Ethusina paralongipes Chen, 1993

Castro, Peter, 2005, Crabs of the subfamily Ethusinae Guinot, 1977 (Crustacea, Decapoda, Brachyura, Dorippidae) of the Indo-West Pacific region, Zoosystema 27 (3), pp. 499-600 : 568-569

Ethusina paralongipes Chen, 1993

Ethusina paralongipes Chen, 1993: 336 (key), 339, fig. 18. — Ng & Ho 2003: 72 (list).

Ethusina longipes – Chen 2000: 428 (not E. longipes Chen, 1987 ).

Ethusina saltator Ng & Ho, 2000: 81 , figs 14, 15.

TYPE MATERIAL. — Holotype of Ethusina paralongipes Chen, 1993 : cl 6.1 mm, cw 5.7 mm, MUSORSTOM 5, stn CP 324 ( MNHN-B 22254 ); allotype: cl 7.1 mm, cw 7.6 mm, MUSORSTOM 5, stn CP 324 ( MNHN-B 22255 ).

Type material of Ethusina saltator Ng & Ho, 2003 : holotype: cl 6.4 mm, cw 6.4 mm, TAIWAN 2001, stn CD 139 ( NTOU).

TYPE LOCALITY. — Chesterfield Islands, Coriolis Bank, 21°15.01’S, 157°51.33’E, 970 m.

MATERIAL EXAMINED. — Taiwan. TAIWAN 2001, stn CD 139, 22°10.73’N, 120°14.1’E, 852- 718 m, 23.XI.2001, 1 holotype of E. saltator Ng & Ho, 2003 ( NTOU).

Solomon Islands. SALOMON 1, stn CP 1753, 09°02.7’S, 159°49.4’E, 1001-1012 m, 26.IX.2001, 1 ( MNHN-B 28677). — Stn CP 1754, 09°00.1’S, 159°49.0’E, 1169-1203 m, 26.IX.2001, 1, 1 undet. sex ( MNHN-B 28678). — Stn CP 1755, 08°58.2’S, 159°41.6’E, 1288 -1313 m, 26. IX. 2001, 1 ( MNHN-B 28713). — Stn CP 1807, 09°42.2’S, 160°52.8’E, 1077 -1135 m, 2.X. 2001, 2 ( MNHN-B 28679), 1, 1 ( MNHN-B 28683). — Stn CP 1858, 09°37.0’S, 160°41.7’E, 435-461 m, 7.X.2001, 1 ovig. ( MNHN-B 28668).

Vanuatu. MUSORSTOM 8, stn CP 956, 20°33.41’S, 169°35.95’E, 1175-1210 m, 20.IX.1994, 1 ( MNHN-B 27511). — Stn CP 1110, 14°49.16’S, 167°15.18’E, 1360 m, 8.X.1994, 1 ( MNHN-B 27510).

Chesterfield Islands. MUSORSTOM 5, stn CP 324, 21°15.01’S, 157°51.33’E, 970 m, 14.X.1986, 1 holotype ( MNHN-B 22254), 1 allotype ( MNHN- B 22255).

New Caledonia. BATHUS 1, stn CP 651, 21°41.80’S, 166°40.10’E, 1080-1180 m, 11.III.1993, 1 ( MNHN-B 28658), 2 ( MNHN-B 29427).

BATHUS 2, stn CP 767, 22°10.47’S, 165°59.10’E, 1050-1450 m, 17.V.1993, 1 ( MNHN-B 28659).

DISTRIBUTION. — Taiwan ( Ng & Ho 2003, as E. saltator ), Vanuatu ( Chen 2000, as E. longipes ), Chesterfield Is ( Chen 1993), and now from the Solomon Is and New Caledonia. Depth: 435-1450 m ( Fig. 34 ).

SIZE. — Maximum size: cl 8.6 mm, cw 8.1 mm ( MNHN-B 28713), cl 7.1 mm, cw 7.6 mm ( MNHN-B 22255).

REMARKS

Ethusina paralongipes is very close to E. longipes Chen, 1997 , which is known only from Madagascar. Both species are characterized by very long and slender P2 and P3 that extend well over the frontal teeth when folded and long outer orbital teeth that are directed outwardly. Morphological differences between the two species are given in the discussion of E. longipes (see above). An additional diagnostic character of E. paralongipes is eye peduncles that are longer than in E. longipes . The peduncles and the eyes are visible in dorsal view, even sometimes extending outside the outer orbital teeth in the case of males ( Chen 1993: fig. 18a). The G1 are characterized by a small, spur-like processes at each tip. The G1 are more pointed than the pleopod illustrated by Chen (1993: fig. 18d).

As in E. robusta ( Miers, 1886) , the carapace of males is characterized by a raised anterior border, which is accentuated by the presence of a groove that forms a bilobed region just posterior to the frontal teeth. Also similar to the males of E. robusta are long eye peduncles that may be visible beyond the outer margins of the outer orbital teeth. E. paralongipes is easily distinguished from E. robusta by its characteristic long and slender P2 and P3.

Comparison of the holotype ( NTOU) of E. saltator Ng & Ho, 2003 , with the holotype ( MNHN- B 2 2 2 5 5) and several other specimens of E. paralongipes has shown that both are conspecific. E. saltator was described from one specimen. It was distinguished from other Indo-West Pacific species of Ethusina by differences in the length of the median frontal teeth (“being much shorter than the lateral spine”) and the morphology of the G1 (“medially twisted”, “tip is prominently clefted medially”) of the holotype ( Ng & Ho 2003: 83). The relative length of the frontal teeth is clearly a variable character. No difference was found on the apparent twisting of the G1, and the cleft observed in the G1 of the holotype of E. saltator seems to be the result of the insertion of the G 2 in both G1.

Figures

FIG. 34. — Bathymetric distribution of Indo-West Pacific ethusine crabs.