Cyrtomaia polynesica, Forges, Bertrand Richer De & Ng, Peter K. L., 2008

Forges, Bertrand Richer De & Ng, Peter K. L., 2008, New records of deep­sea spider crabs of the genus Cyrtomaia Miers, 1886, from the Pacific Ocean, with description of a new species (Crustacea: Decapoda: Brachyura: Majidae), Zootaxa 1861, pp. 17-28 : 22-23

Cyrtomaia polynesica n. sp.

Fig. 1 A, B; 2A–D; 3A–C; 4A–C; 5A–D

Material examined. French Polynesia: Marquesas Is., MUSORSTOM 9, stn. CP 1307, 8°57.9’S – 140°15.8’W, 708–738 m, 10 September 1997: 1 male holotype (30.2 x 32.2 mm) (MNHN­B31237). – Tuamotu Is., Mururoa Atoll, traps, stn. 383, 21°46.2’S – 138°54.0’E, 600 m, 9 March 1991, J. Poupin coll.: 1 ovigerous female paratype (40.2 x 40.3 mm) (MNHN­B31238).

Description. Carapace covered with dense, small granules ( Fig. 1 B; 2A, B). Rostrum short, sharp. Pseudorostral spines short, pointing anteriorly. Protogastric spines longer than others, but relatively short. One strong, acute postocular teeth. One bifid, granular supraocular spine ( Figs. 1 B, 3B). Ocular peduncle short, eye round, cornea with a single tubercle basally ( Fig. 2 C). One mediogastric spine. Row of 4 or 5 large granules joining base of protogastric spine to supraocular spine. Curved ridge joining base of protogastric spine with base of postocular spine very prominent ( Fig. 2 A, B). Hepatic region with 2 short spines. Branchial region with long acute spine pointing outwards. Surface of branchial area with 2 rows of spiniform granules ( Fig. 2 A, B). Cardiac region swollen, with 2 short spines. Intestinal region with small granule. Basal antennal article with 3 sharp spines, small fourth spine ( Figs. 2 D, 3A). Second antennal article with 2 small, rounded teeth. Antennal flagellum long, with long setae ( Fig. 1 B).

Cheliped short, very spiny ( Fig.3 B, C). Merus with 4 rows of spines, longest on infra­interior border; carpus short; propodus with 5 rows of spines; fingers of chelae with internal border serrulated.

Ambulatory legs long, thin ( Fig. 1 A). P2 longest; merus long, spiny along entire length; carpus relatively long with 5 long spines on ventral border; interior border of propodus with 2 rows of long spines; dactylus curved, with 2 rows of long spines along inner border. P3 spiny along entire length. Merus markedly shorter than that of P2, with 3 rows of small spines; carpus with 2 rows of short spines; dactylus curved without spines, with long setae. P4, P5 smooth, finely granular.

Abdomen with 7 freely articulating somites, telson with distal half rounded, somites 1­6 each with one spiniform median tubercle on surface. Male first gonopod long, slender ( Fig. 5 A–D); G2 very short, without flagellum.

Remarks. Cyrtomaia polynesica n. sp., is a medium­sized species. It is included in the group of Cyrtomaia species having short pseudorostral spines, a granular carapace with the protogastric spines the longest and sharp branchial spines. In this group, allied species are: C. goodridgei McArdle, 1900 , C. intermedia Sakai, 1938 , C. guillei Guinot, 1985 , C. furici Richer de Forges & Guinot, 1988, and C. micronesica Richer de Forges & Ng, 2007.

Cyrtomaia goodridgei is rarely mentioned. It was described from Sri Lanka (= Ceylon) on the basis of material from the Investigator . Guinot (1985: 12) provided a redescription based on a small specimen having a very granular carapace, with very long protogastric spines and no supraocular spine. It is clearly very different from C. polynesica n. sp., where the carapace only has small granules, relatively short protogastric spines and possesses a supraocular spine. Cyrtomaia polynesica n. sp. differs from C. guillei , a species from Réunion, Indian Ocean, by the protogastric spines being longer and less curved than in C. guillei ; the eye has only one terminal tubercle (a crown of spines at the base of the cornea in C. guillei ), the P4 and P5 meri is smooth (granular in C. guillei ) and there is one distinct supraocular spine (only a granule in C. guillei ). Cyrtomaia polynesica n. sp. also has shorter pseudorostral spines and a less granular carapace than in C. furici , a species from New Caledonia. The supraocular spine is also much stronger and longer in C. furici than in C. polynesica n. sp. Cyrtomaia intermedia is a very rare species, described from a single specimen from Japan and never collected again. It differs from C. polynesica n. sp. by lacking a supraocular spine. The only specimen known of C. intermedia seems to be lost. It was sent by M. Takeda from the National Science Museum, Tokyo, to D. Guinot (MNHN) but the specimen never arrived in Paris. The specimen was also never returned to Tokyo (M. Takeda, pers. comm.). Guinot & Richer de Forges (1986) referred to C. intermedia two male specimens collected by traps in Guam, Micronesia, but these proved to belong to C. micronesica Richer de Forges & Ng, 2007. Cyrtomaia polynesica n. sp. and C. micronesica , its closest species, are of similar size, but there are several obvious differences. The pseudorostral spines are proportionately longer in C. polynesica n. sp. than in C. micronesica , the ambulatory legs are relatively shorter, the pseudogastric spines are much shorter, the supraocular spine is bifid (simple and triangular in C. micronesica ), the intestinal area only has a very small granule (a large granule in C. micronesica ), and there are four very long and sharp spines on the basal antennal article (three in C. micronesica ).

The female paratype of C. polynesica n. sp. ( Fig. 4 A–C) is relatively less granular than the male, with spines shorter. The supraocular spines are not bifid and the hepatic region has a short spine, not two as in the male. It is ovigerous with numerous small eggs.

Figures

FIGURE 1. Cyrtomaia polynesica n. sp. Male holotype (30.2 x 32.2 mm) (MNHN­B 31237). A, overall dorsal view; B, dorsal view of carapace.

FIGURE 2. Cyrtomaia polynesica n. sp. Male holotype (30.2 x 32.2 mm) (MNHN­B 31237). A, right lateral view of carapace; B, left lateral view of carapace; C, frontal view of carapace; D, ventral view of buccal frame.

FIGURE 3. Cyrtomaia polynesica n. sp .. Male holotype (30.2 x 32.2 mm) (MNHN­B 31237). A, ventral view; B, left cheliped in dorsal view; C, left cheliped in ventral view.

FIGURE 4. Cyrtomaia polynesica n. sp.. Female paratype (40.2 x 40.3 mm) (MNHN­B 31237). A, overall dorsal view. B, dorsal view of carapace; C, left lateral view of carapace.

FIGURE 5. Cyrtomaia polynesica n. sp ... Male holotype (30.2 x 32.2 mm) (MNHN­B 31237). A, first left gonopod, ventral view; B, first left gonopod, dorsal view; C, D, close view of the gonopod, anterior part. (Scale bar = 1.0 mm).