Ethusa orientalis Miers, 1886

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 : 538-540

Ethusa orientalis Miers, 1886

( Fig. 14 )

Ethusa orientalis Miers, 1886 : xxiv, 330, pl. 28, fig. 1, 1a-e. — Doflein 1904: 27, 291 (list), fig. 64. — Ihle 1916b: 153 (list), 155 (list). — Serène 1968: 40 (list). — Serène & Lohavanijaya 1973: 34 (key). — Chen 1993: 318 (key), 319 (list).

Ethusa major Chen, 1993: 318 (key), 326, fig. 8; 2000: 427.

Ethusa minuta – Chen 2000: 427 (part).

TYPE MATERIAL. — Lectotype of Ethusa orientalis Miers, 1886 , cl 15.7 mm, cw 15.1 mm, Challenger, stn 173A ( BMNH 84-44 ); paralectotype:

cl 17.3 mm, same location ( BMNH 84-44).

Miers (1886) based his description on two specimens without selecting a holotype. One of the two syntypes, a male specimen, is hereby designated the lectotype and the second specimen, a male with a damaged carapace, is the paralectotype.

Type material of Ethusa major Chen, 1993 : holotype: 1 cl 16.5 mm, cw 15.9 mm, MUSORSTOM 6, stn

DW 413 ( MNHN-B 21520 ) ; paratype: 1

cl 17.4 mm, cw 17.3 mm, same station ( MNHN-B 22257).

TYPE LOCALITY. — Fiji, E of Kadavu island, 19°9.5’N, 179°41.9’E, 567 m.

MATERIAL EXAMINED. — Vanuatu. MUSORSTOM 8, stn CP 963, 20°20.10’S, 169°49.08’E, 400-440 m, 21.IX.1994, 2 ( MNHN-B 27508). — Stn CP 1124, 15°01.72’S, 166°56.51’E, 532-599 m, 9.X.1994, 1 ( MNHN-B 27504).

New Caledonia. BATHUS 2, stn CP 737, 23°03.42’S, 166°59.97’E, 350-400 m, 13.V.1993, 1 ( MNHN-B 28626).

BATHUS 3, stn DW 797, 23°35’S, 169°37’E, 657- 660 m, 26.XI.1993, 1 ovig. ( MNHN-B 28613).

HALIPRO 1, stn CH 880, 23°03’S, 166°58’E, 450- 491 m, 31.III.1994, 1 ( MNHN-B 28627).

Loyalty Islands. MUSORSTOM 6, stn DW 413, 20°40.10’S, 167°03.50’E, 463 m, 15.II.1989, 1 holotype of E. major ( MNHN-B 21520), 1 paratype of E. major ( MNHN-B 22257).

Fiji. Challenger, stn 173A, 19°9.5’N, 179°41.9’E, 567 m, 1 lectotype, 1 paralectotype ( BMNH 84- 44).

MUSORSTOM 10, stn CP 1330, 17°09.5’S, 177°56.3’E, 567-699 m, 8.VIII.1998, 1 ( MNHN- B 28634). — Stn CP 1342, 16°46.0’S, 177°39.7’E, 650-701 m, 10.VIII.1998, 1 ( MNHN-B 28536).

BORDAU 1, stn DW 1408, 16°02’S, 179°30’W, 550-561 m, 26.II.1999, 1 ( MNHN-B 28631). — Stn DW 1409, 16°02’S, 179°30’W, 557-558 m, 26.II.1999, 1 juv., 4, 1 ( MNHN-B 28632). — Stn DW 1432, 17°20’S, 178°44’W, 477-493 m, 2.III.1999, 2 ( MNHN-B 28633). — Stn DW 1460, 18°47’S, 178°47’W, 750-767 m, 6.III.1999, 1, 1 ( MNHN-B 28630). — Stn DW 1481, 20°57’S, 178°45’W, 441-506 m, 9.III.1999, 1 ( MNHN-B 28628). — Stn CP 1491, 18°50’S, 178°27’W, 777-787 m, 11.III.1999, 2 ( MNHN- B 28537). — Stn DW 1496, 18°43’S, 178°23’W, 392-407 m, 12.III.1999, 1 ( MNHN-B 28629).

Wallis and Futuna Islands. MUSORSTOM 7, stn DW 557, 11°48’S, 178°18’W, 600-608 m, 19.V.1992, 1 ( MNHN-B 28700). — Stn DW 594, 12°31’S, 174°20’W, 495-505 m, 24.V.1992, 1 ( MNHN-B 28614).

Tonga. BORDAU 2, stn 1528, 21°14’S, 174°59’W, 587-592 m, 15.VI.2000, 1, 2 ( MNHN-B 28639). — Stn 1541, 21°15’S, 175°14’W, 319-333 m, 5.VI.2000, 1 ( MNHN-B 28640). — Stn 1553, 20°42’S, 174°54’W, 650-676 m, 6.VI.2000, 1 ( MNHN-B 28699). — Stn 1556, 20°11 ’S, 174°45’W, 589-591 m, 7.VI.2000, 2 ( MNHN-B 28635). — Stn 1600, 20°48’S, 174°52’W, 902- 907 m, 15.VI.2000, 1 ( MNHN-B 28637). — Stn 1641, 21°09’S, 175°22’W, 395 m, 21.VI.2000, 1 ( MNHN-B 28636). — Stn 1642, 21°05 ’S, 175°23’W, 532 m, 21.VI.2000, 1, 1 juv.

( MNHN-B 28641). — Stn 1643, 21°05 ’S, 175°22’W, 487 m, 22.VI.2000, 1 ( MNHN-B 28638). — Stn 1644, 21°05’S, 175°23’W, 501 m, 22.VI.2000, 2 ( MNHN-B 28642).

DISTRIBUTION. — Vanuatu ( Chen 2000, as Ethusa major Chen, 1993 ), Fiji ( Miers 1886) and now from New Caledonia, Loyalty Is, Wallis and Futuna Is, and Tonga. Chen (2000: 427) erroneously recorded it (as E. major ) from Indonesia, Chesterfield Is, and New Caledonia. The type locality of E. major is the Loyalty Is. Depth: 319-907 m ( Fig. 34 ).

SIZE. — Maximum size: cl 15.9 mm, cw 15.6 mm ( MNHN-B 28628), cl 17.4 mm, cw 17.3 mm ( MNHN-B 22257).

REMARKS

The description and the illustration of Ethusa orientalis by Miers (1886) clearly show its diagnostic features: broadly triangular and pointed outer orbital teeth that are almost as long as the frontal teeth and a granular carapace with nearly straight lateral borders that diverge toward the posterior border ( Fig. 14A ; Miers 1886: pl. 29, fig. 1). The dense and conspicuous granulation of the dorsal and ventral surfaces of the carapace is also observed on the abdomen of both sexes and on the third maxillipeds. Also characteristic is the endostome, in which the anterior border reaches the proximal border of the antennular fossae of the basal antennular articles ( Miers 1886: pl. 29, fig. 1a). These diagnostic features were confirmed in the type material.

The outer orbital teeth, which are nearly symmetrical in small specimens, become clearly asymmetrical in the largest individuals. In many of these specimens the inner margin of both or one of the teeth becomes swollen. The tip of the teeth may also become narrower and more acute, as in the case of a female from the Wallis and Futuna Is (cl 10.9 mm, cw 10.2 mm, MNHN-B 28700).

A suture is present between the second and third thoracic sternites (sternal suture 2/3). Although fused in the largest individuals, the suture is made apparent by the presence of a prominence running along its anterior border. The P2 and P3 are relatively short and thick. Although the male abdomen was described as “distinctly seven-jointed” and shown as such in two figures ( Miers 1886: 330, pl. 28, fig. 1b, e), the lectotype and paralectotype specimens have somites 3-5 fused. The fused sutures do show faintly in the type specimens but the somites are undoubtedly fused and rigid when observed underneath the abdomen. Somite 6 was found to be fused to somites 3-5 in a few other specimens.

Ethusa major Chen, 1993 was described from two females collected in the Loyalty Is, although the type locality was erroneously given as “ New Caledonia ” ( Chen 1993: 327). E. major was described as being “very similar” to E. orientalis but it was separated from the latter by having a carapace that was “entirely covered with pubescence, sparse short setae, and indistinct granules” ( Chen 1993: 327). There is no evidence that Chen examined the type material of E. orientalis . Long, thin hairs fringe the anterior and anterolateral borders of the carapace of E. orientalis , a character that was not mentioned or illustrated by Miers nor clearly shown by the type specimens, where only the proximal portions of some of the hairs remain. Pubescence is certainly a variable character in E. orientalis . The conspicuous pubescence shown in Chen’s drawing of the holotype of E. major ( Chen 1993: fig. 8) could not be confirmed in the actual specimen, even if Chen stated that her species has “indistinct granules”. Furthermore, the type specimens of E. major actually showed the conspicuous granulation characteristic of E. orientalis . The placement of E. major as a junior subjective synonym of E. orientalis is confirmed by the examination of the type material of both species (see Material examined) as well as material identified as E. major by Chen (, MNHN-B 27504 [ Chen 2000: 427];, MNHN-B 28626;, MNHN-B 28627). A comparison of the G1 and G2 of both species confirms the synonymy.

The G1 and G2 of E. orientalis are illustrated here for the first time. The G1 ( Fig. 14B ) are slender, straight, each with a slightly pointed tip, distal ends smooth, without a notch; each G2 ( Fig. 14C ) has a simple, slightly curved, pointed tip. The morphology of the G1 is the most reliable way to separate E. orientalis from E. magnipalmata Chen, 1993 , and E. granulosa Ihle, 1916 , all three of which are very similar in their general morphology (see discussion of these two species). Similarities between E. orientalis and E. foresti are outlined in the discussion of E. foresti (see above). Doflein (1904: 27) compared the males of E. orientalis with those of E. andamanica .

Figures

FIG. 14. — Ethusa orientalis Miers, 1886, lectotype cl 15.7 mm, cw 15.1 mm, Fiji, E of Kadavu, Challenger, stn 173A, 567 m (BMNH 84-44); A, dorsal surface of carapace; B, left G1, ventral (left) and dorsal (right) views; C, right G2, dorsal view. Scale bars: A, 3 mm; B, C, 2 mm.

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