Thyraplax crosnieri (Guinot & Richer de Forges, 1981) 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 : 674-676

Thyraplax crosnieri (Guinot & Richer de Forges, 1981) n. comb.

( Figs 13C ; 19 )

Carcinoplax crosnieri Guinot & Richer de Forges, 1981a: 1113, 1115 , pl. 6, figs 4, 4a, 4b (nomen nudum).

Carcinoplax crosnieri Guinot & Richer de Forges, 1981b: 251 : figs 9A, B, 10I-L, pl. 6, figs 4, 4a, 4b [Loyalty Is]. — Guinot 1989: 314 [in list], fig. 43, pl. 13, fig. G [Loyalty Is]. — Ikeda 1998: 15, 43, 137, pl. 57 [ Japan]. — Takeda et al. 2006: 204 [in list] [ Japan].

TYPE MATERIAL. — ♂ holotype, cl 31.8 mm, cw 38.1 mm ( MNHN-B 6834).

TYPE LOCALITY. — Loyalty Islands, between Jouan Reef and Ouvéa, 20°40.2’S, 166°58.5’E, trap, 400 m.

MATERIAL EXAMINED. — Philippine Islands. Bohol, Balicasag I., off Panglao I., tangle nets of local fishermen, 50-500 m, 28.XI.2001, 1 ♂, 2 ♀♀ ( ZRC 2004.0718). — 200-300 m, VI.2002, 2 ♂♂ ( ZRC 2002.0652). — 25- 30.VII.2003, 1 ♂ ( ZRC 2004.0719). — XII.2003, 1 ♂ ( ZRC 2004.0779). — 50-500 m, 2.III.2004, 1 ♂, 1 ♀ ( ZRC 2004.0720).

PANGLAO 2004, stn P4, tangle nets of local fishermen, 31.V.2004, 1 ♂ ( ZRC 2006.0177 ) ; 1 ♂, 1 ♀ ( ZRC 2006.0181 ) .

PANGLAO 2005, stn CP 2359, Bohol / Sulu seas sill, 08°49.9’N, 123°34.9’E, 437-476 m, 26.V.2005, 2 ♂♂, 2 ♀♀, 1 pre-adult ♀ (ZRC 2006.0199). — Stn CP 2362, Bohol / Sulu seas sill, 08°56.5’N, 123°32.7’E, 679-740 m, 26.V.2005, 2 ♀♀ (ZRC).

Solomon Islands. SALOMON 1, stn DW 1788, 09°19.4’S, 160°15.4’E, 341-343 m, 30.IX.2001, 1 ♂ ( MNHN-B 29399).

New Caledonia. BIOCAL, stn CP 45, 22°47’S, 167°15’E, 430-465 m, 30.VIII.1985, 1 ♀ ( MNHN-B 29544).

MUSORSTOM 4, stn DW 222, 22°57.6’S, 167°33.0’E, 410-440 m, 30.IX.1985, 1 ♀ ( MNHN-B 29422).

BIOGEOGAL, stn DW 291, 20°34.47’S, 166°54.33’E, 800 m, 24.VII.1987, 1 ♀ ( MNHN-B 29471).

BATHUS 4, stn DW 929, 18°51.55’S, 163°23.27’E, 502-516 m, 7.VIII.1994, 1 ♀ ( MNHN-B 29416).

NORFOLK 2, stn DW 2053, 23°40’S, 168°16’E, 670-708 m, 24.X.2003, 1 pre-adult ♀ ( MNHN-B 29766). — Stn DW 2081, 25°54’S, 168°22’E, 500-505 m, 28.X.2003, 1 ♀ ( MNHN-B 29787).

Loyalty Islands. Between Jouan Reef and Ouvéa, 20°40.2’S, 166°58.5’E, trap, 400 m., 3.III.1977, ♂ holotype ( MNHN-B 6834).

DISTRIBUTION. — Loyalty Is ( Guinot & Richer de Forges 1981b) and now from the Philippine Is, Solomon Is, and New Caledonia. Depth: 341- 800 m. Specimens were also obtained from tangle nets of local fishermen in the Philippines that obtained material from estimated depths of 50- 500 m.

COLOUR

Photographs of freshly collected material from the Philippine Is (PANGLAO 2005) showed an orange carapace. Recently-preserved material also from the Philippine Is had irregular, thin, bright-orange lines and irregular spots on the carapace, chelipeds,

Revision of Goneplacinae ( Crustacea, Brachyura)

and the meri of the ambulatory legs. The specimen from Japan shown by Ikeda (1998), however, is mostly orange.

REMARKS

The large size of the male holotype (cl 31.8 mm, cw 38.1 mm, MNHN-B 6834), which was collected from traps, exhibits some important differences from the rest of the material available for examination, which was dredged. The additional material includes eight much smaller males varying from cl 13.9 mm, cw 18.1 mm ( New Caledonia, MNHN-B 29399) to cl 21.4 mm, cw 27.0 mm (Philippine Is, ZRC 2004.0720). The tooth-like tubercles at the base of the telson of the holotype ( Guinot & Richer de Forges 1981b: 252) are obsolete or much smaller and obtuse in smaller males. More significant are differences in the G1 and G2. The distal portion of the G1 of the holotype ( Guinot & Richer de Forges 1981b: fig. 10I-K) is thicker, straighter, and provided with more denticles and the basal portion slightly wider than in the smaller males, where the distal third is bent outwardly. A short row of plumose setae was found on the outer margin of the base of the distal portion in a small male (cl 16.5 mm, cw 21.5 mm, ZRC 2004.0720). The G1 is nearly straight, however, in a medium size individual (cl 12.5 mm, cw 15.7 mm; ZRC 2006.0199).The G2 of the holotype is similarly straighter than in the smaller males.These differences appear to be due to size rather than species-specific. The examination of the G1 and G2 of specimens that are intermediate in size between the males examined here and the holotype should confirm or reject this assumption.

The vulva of small females is oval, extending from suture 5/6 to suture 6/7, and partially covered with a triangular vulvar cover on the postero-lateral margin. In larger females ( Fig. 19 ) the vulva is crescent-shaped and the vulvar cover is thicker and larger than in small females. The vulvar cover overhangs the vulva to almost reach the inner margin, thus creating two apertures, an anterior and a posterior one.

Thyraplax crosnieri n. comb. is close to T. cooki ( Rathbun, 1906) n. comb. Differences between the two species are outlined in the Remarks section for the latter (see below); differences between all five species of Thyraplax n. gen. are summarized in Table 3.

Figures

FIG. 13. — A, Pycnoplax surugensis (Rathbun,1932) n. comb., ♂, cl 14.7 mm, cw 20.6 mm,off southern coast of New Caledonia,BATHUS 2, stn DW 719,22°47.57’S,167°14.58’E,444-455 m (MNHN-B 29412);B, Pycnoplax bispinosa (Rathbun, 1914) n. comb., ♀, cl 9.0 mm, cw 11.2 mm,off Rendova I., SALOMON 2,stn CP 2287,253-255 m (MNHN-B 30088);C, Thyraplax crosnieri (Guinot & Richer de Forges, 1981) n. comb., ♀, cl 10.6 mm, cw 13.5 mm, off southern coast of New Caledonia, MUSORSTOM 4, stn DW 222, 410-440 m (MNHN-B 29422).

FIG. 19. — Thyraplax crosnieri (Guinot & Richer de Forges, 1981) n. comb., ♀, cl 16.7 mm, cw 21.9 mm, Balicasag I., off Panglao I., Philippine Is, 50-500 m (ZRC 2004.0720), thoracic sternum, vulva, and vulvar cover.