Carcinoplax cracens, Castro, 2007
Castro, Peter, 2007, A reappraisal of the family Goneplacidae MacLeay, 1838 (Crustacea, Decapoda, Brachyura) and revision of the subfamily Goneplacinae, with the description of 10 new genera and 18 new species, Zoosystema 29 (4), pp. 609-774 : 630-633
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TYPE MATERIAL. — SMIB 5, stn DW 94, ♂ holotype, cl 18.9 mm, cw 25.6 mm ( MNHN-B 29430 ) ; preadult ♀ paratype, cl 7.0 mm, cw 11.2 mm ( MNHN-B 29816 ). — Panglao I., tangle nets of local fishermen, 100-300 m, ♂ paratype, cl 13.5 mm, cw 19.4 mm ( MNHN-B 29721 ) ; 3 ♀♀ paratypes (cl 15.2 mm, cw 21.3 mm; cl 15.0 mm, cw 10.8 mm; cl 18.4 mm, cw 25.0 mm) ( MNHN-B 29721 ) .
TYPE LOCALITY. — New Caledonia, off southeastern coast, 22°19.6’S, 168°42.8’E, 275 m.
MATERIAL EXAMINED. — Taiwan. TAIWAN 2000, stn DW 5, 22°40.5’N, 119°56.5’E, 213-236 m, 27.VII.2000, 1 ♀ ( MMBA).
Philippine Islands. Bohol, Balicasag I., off Panglao I., tangle nets of local fishermen of local fishermen, 50-500 m, 28.XI.2001, 2 ♂♂ ( ZRC 2001.0527). — 200-300 m, VI.2002, 8 ♂♂, 2 ♀♀, 3 ovig. ♀♀ ( ZRC 2002.0653), 3 ♂♂, 1 ♀ ( ZRC 2002.0649). — 50-500 m, III.2004, 2 ♂♂ ( ZRC 2004.0767). — V.2004, 1 ♀ ( ZRC 2004.0768). — Panglao I., Maribohoc Bay, tangle nets of local fishermen, 100-300 m, T. J. Arbasto coll., XI.2003 - IV.2004, 1 ♂, 3 ♀♀ ( MNHN-B 29721). — Panglao I., north coast, tangle nets of local fishermen, T. J. Arbasto coll., VII.2004 - V.2005, 1 ♂ parasitised by sacculinid ( ZRC 2006.0218).
? Indonesia. Kai Is, KARUBAR, stn DW 49, 07°59’S, 132°58’E, 209- 206 m, 29.X.1991, 1 pre-adult ♀ ( MNHN- B 30056).
Solomon Islands. SALOMON 2, stn DW 2255, 08°07.7’S, 157°02.1’E, 185-196 m, 3.XI.2004, 1 ♂, 1 pre-adult ♂ ( MNHN-B 30465).
New Caledonia. SMIB 5, stn DW 94, 22°19.6’S, 168°42.8’E, 275 m, 13.IX.1989, ♂ holotype ( MNHN-B 29430 ) GoogleMaps ; 1 pre-adult ♀ paratype ( MNHN-B 29816 ) .
ETYMOLOGY. — From cracens, Latin for “slender” and “graceful”, in reference to the long and slender ambulatory legs (P2-P5) diagnostic of the species.
DISTRIBUTION. — Western Pacific Ocean from Taiwan ( Ho et al. 2004, as C. inaequalis ) to New Caledonia. Depth: 50- 500 m.
Carapace ( Fig. 3 View FIG ; Ho et al. 2004: fig. 6G, as Carcinoplax inaequalis ) quadrate, slightly wider than long (1.3 as wide as long in holotype), anterolateral borders arched. Carapace convex, with 2 conspicuous, raised horizontal regions extending to lateral borders, anterior one across gastric region, posterior one across cardiac region; 2 spherical, slightly raised regions in central gastric portion of wide groove formed between horizontal ridges. Dorsal surface of carapace granular along anterior (hepatic region) and posterolateral borders; granules conspicuous along posterolateral borders. Front lamellar, straight, margin slightly convex, not marked by median notch. Slight notch between front, inner edge of supraorbital border. Supraorbital borders sinuous, margins smooth. Suborbital borders with large granules, each border with blunt inner tooth not visible dorsally. Large blunt to slightly pointed tooth on outer orbital angle; 2 anterolateral teeth on each side of carapace, first blunt, second curved, acute-tipped. Posterolateral borders arched.
Subhepatic, pterygostomial regions, pterygostomial crest, pterygostomial lobe, merus, ischium of third maxilliped endopod with short, conspicuous granules.
Eye peduncles ( Fig. 3 View FIG ) short (0.2 front width), distal margin slightly granular, cornea slightly expanded distally.
Chelipeds (P1) nearly equal in males, females, slightly more slender in males; fingers slender, as long as propodus, with cutting edges and broadly
blunt teeth, more than half of distal portion of fingers dark brown. Broad, curved, acute- to obtuse-tipped tooth on inner (ventral), proximal margin of carpus; smaller, curved, acute-tipped tooth on outer (dorsal), distal margin. Ambulatory legs (P2-P5) conspicuously long, slender, smooth; many short simple setae along inner, outer margins of P5 propodus, dactylus, outer margin of P5 carpus; P5 dactylus long, slender, smooth; length of P5 merus 0.6 cl.
Male abdomen narrowly triangular, with 6 freelymovable somites plus telson; telson slightly wider than long, somite 3 covers space between P5 coxae. Somites 1, 2 slightly narrower than somite 3, thoracic sternite 8 not visible. G1 ( Fig. 2A View FIG ) long, slender; straight, slightly pointed tip. G2 ( Fig. 2B View FIG ) slender, nearly equal or slightly longer than G1, slightly curved flagellum, tip with spinule at each side.
Female abdomen wide. Telson slightly wider than long. Somites 1, 2 cover space between P5 coxae, thoracic sternite 8 not visible. Vulva of mature females greatly expanded, extending from edge of slightly deflected suture 5/6 to suture 6/7; membrane covers aperture leaving space open along pointed anterior margin.
Carapace and chelipeds of recently preserved specimens with thick orange-red bands on a white to light orange-red background; ambulatory legs banded orange-red (see Ho et al. 2004: fig. 6G, as Carcinoplax inaequalis ).
The examination of part of the type material of C. inaequalis ( Yokoya, 1933) (see Remarks of the species below) showed that the Taiwan material identified as belonging to C. inaequalis species by Ho et al. (2004) as well as additional material from the Philippine Is and New Caledonia actually belong to a previously undescribed species.
The new species shares many characters with C. inaequalis and C. specularis Rathbun, 1914 : similar G1 and G2; conspicuous, rounded outer orbital angle; and acute second anterolateral tooth. The walking legs are noticeably longer and more slender in C. cracens n. sp. ( Fig. 3 View FIG ) than in both C. inaequalis and C. specularis . The distal end of the merus of the folded P5 extends well beyond the tip of the second anterolateral tooth, but they extend to just the tip of the tooth in the other two species. The second anterolateral tooth is blunt in C. cracens n. sp. but acute in C. inaequalis and C. specularis . Also characteristic of the new species are the two conspicuous, carina-like horizontal ridges that extend across the carapace along the hepatic and gastric regions. Although not that conspicuous, the ridges may also be observed in C. inaequalis and in large specimens of C. specularis . The low tubercles on the hepatic region of the carapace are larger and hence more conspicuous in C. cracens n. sp. than in the other two species.
A small (cl 5.2 mm, cw 6.3 mm), incomplete specimen (P1 and P2-P4 on one side only) from the Kai Is, Indonesia ( MNHN-B 30056) is questionably identified as belonging to the new species.
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