Ethusa indica Alcock, 1894

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 : 527-529

Ethusa indica Alcock, 1894

( Figs 12 ; 33C )

Ethusa indica Alcock, 1894: 405 ; 1896: 283; 1899: 32. — Doflein 1904: 291 (list), fig. 64. — Ihle 1916b: 138, 151 (list), 153 (list), 155 (list). — Sakai 1965: 24, pl. 12, fig. 4 (colour); 1976: 64, fig. 27. — Serène 1968: 40 (list). — Serène & Lohavanijaya 1973: 34 (key). — Miyake 1983: 198 (list). — Chen 1985: 189, figs 8, 9, pl. 2, fig. 5; 1986: 128, fig. 10; 1993: 317 (key), 324; 1997: 618; 2000: 426. — Dai et al. 1986: 52, fig. 27(3-4), pl. 6, fig. 2. — Dai & Yang 1991: 59, fig. 27(3-4), pl. 6, fig. 4. — Nagai 1995: 60, pl. 1, fig. 6. — Ikeda 1998: 26, pl. 15 (colour). — Muraoka 1998: 17. — Takeda 2001: 224, 254, 259. — Chen & Sun 2002: 54, 240, fig. 101, pl. 9, fig. 8. — Marumura & Kosaka 2003: 23.

Aethusa indica – Alcock & Anderson 1895: pl. 14, fig. 2.

Ethusa gracilipes – Serène & Lohavanijaya 1973: 35 (key), 35, figs 56-59, pl. 4, figs C, D (not Ethusina gracilipes ( Miers, 1886)) .

Ethusina gracilipes – Serène & Vadon 1981: 119, 121 (not Ethusina gracilipes ( Miers, 1886)) .

Ethusa serenei Sakai, 1983a: 5 , 27.

? Ethusa sp. – Türkay 1986: 146, figs 30-32.

TYPE MATERIAL. — Unknown (Zoological Survey of India, Calcutta?).

A specimen (cl 9.1 mm, cw 9.6 mm, ZMUC CRU3727) originally at the Indian Museum, Calcutta (now Zoological Survey of India) but donated to ZMUC by A. Alcock and identified by him as Ethusa indica may have been part of the type material.

The location of the type material of Ethusa serenei Sakai, 1983 , a junior subjective synonym, is unknown. TYPE LOCALITY. — Andaman Sea, 439 m.

MATERIAL EXAMINED. —? Red Sea. Valdivia , stn VA 22-121 TA, 12°26.5’N, 38°38.3’E, 779-801 m, 15.IV.1979, 1 ( SMF 13587).

Gulf of Aden. Meteor, cruise 5, stn 249 Ku, 12°29.5’N, 45°38.7’E, 1299-1314 m, 8.III.1987, 1 ( SMF 29341).

Southwestern Indian Ocean. Marion Dufresne, campagne MD/32, stn CA 76, 21°16.0’S, 55°17.6’E, 450- 937 m, 24.VIII.1986, 1 ovig. (MNHN-B 28559).

India. Off Travancore (= Kerala) coast, 743 m, from Indian Museum, A. Alcock ded., 1898, 1 ( ZMUC CRU3727).

Japan. Honshu, Izu Peninsula, Suruga Bay, off Toi, 34°52.05’N, 138°42.63’E, 550 m, T. Komai coll., 21.III.2001, 1, 1 ( CBM-ZC 6254).

Shikoku, Tosa Bay, ex. T. Sakai, 1 ( BMNH 1961.6.5.21). — Tosa Bay, off Mimase, refuse from fishing nets, XII.1961, K. Sakai coll., 6, 1 parasitized by bopyrid ( SMF 28922). — Tosa Bay, off Mimase, refuse from fishing nets, K. Sakai coll., 1 ovig. ( SMF 28921), 1 ( SMF 28928), 1 ( SMF 28931).

Philippine Islands. South China Sea, MUSORSTOM 2, stn CP 18, 14°00’N, 120°18’E, 188-195 m, 22.XI.1980, 1 ovig. ( MNHN-B 18159). — Stn CP 25, 13°39’N, 120°42’E, 520-550 m, 23.XI.1980, 1 undet. sex, parasitized by bopyrid (MNHN-Ep). — Stn CP 25?, parasitized by bopyrid, 1 ( MNHN- Ep), parasitized by bopyrids, 2 (MNHN-Ep). — Stn CP 39, 13°03’N, 122°36’E, 1030-1190 m, 25.XI.1980, 2 ( MNHN-B 18164).

MUSORSTOM 3, stn CP 106, 13°47’N, 120°30’E, 640-668 m, 2.VI.1985, 2, 1, 1 ovig.

( MNHN-B 18926).

Indonesia. Makassar Strait, CORINDON 2, stn CH 280, 01°59’S, 119°10’E, 715-800 m, 8.XI.1980, 6, 7 ( MNHN-B 19069).

Moluccas, Siboga , stn 137, between Makian island and Halmahera, 00°23.8’N, 127°29’E, 472 m, 3.VIII.1899, 3 juv., 1 ( ZMA Crust.De 241682).

Lesser Sunda Islands, Siboga , stn 314, Flores Sea, N of Sumbawa, 07°36’S, 117°30.8’E, 694 m, 17.II.1900, 1 ( ZMA Crust.De 241680). — Stn 52, S of western tip of Flores, 09°3.4’S, 119°56.7’E, 959 m, 20.IV.1899, 1, 1 juv. ( ZMA Crust.De 241681). Tanimbar Islands, KARUBAR, stn CP 53, 08°18’S, 131°41’E, 1026-1053 m, 30.X.1991, 1 ovig.

( MNHN-B 22871). — Stn CP 89, 08 °39’S, 131°08’E, 1084- 1058 m, 5.XI.1991, 4, 4,

2 ovig. ( MNHN-B 22860).

Kai Islands, KARUBAR, stn CP 12, 05 °18’S, 131°41’E, 436- 413 m, 23.X. 1991, 1, 3 ( MNHN-B 22867).

Solomon Islands. SALOMON 1, stn CP 1783, 08°32.8’S, 160°41.7’E, 399-700 m, 29.IX.2001, 1 juv. cl 5.4 mm, cw 5.4 mm ( MNHN-B 28703), 1 ( MNHN-B 28705). — Stn CP 1858, 09°37.0’S, 160°41.7’E, 435-461 m, 7.X.2001, 1 ( MNHN-B 28571). — Stn CP 1859, 09°32.6’S, 160°37.3’E, 283- 305 m, 7.X.2001, 1 ovig. ( MNHN-B 28562).

Vanuatu. MUSORSTOM 8, stn CP 1036, 18°01.00’S, 168°48.20’E, 920-950 m, 29.IX.1994, 1 ( MNHN-B 28560).

New Caledonia. BATHUS 1, stn CP 660, 21°10.48’S, 165°53.19’E, 786-800 m, 13.III.1993, 4, 2 ( MNHN-B 28577). — Stn CP 661, 20°05’S, 165°50’E, 960-1100 m, 13.III.1993, 1 ( MNHN-B 28506). — Stn CP 709, 21°41.8’S, 166°37.9’E, 650-800 m, 19.III.1993, 1 ( MNHN-B 28580).

BATHUS 2, stn CP 743, 22°35.56’S, 166°26.23’E, 713-950 m, 14.V.1993, 2 ( MNHN-B 28581). — Stn CP 771, 22°09.52’S, 166°01.75’E, 610-800 m, 18.V.1993, 1 ( MNHN-B 28579).

HALIPRO 1, stn CP 854, 21°40’S, 166°38’E, 650- 780 m, 19.IV.1994, 1 ( MNHN-B 28578). — Stn CP 867, 21°26’S, 166°18’E, 720-950 m, 22.IV.1994, 1 ( MNHN-B 28582).

BIOGEOCAL, stn CP 232, 21°33.81’S, 166°27.07’E, 760-790 m, 12.IV.1987, 2, 1 ovig. ( MNHN- B 19098).

Loyalty Islands. MUSORSTOM 6, stn CP 438, 20°23.00’S, 166°20.10’E, 780 m, 18.II.1989, 1 ( MNHN-B 21522).

Fiji. MUSORSTOM 10, stn CP 1316, 17°14.8’S, 178°22.0’E, 478-491 m, 6.VIII.1998, 3, 2,

1 parasitized by Sacculina sp. ( MNHN-B 28567). — Stn CP 1317, 17°12.0’S, 178°14.1’E, 471-475 m, 6.VIII.1998, 1, 3, 1 parasitized by Sacculina sp. ( MNHN-B 28569). — Stn CP 1332, 16°56.2’S, 178°07.9’E, 640-687 m, 8.VIII.1998, 1, 1 ( MNHN-B 28566). — Stn CP 1342, 16°46.0’S, 177°39.7’E, 650-701 m, 10.VIII. 1998, 1 ( MNHN-B 28561). — Stn CP 1346, 17°19.6’S, 178°32.4’E, 673-683 m, 11.VIII. 1998, 1 ( MNHN-B 28570). — Stn CP 1360, 17°59.6’S, 178°48.2’E, 402-444 m, 13.VIII. 1998, 1 ( MNHN-B 28564).

BORDAU 1, stn CP 1396, 19°39’S, 179°57’W, 591- 596 m, 24.II.1999, 1, 2 ( MNHN-B 28572). — Stn CP 1398, 16°22’S, 179°56’W, 907-912 m, 24.II.1999, 4, 1 juv., 1 ( MNHN-B 28565). — Stn CP 1400, 16°28’S, 179°50’W, 1004-1012 m, 25.II.1999, 2 ( MNHN-B 28625). — Stn CP 1406, 16°39’S, 179°37’W, 360-380 m, 25.II.1999, 1 ( MNHN-B 28563).

Tonga. BORDAU 2, stn CP 1565, 20°58 ’S, 175°16’W, 869-880 m, 9.VI.2000, 1, 1 ovig.

( MNHN-B 28568).

DISTRIBUTION. — Maldives, India, Sri Lanka, and Andaman Sea (see Alcock 1896); Japan (see Sakai 1976); East China Sea ( Chen 1986); South China Sea ( Serène & Lohavanijaya 1973, as Ethusa gracilipes Miers, 1886 ); Philippine Is ( Serène & Vadon 1981, as Ethusina gracilipes ( Miers, 1886) ; Chen 1985, 1993); Indonesia (Lesser Sunda Is and Moluccas [ Ihle 1916b], Makassar Strait, Tanimbar and Kai Is [ Chen 1993, 1997]); Vanuatu ( Chen 2000); New Caledonia ( Chen 1993), and now from the Gulf of Aden, southwestern Indian Ocean near La Réunion, Solomon Is, Fiji, and Tonga; questionably from the Red Sea ( Türkay 1986, as Ethusa sp. ) ( Fig. 12 ). Depth: 21- 1315 m ( Chen 1993) ( Fig. 34 ).

SIZE. — Maximum size: cl 14.6 mm, cw 15.9 mm ( MNHN-B 28505), cl 16.7 mm, cw 18.3 mm ( MNHN-B 28505), no sex indicated: cl 20.1 mm, cw 17.7 mm ( Ikeda 1998: pl. 15).

REMARKS

Ethusa indica is best characterized by outer orbital teeth that are typically conspicuously slen- der, acute, directed outwardly, and reach higher than the frontal teeth ( Fig. 33C ; Alcock & Anderson 1895: pl. 14, fig. 2; Sakai 1965: pl. 12, fig. 4; 1976: fig. 27; Chen 1985: fig. 8; 1986: fig. 10.46; Chen & Sun 2002: fig. 101.2). The relative length, width, and orientation of the outer orbital teeth, however, vary widely, as pointed out by Chen (1985: 191, fig. 9b). The anterior border of the endostome extends well below the antennular fossae of the basal antennular articles ( Sakai 1976: 62-63 [key]; Chen 1985: fig. 9a). The meri of P2 and P3 are conspicuously long and, when folded, are longer than the carapace ( Fig. 33C ; Sakai 1976: fig. 27). Their length, however, is also variable ( Chen 1985: 191). A good diagnostic character is the G1, each having an expanded, triangular, shovel-like distal end ( Chen 1985: fig. 9e, f; 1986: fig. 10.49; Chen & Sun 2002: fig. 101.5). The presence of a minute triangular spine at the inner, distal portion of each of the basal antennular articles, a character mentioned by Serène & Lohavanijaya (1973: 36) for specimens of E. indica misidentified as Ethusa gracilipes Miers, 1886 (see below), is actually a character of all ethusines.

Ethusa indica is similar to E. latidactyla Parisi, 1914 , a large-size species. Both species are easily separated by the relative length of their outer orbital teeth, which in E. latidactyla ( Sakai 1937: fig. 1b; 1976: fig. 26b; Chen 1985: fig. 7; 1986: fig. 9.41; Chen & Sun 2002: fig. 105.1) are shorter and wider than those of E. indica . The outer orbital teeth are also slightly shorter t h a n t h e f r o n t a l t e e t h i n E. l a t i d a c t y l a i n contrast to E. indica , where they are longer. The anterior border of the endostome extends to the level of the antennular fossae of the basal antennular articles in E. latidactyla but it extends well below the articles in E. indica . There are also some similarities with E. abbreviata n. sp. and E. machaera n. sp. Differences between the species are given in the respective descriptions of the two species.

A female collected near La Réunion in the southwestern Indian Ocean ( MNHN-B 28559) had one unusually long outer orbital tooth (the other tooth was cut off) but all other characters agree with those of E. indica .

Specimens identified as Ethusa gracilipes by Serène & Lohavanijaya (1973: 35) and as Ethusina gracilipes by Serène & Vadon (1981: 119, 121) appear to be conspecific to E. indica , as previously indicated by Chen (1985: 189, 191). The specimens, however, could not be located.

Ethusa serenei Sakai, 1983 was described from the (East?) China Sea and considered identical to the specimens identified as Ethusina gracilipes by Serène & Lohavanijaya (1973). The type material could not be located but Sakai’s illustration ( Sakai 1983a: pl. 4, fig. 3) agrees with the diagnostic features of E. indica . Chen (1985: 189) listed E. serenei as a synonym of E. indica without explanation.

A specimen of a small, juvenile ethusid from the Red Sea identified as Ethusa sp. by Türkay (1986) may belong to E. indica . The specimen (, SMF 13587) survives as a soft molt and a much fragmented portion of the ventral surface of the carapace, but a drawing ( Türkay 1986: figs 30-32) shows characters similar to those of E. indica : acute outer orbital teeth that are direct- ed outwardly and G1 each with an expanded, triangular distal end.

Figures

FIG. 12. — Geographical distribution of Ethusa indica Alcock, 1894.

FIG. 33. — A, Ethusa granulosa Ihle, 1916, cl 14.7 mm, cw 14.6 mm, Vanuatu, west coast of Malekula, MUSORSTOM 8, stn DW 1061, 458-512 m (MNHN-B 28698) (photograph by J.-L. Menou, IRD, Nouméa); B, Ethusa hawaiiensis Rathbun, 1906, cl 6.7 mm, cw 6.2 mm, Vanuatu, S of Anatom, MUSORSTOM 8, stn CP 963, 400-440 m (MNHN-B 28538) (photograph by J.-L. Menou, IRD, Nouméa); C, Ethusa indica Alcock, 1894, cl 7.8 mm, cw 7.8 mm, Vanuatu, SE of Éfaté, MUSORSTOM 8, stn CP 1036, 920-950 m (MNHN-B 28560) (photograph by J.-L. Menou, IRD, Nouméa); D, Ethusina challengeri (Miers, 1886), cl 25.9 mm, Mid-Indian Basin, SAFARI 2, stn 35, trawl CP 29, 4950-4928 m (MNHN-B 28697) (photograph by P. Briand, IFREMER); E, Ethusina macrospina Ng & Ho, 2003, cl 10.4 mm, cw 11.0 mm, Taiwan, off southwest coast, TAIWAN 2003, stn CD 203, 635-868 m (NTOU) (photograph by T.-Y. Chan, NTOU).

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