Ethusina alcocki, Ng & Ho, 2003

Ng, Peter K. L. & Ho, P. - H., 2003, On The Deep-Water Dorippid Crabs Of The Genus Ethusina Smith, 1884 (Crustacea: Decapoda: Brachyura) From Taiwan, Raffles Bulletin of Zoology 51 (1), pp. 71-85 : 74-75

Ethusina alcocki , new species

( Figs. 4 , 5 )

Ethusina investigatoris – Chen & Xu, 1991: 60, Fig. 9 (not E. investigatoris Alcock, 1896 )

Material examined. – Holotype - female, 8.2 by 9.8 mm ( NTOU), Station CP 32, 22 01.7’N, 120 11.1’E, 910-1129 m, coll. TAIWAN 2000, R. V. “Fishery Researcher 1”, 30 Jul.2000.

Etymology. – This species is named after A. Alcock, whose contributions to Indian carcinology have not been rivalled.

Remarks. – Ethusina alcocki , new species, is rather close to E. investigatoris Alcock, 1896 , but three characters argue against its inclusion there. In E. investigatoris , the median frontal teeth are more prominent, with the inner margin more convex, the supraorbital margin is relatively narrower, and the dactylus of the P2 and P3 is about one-third shorter and relatively broader (cf. Alcock, 1896: 295; Alcock & MacGilchrist, 1905: Pl. 72 fig. 3). Chen (1986b: 135, Fig. 14 ) referred a male specimen from China to E. investigatoris , and this seems to be correct. Chen & Xu (1991: 60, Fig. 9 ) subsequently reported E. investigatoris from the South China Sea, but the external orbital spine of the male specimen she figured is relatively shorter with the median frontal teeth subequal in length (rather than with the outer tooth longer). Recently, through the courtesy of H.-L. Chen, the first author had an opportuinity to examine a second specimen from the South China Sea which had been identified as “ E. investigatoris ” and is almost identical to that described by Chen & Xu (1991). We have no doubt that this specimen is conspecific with what is here identified as E. alcocki . Unfortunately, the original specimens described in Chen (1986) and Chen & Xu (1991) could not be located for direct comparisons as the IOCAS is currently moving its catalogued collections to a new building and the material is not available for study (H.-L. Chen, pers. comm., September 2002).

Alcock (1896: 285) described E. investigatoris from the Laccadive Sea and Bay of Bengal, in the Indian Ocean, noting that the elongated external orbital spine is “needlelike” but “falls considerably short of the tips of the rather long acute frontal spines” (see also Alcock & MacGilchrist, 1905: Pl. 72 fig. 3), and felt that it was very close to E. gracilipes ( Miers, 1886) . Ethusina alcocki , however, differs from E. gracilipes in having the external orbital spine relatively longer, reaching to the tip of the frontal spines (not falling short of it), and the inner median teeth are also lower and are not spiniform.

Figures

Fig. 4. Ethusina alcocki, new species. A, B, holotype female, 8.2 by 9.8 mm (NTOU); C, female, 8.8 by 9.5 mm (IOCAS). A, C, overall view; B, carapace.

Fig. 5. Ethusina alcocki, new species. Holotype female, 8.2 by 9.8 mm (NTOU). A, carapace; B, left orbit, antenna and antennule; C, right P2; D, right P5; E, left chela. Scales: A-C = 5.0 mm; D, E = 1.0 mm.

Fig. 9. Ethusina macrospina, new species. A, paratype female, 8.6 by 9.2 mm (ZRC); paratype female, 9.4 by 10.7 mm (NTOU); C, paratype female, 10.7 by 11.2 mm (ZRC); D, paratype female, 9.8 by 10.1 mm (NTOU).

Fig. 14. Ethusina saltator, new species. Holotype male, 5.9 by 6.8 mm (NTOU). A, overall view; B, carapace.