Hyastenus sebae White, 1847

Shaga, I Bevin, Priya, K, Ramar, Selvakumar, Srinidhi, S, Mohan, G Chandra, Ranganathan, Sukanya, Moulvi, S M M & Mani, Bhuvaneswari, 2023, A Small Collection of Subtidal Crabs (Crustacea: Decapoda: Brachyura) from the Palau Islands Collected by Dredging, Bulletin of the National Museum of Nature and Science. Series A, Zoology 49 (1), pp. 7-42 : 9-10

Hyastenus sebae White, 1847

( Fig. 1E )

Material examined. Off Kwannon , Koror I., Palau Is., dredged; 1 ♀ (cb 10.5×pcl 13.8 mm; rl 5.8 mm), NSMT-Cr 30957; June 17, 1980; K. Baba leg.

Remarks. Griffin (1966) selected the lectotype specimen from the five specimens in the type series of Hyastenus sebae , with the photographs of the carapace in dorsal and ventral views, and later, Griffin (1976) showed that one specimen in the four paralectotypes of H. sebae belongs to H. convexus Miers, 1884 , and the other three specimens belong to a new species, H. whitei . At present, as shown in Fig. 1E, H . sebae is characteristic in having the strongly tuberculated carapace, with the short rostral spines, and readily distinguished from H. whitei in which the rostral spines are remarkably long, nearly as long as the pcl.

Hyastenus oryx A. Milne-Edwards, 1872 , is known as synonymous with H. sebae , and the

validity of H. cornigerus Sakai, 1938 , is not decided, but is probably identical with H. sebae . In the original description of H. cornigerus , the relationships to the other species were not mentioned at all. Griffin and Tranter (1986) examined many specimens referable to H. sebae , and mentioned that H. cornigerus is not distinguished from H. sabae at least as far as the description concerned, with the supporting evidences that Takeda (1973) recorded H. oryx from the Palau Islands, and a specimen from the Palau Islands identified as H. cornigerus by Dr. T. Sakai is preserved in the National Museum of Natural History, Smithsonian Institution, U.S.A.

Distribution. Japan (as H. cornigerus ), many localities in the Philippines and Indonesian waters, Singapore, the Palau Islands, New Caledonia, and Western Australia. The bathymetric records are mostly in shallow waters from intertidal zone to at most ca. 50 m, but there are some unusual deep-water records from the Java Sea (538 m) and the Kai Islands (304 and 385 m) by Griffin and Tranter (1986).

Figures

Fig. 1. A–C: Thusaenys calvarius (Alcock), ♂ (NSMT-Cr 30959; cb 6.7×pcl 10.5mm excluding posterior tubercle). D: Naxioides hirta A. Milne-Edwards, ♂ (NSMT-Cr 30958; cb 17.0mm excluding branchial spines× pcl 25.2mm including posterior tubercle). E: Hyastenus sebae White, ♀ (NSMT-Cr 30957; cb 10.5×pcl 13.8mm).