Carcinoplax velutina, 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 : 652-654

Carcinoplax velutina n. sp.

( Figs 9 ; 10 )

Carcinoplax aff. verdensis – Poupin 1996a: 98 [in list]; 1996b: pl. 16, fig. d [ French Polynesia].

TYPE MATERIAL. — SMSRB collections, stn 397, ♂ holotype, cl 11.4 mm, cw 14.7 mm ( MNHN-B 29826 ) ; ♂ paratype, cl 11.3 mm, cw 14.3 mm ( MNHN-B 20794 ) ; ♀ paratype, cl 9.7 mm, cw 12.5 mm ( MNHN-B 29828 ) .

TYPE LOCALITY. — French Polynesia,Tuamotu Archipelago, Moruroa atoll, 21°53.3’N, 138°51.6’E, 680 m.

MATERIAL EXAMINED. — Vanuatu. BOA1, unknown station, 1 ♂ ( MNHN-B 30450).

Fiji. MUSORSTOM 10, stn CP 1344, 16°45.3’S, 177°40.5’E, 588-610 m, 10.VIII.1998, 1 ♂ ( MNHN-B 29835).

BORDAU 1, stn CP 1392, 16°49’S, 179°54’E, 545- 651 m, 23.II.1999, 1 ♂ ( MNHN-B 29834).

French Polynesia. Society Is, Bora Bora, 16°28’S, 151°47’W, trap, 450-600 m, 23.VII.1988, SMSRB collections, J. Poupin coll., 1 ♂ ( MNHN-B 20904).

Tuamotu Archipelago, Moruroa atoll, 21°51’S, 138°47’W, trap, 570-670 m, 29.XI.1988, SMSRB collections, J. Poupin coll., ♂ paratype ( MNHN-B 20794). — Hao I., 18°04.2’S, 141°01.8’W, trap, 500 m, 2.VI.1990, ♀ paratype ( MNHN-B 29828). — Moruroa atoll, stn 383, 21°46.2’S, 138°54.0’W, trap, 600 m, 9.III.1991, 1 ♂ ( MNHN-B 29827). — Moruroa atoll, stn 397, 21°53.3’N, 138°51.6’E, trap, 680 m, 17.III.1991, ♂ holotype ( MNHN-B 29826).

ETYMOLOGY. — From velutinus, derived from villus, Latin for “shaggy hair”, in reference to the short tomentum on the ambulatory legs (P2-P5) and ventral surface of the carapace and abdomen, giving them, particularly the legs, a velvety appearance.

DISTRIBUTION. — Vanuatu, Fiji, and French Polynesia. Depth: 300- 680 m.

DESCRIPTION

Carapace ( Figs 9A ; 10 ; Poupin 1996b: pl. 16, fig. d, as Carcinoplax aff. verdensis ) quadrate, slightly wider than long (1.3 as wide as long in holotype). Carapace slightly convex, granular along anterior, lateral borders, with short setae on posterior half, without clear indication of regions.Front lamellar, margin granular, straight, not marked by median notch. Notch between front, inner edge of supraorbital border. Supraorbital borders sinuous, margins granular, slight prominence before outer orbital angle.Suborbital borders granular, each with short, blunt inner tooth not visible dorsally. Outer orbital angle with flat, granular, blunt tooth; 2 dorso-ventrally flat, triangular, granular, blunttipped anterolateral teeth on each side of carapace, margin between anterolateral teeth nearly straight. Posterolateral borders arched.

Subhepatic, pterygostomial regions, pterygostomial lobe, merus, ischium of third maxilliped endopod with short, conspicuous granules. Margins of thoracic sternum with short setae.

Eye peduncles ( Figs 9A ; 10 ) short (0.2 front width), distal margin granular, cornea short, not expanded distally.

Chelipeds (P1) ( Fig. 10 ; Poupin 1996b: pl. 16, fig. d, as Carcinoplax aff. verdensis ) nearly equal in males, females, slightly more slender in females; fingers slender, as long as propodus in males, slightly longer than propodus in females, with blunt teeth, 3/4 or nearly all distal portion of fingers dark brown. Broad tooth on inner (ventral), proximal margin of carpus, acute-tipped in some specimens, inner margin granular in holotype. Ambulatory legs (P2- P5) long (distal end of the merus of the folded P5 reaches well beyond tip of second anterolateral tooth, in holotype almost reaching tip of first anterolateral tooth), relatively stout articles, granular, many short and long simple setae along inner, outer margins of articles; P5 dactylus long, slender, setose; length of P5 merus 0.7-0.8 cl.

Male abdomen ( Fig. 9B ) broadly triangular, fringed by short setae, with 6 freely-movable somites plus telson; telson slightly wider than long. Somite 3 covers space between P5 coxae; somites 1, 2 only slightly narrower than somite 3, thoracic sternite 8 not visible. G1 ( Fig. 9C ) long, slender, straight; pointed tip. G2 ( Fig. 9D ) slender, slightly longer than G1, slightly curved flagellum, tip with 2 terminal spinules.

Female abdomen narrow, fringed with many long setae. Telson 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.

COLOUR

Carapace light orange; chelipeds (P1) mostly light orange, tips of fingers dark brown ( Poupin 1996b: pl. 16, fig. d, as Carcinoplax aff. verdensis ).

REMARKS

Carcinoplax velutina n. sp. is easily separated from other species of Carcinoplax by its long ambulatory legs (P2-P5), the distal end of the merus of the P5 reaching the second anterolateral tooth; the short tomentum on the legs and on the margins of the abdomen (longer setae on the female abdomen) and thoracic sternum; the short setae on the posterior half of the carapace; and the nearly flat outer orbital teeth.

It is particularly close to C. tuberosa n. sp. Similarities and differences between the two species are discussed in the description of the latter (see above). There are also some similarities with C. abyssicola , described from Fiji, and C. specularis , with a wider geographical distribution but also known from Fiji, which have a short tomentum on the carapace and

Castro P.

ambulatory legs and the legs have relatively stout articles. In C. abyssicola , however, the outer orbital tooth is greatly reduced so that the carapace margin beyond the orbit is typically slanted, not straight, and the anterolateral teeth are curved and more salient than in C. velutina n. sp. (see Guinot 1989: fig. 38, pl. 9, figs A, B) and the eyes are clearly larger than in C. velutina n. sp., where the cornea is not much enlarged distally.

Carcinoplax velutina n. sp. somewhat resembles C. longipes from the Indian Ocean and the Philippine Is in the shape of the outer orbital tooth and in the long ambulatory legs. C. longipes , however, has a curved first anterolateral tooth ( Guinot 1989: fig. 26, pl. 10, figs A, B; fig. 27, pl. 10, figs D, E, as Carcinoplax aff. longipes ; pl. 10, fig. G, as Carcinoplax sp.) and a much sparse tomentum on the carapace and ambulatory legs.

A small male from Fiji (cl 8.0 mm, cw 10.1 mm; MNHN-B 29834) had the same carapace shape and anterolateral teeth and the same relative length of the ambulatory legs as in C. velutina n. sp. but the setae of the ambulatory legs (P2-P5) were longer and more conspicuous than in C. tuberosa n. sp.

Figures

FIG. 9. — Carcinoplax velutina n. sp., ♂ holotype, cl 11.4 mm, cw 14.7 mm, Moruroa atoll, French Polynesia, SMSRB collections, stn 397, 680 m (MNHN-B 29826): A, dorsal surface of the carapace; B, abdomen; C, left G1, dorsal view; D, left G2, ventral view. Scale bars: A, 5 mm; B, 3 mm; C, D, 1 mm.

FIG. 10. — Carcinoplax velutina n. sp., ♂ holotype, cl 11.4 mm, cw 14.7 mm, Moruroa atoll, French Polynesia, SMSRB collections, stn 397, 680 m (MNHN-B 29826).