Oxypleurodon sanctaeclausi, Forges, Bertrand Richer De & Ng, Peter K. L., 2009

Forges, Bertrand Richer De & Ng, Peter K. L., 2009, New genera, new species and new records of Indo-West Pacific spider crabs (Crustacea: Brachyura: Epialtidae: Majoidea), Zootaxa 2025, pp. 1-20 : 2-5

Oxypleurodon sanctaeclausi n. sp.

Figs. 1A–C , 3 A, B, 11A

Sphenocarcinus luzonicus — Griffin 1976: 211 (only specimen from Jolo Is.). – Serène & Vadon 1981: 124, pl. 4E. – Guinot & Richer de Forges 1986a: 138, fig. 21C–D, pl. 8 fig. E, F. – Guinot & Richer de Forges 1986b: 29. – Richer de Forges 1992: 4.

Rochinia luzonica — Griffin & Tranter 1986: 180. – Tavares 1991: 161. – Webber & Richer de Forges 1995: 514.

Oxypleurodon luzonicus — Richer de Forges 1995: 48, fig. 1B, pl. 2A.

Not Sphenocarcinus luzonicus Rathbun, 1916 , from the east coast of Luzon = Oxypleurodon luzonicum ( Rathbun, 1916) .

Material examined. Philippines. PANGLAO 2005: Stn. CA 2337, 22 May 2007: 1 ovigerous female (18.7 x 16.8 mm, photographed) ( ZRC 2009.0018). – Stn. CP 2344, 9°28.4’N 123°49.6’E, 142–211 m, 23 May 2005: 1 ovigerous female (12.7 x 10.0 mm) ( NMCR). – Stn. CP 2362, 8°55.6’N 23°33.1’E, 700–740 m, 26 May 2005: male holotype (15.1 x 14.4 mm) ( NMCR, ex ZRC 2008.0828) (14.3 x 14.0 mm) ( MNHN B31852), 1 ovigerous female (18.4 x 16.6 mm) ( ZRC 2008.0829). MUSORSTOM 3: stn. CP 105, 13°52'N 120°30'E, 398–417 m, 1 June 1985: 1 male (20.4 x 20.6 mm), 1 ovigerous female (20.6 x 20.0 mm), 1 female (12.2 x 10.7 mm) (MNHN-B 27487). – Stn. CP 133, 11°58'N 121°52'E, 334–390 m, 5 June 1985: 1 male (17.8 x 17.1 mm), 2 ovigerous females (14.2 x 14.1 mm, 16.3 x 15.0 mm), 2 females (13.0 x 12.1 mm, 12.0 x 11.8 mm) (MNHN-B 27488).

Diagnosis. Small-size species (ovigerous female 10–20 mm carapace length). Carapace pyriform. Bifid rostrum with long, sharp spines diverging, curving outwards, prominently V-shaped. Carapace with raised plates: 2 semicircular supraocular plates; 2 subhepatic plates fused with postocular, L-shaped plates; elongated mesogastric plate with large epigastric granule; rounded cardiac plate; 2 branchial plates laterally elongated ending as sharp point; 2 triangular epibranchial plates directed obliquely; long ridge adjacent to posterior border of carapace medially forming point; rounded, small plate below epibranchial plate on lateral border of carapace; small ovoid plate under subhepatic region. Pterygostomian region with raised ovoid plate. Antennae shorter than rostral spines. Antennules deeply inserted in cavity forming sharp angle distally. Buccal frame rectangular with operculiform third maxillipeds. Chelipeds shorter than P2: merus cylindrical; carpus carinated on outer border; propodus slightly inflated, carinated on both borders; dactylus with rounded tooth on proximal third; interior border of fingers distally serrulated. Ambulatory legs with cylindrical articles; P2 longest; dactyli curved, claw-like. Deep grooves of male thoracic sternal sutures. Male abdomen with 7 free somites including telson. G1 relatively straight, distal portion dilated ( Fig. 3 A, B). Females with plates having denser tomentum than in males, long setae on interior border of rostrum. Epigastric tubercle more developed than in male, with 2 smaller tubercles on each side of mesogastric plate. Each side of cardiac plate with 2 small tubercles covered by thick setae.

Etymology. As this species was described and discovered over the Christmas period, naming it after Santa Claus seems appropriate. This is especially in view of its beautiful red and white colours.

Remarks. This species was formerly identified as O. luzonicum , which was described from the Albatross material collected from the Pacific coast (eastern Luzon) of the Philippines by Rathbun (1916: 539). The material recorded in the Philippines by the MUSORSTOM cruises and in Indonesia by the KARUBAR expedition (Richer de Forges 1995: fig. 1B, Pl. 2 A) was also originally attributed to O. luzonicum . Fresh specimens from the Bohol Sea (PANGLAO 2005 expedition) forced us to reappraise its taxonomy, especially since there were marked differences with the holotype of O. luzonicum . Oxypleurodon luzonicum was redescribed and figured in some detail by Griffin (1976: 211, fig. 11a) and Guinot & Richer de Forges (1986: 136, pl. VIII, fig. A–D). We regard the present material as belonging to O. sanctaeclausi n. sp.

Oxypleurodon luzonicum sensu stricto differs from the present specimens from PANGLAO 2005 (Balicasag) and the older material from MUSORSTOM (Lubang) in that the rostral spines are straight and slightly diverging (curved and more prominently diverging in O. sanctaeclausi n. sp.); the mesogastric plate is large and shaped like a lozenge (thin and ovoid in O. sanctaeclausi n. sp.); the cardiac plate is rounded (laterally elongated in O. sanctaeclausi n. sp.); and the fused subhepatic and postocular plates is large (smaller, L-shaped in O. sanctaeclausi n. sp.). These and other differences had already been observed by Guinot and Richer de Forges (1995) but they considered it as individual variation. Their material from station 15 of the MUSORSTOM 2 expedition is not from southeast Luzon as reported but from the north of Lubang in western Philippines. The good series of present specimens indicates it should be regarded as new. The specimen from Indonesia recorded and illustrated by Richer de Forges (1995: fig. 1 B, Pl. 2 A) as “ O. luzonicum ” closely matches O. sanctaeclausi n. sp. and should be referred to the new species.

The new species is found in muddy bottoms from 142 to 740 m (PANGLAO 2005 stations).

Figures

FIGURE 1. A – C, Oxypleurodon sanctaeclausi n. sp., holotype male (15.1 x 14.4 mm) (NMCR, ex ZRC 2008.0828); D – F, Oxypleurodon annulatum n. sp., holotype male (11.1 x 6.5 mm) (NMCR). A, D, overall dorsal views; B, E, lateral views of carapace; C, F, thoracic sternum and abdomen.

FIGURE 3. G 1 s. A, B, Oxypleurodon sanctaeclausi n. sp., holotype male (15.1 x 14.4 mm) (NMCR, ex ZRC 2008.0828); C, D. Oxypleurodon annulatum n. sp., holotype male (11.1 x 6.5 mm) (NMCR); E, F. Oxypleurodon carbunculum (Rathbun, 1906), male (19.9 x 14.4 mm) (BPBM Acc. N ° 1981.136). Scales = 0.5 mm.