m, 07.08.1998 GoogleMaps   ; 1 female (MNHN-IU-2013-9059), Bligh Water , stn CP1325, 17°16’S, 177°50’E, 282–322 m, 07.08.1998 GoogleMaps   ; 2 females (MNHN-IU-2013-9035), Bligh Water , stn CP1328, 17°17’S, 177°50’E, 248–277 m, 07.08.1998 GoogleMaps   ; 2 males (MNHN-IU-2013-9030), south of Viti Levu, stn CP1363, 18°12’S, 178°33’E, 144–150 m, 15.08.1998 GoogleMaps   ; 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 GoogleMaps   ; 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 GoogleMaps   ; 1 male (MNHN-IU- 2013-9057), south of Viti Levu, stn DW1383, 18°18’S, 178°03’E, 144–150 m, 15.08.1998 GoogleMaps   .— 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 GoogleMaps   ; 1 female (MNHN-IU-2013-9034), Natawa Bay , stn CP1403, 16°40’S, 179°36’E, 220–224 m, 25.02.1999 GoogleMaps   ; 1 female (MNHN-IU-2013-9036), Lau , Natawa Bay, stn CP1405, 16°39’S, 179°36’E, 180 m, 25.02.1999 GoogleMaps   .

Diagnosis. Carapace ( Fig. 15 View FIGURE 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 View FIGURE 25 B) filling orbit, short, mobile; cornea reduced, with reduced pigmentation. Epistome ( Fig. 25 View FIGURE 25 B) with semicircular median lobe with deep median fissure, semicircular lateral margins. Third maxilliped ( Fig. 32 View FIGURE 32 D) merus ovate, anteroexternal angle auriculiform, ischium rectangular, about same length as merus. Proportionally long ambulatory legs ( Figs. 15 View FIGURE 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 View FIGURE 43 G, H). Chelipeds ( Figs. 15 View FIGURE 15 B‒D; 43E‒G) subequal in length, slightly dissimilar in females, heteromorphic in males; fingers of minor   chela ( Fig. 43 View FIGURE 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 View FIGURE 43 E, G) enlarged; propodus of minor   cheliped of male ( Fig. 44 View FIGURE 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 View FIGURE 15 C, D). Fused thoracic sternites 1, 2 ( Fig. 53 View FIGURE 53 D) semicircular, broad, short. Male pleon ( Figs. 53 View FIGURE 53 D; 60C) with proportionally long telson. G1 ( Fig. 75 View FIGURE 75 G, K, L) stout, distal segment straight, tip slightly flared, with spinules. G2 ( Fig. 75 View FIGURE 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 View FIGURE 44 A, B). In C. bicuspid   a n. sp., this tooth is distinctly lower but the distal part is more prominently bilobed ( Fig. 44 View FIGURE 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 View FIGURE 75 J‒L), whereas in C. cavimanus   the G1 is somewhat stouter and more prominently curved with the distal opening relatively smaller ( Fig. 75 View FIGURE 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 View FIGURE 44 G, H), notably in larger specimens; with that of C. cavimanus   generally weaker ( Fig. 44 View FIGURE 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.


Zoological Reference Collection, National University of Singapore