Carcinoplax tuberosa, 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 : 648-650
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TYPE MATERIAL. — VOLSMAR, stn DW 5, ♂ holotype, cl 6.9 mm, cw 8.8 mm ( MNHN-B 29829 ) ; ♂ paratype, cl 7.0 mm, cw 9.0 mm; ♀ paratype, cl 6.8 mm, cw 8.8 mm; ovig. ♀ paratype, cl 6.9 mm, cw 8.8 mm, same as holotype ( MNHN-B 29833 ). — MUSORSTOM 8, stn CP 1136, ♀ paratype, cl 5.8 mm, cw 6.8 mm, ( MNHN-B 29830 ) .
TYPE LOCALITY. — New Hebrides Ridge, Matthew and Hunter islands, 22°25.9’S, 171°46.5’E, 700 m.
MATERIAL EXAMINED. —? Philippine Islands. Bohol, Balicasag I., off Panglao I., PANGLAO 2004, stn B39, Panglao I., Pontod Lagoon, 09°32.80’N, 123°42.10’E, 17-25 m, reef wall with small caves, 2.VII.2004, 1 preadult ♂ ( ZRC 2006.0172).
Vanuatu. MUSORSTOM 8, stn CP 1136, 15°40’S, 167°01’E, 398-400 m, 11.X.1994, ♀ paratype ( MNHN-B 29830).
Matthew and Hunter islands. VOLSMAR, stn DW 5, 22°25.9’S, 171°46.5’E, 700 m, 1.VI.1989, ♂ holotype ( MNHN-B 29829), ♂ paratype, ♀ paratype, ovig. ♀ paratype ( MNHN-B 29833).
ETYMOLOGY. — From tuber, Latin for “swelling” or “bulb”, in reference to the conspicuous tubercle-like granules on the outer and dorsal surface of the chelipeds (P1) that is diagnostic to the species.
DISTRIBUTION. — Southwestern Pacific Ocean: Vanuatu and the Matthew and Hunter islands south of Vanuatu, questionably from the Philippine Is. Depth: 398-400 and 700 m, questionably 17- 25 m.
Carapace ( Figs 6A View FIG ; 7 View FIG ) quadrate, slightly wider than long (1.3 as wide as long in holotype). Carapace slightly convex, slightly granular along anterior, lateral borders (conspicuously granular in ovigerous female paratype), with short setae, without clear indication of regions. Front lamellar, straight, not marked by median notch. Notch between front, inner edge of supraorbital border. Supraorbital borders sinuous, margins granular in holotype and most other specimens. Suborbital borders granular, each with short, blunt inner tooth not visible dorsally. Outer orbital angle with flat, granular, short tooth; 2 dorso-ventrally flat, triangular, granular, blunttipped anterolateral teeth on each side of carapace, margin between anterolateral teeth nearly straight. Posterolateral borders slightly arched.
Subhepatic, pterygostomial regions, merus, ischium of third maxilliped endopod with low, conspicuous granules. Margins of thoracic sternum with short setae.
Chelipeds (P1) ( Figs 7 View FIG ; 8 View FIG ) nearly equal in males, females, slightly more slender in females; fingers short, thick, about a third as long as propodus in both sexes, with blunt teeth, all or nearly all distal portion of fingers dark brown. Propodus, carpus, merus fringed with sparse, long setae (few in holotype); propodus short, thick; conspicuous, blunt or slightly acute tubercles on outer (dorsal) surface of propodus (may be only on proximal region in one of two propodi), outer (dorsal) anterior border of carpus; shorter, less conspicuous granules on inner (ventral) surface of merus, inner margin granular. Ambulatory legs (P2-P5) relatively short (distal end of merus of the folded P5 only reaches tip of second anterolateral tooth), relatively stout articles, smooth, many short and long simple setae along inner, outer margins of articles; P5 dactylus long, slender, setose; length of P5 merus 0.7 cl.
Male abdomen ( Fig. 6B View FIG ) narrowly triangular, with 6 freely-movable somites plus telson; telson 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. 6C View FIG ) long, slender, straight; rounded tip with slightly pointed inner margin. G2 ( Fig. 6D View FIG ) slender, slightly longer than G1, slightly curved flagellum, tip with 2 terminal spinules.
Female abdomen narrow, fringed with many long setae. 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 anterior margin.
Carcinoplax tuberosa n. sp. is close to C. velutina n. sp. (see description below). Both species share a short tomentum on the carapace, a more conspicuous tomentum on the ambulatory legs (P2-P5), granular ventral surface of the carapace, short and thick fingers, short eye peduncles, and cornea relatively short and not expanded distally. Carcinoplax tuberosa n. sp. is being described as a separate species on account of several differences. The G1 has a broadly rounded tip ( Fig. 6C View FIG ) whereas it is pointed in C. velutina n. sp. ( Fig. 9C View FIG ). The ambulatory legs of C. tuberosa n. sp. are shorter and slightly narrower than in C. velutina n. sp. ( Fig. 10 View FIG ). In C. tuberosa n. sp. the distal end of the merus in the folded P5 reaches the tip of the second anterolateral tooth, whereas in C. velutina n. sp. they extend well over the tooth (almost reaching the tip of the first anterolateral tooth in the holotype). The setae on the ambulatory legs of C. tuberosa n. sp. are also conspicuously longer and more numerous than in C. velutina n. sp. An exception is a pre-adult male from the Philippine Is ( ZRC 2006.0172), where the setae are short. The propodi and carpi of the chelipeds (P1) have conspicuous tubercles in C. tuberosa n. sp. ( Fig. 8 View FIG ), which are absent in C. velutina n. sp. of about the same size.
Carcinoplax tuberosa n. sp. appears to be a smallsize species, the largest male being cl 7.0 mm, cw 9.0 mm ( MNHN-B 29829) and the largest female, which was ovigerous, cl 6.9 mm, cw 8.8 mm ( MNHN-B 29833). A small female (cl 5.8 mm, cw 6.8 mm; MNHN-B 29830) had an enlarged vulva, evidence that it was mature. The damaged specimen of a pre-adult male from the Philippine Is (cl 2.5 mm, cw 2.9 mm; ZRC 2006.0172) shares all of the diagnostic characters of the type material except the long setae of its ambulatory legs. The new species thus appears not to be pre-adult specimens of C. velutina n. sp. Carcinoplax velutina n. sp., however, is known mostly from relatively large specimens (smallest: female, cl 9.7 mm, cw 12.5 mm; MNHN-B 29828).
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