Abyssorchomene gerulicorbis, comb. nov.

Abyssorchomene gerulicorbis (Shulenberger & Barnard, 1976) comb. nov.

Orchomene affinis.— Birstein & Vinogradov, 1955: 223, fig. 9.

Orchomene gerulicorbis Shulenberger & Barnard, 1976: 243, figs 1–3.—Thurston, 1979: 56 (biology).— Barnard & Ingram, 1990: 21.— Barnard & Karaman, 1991: 508.

Orchomenella (Orchomenopsis) gerulicorbis.— Palerud & Vader, 1991: 41.— Jones, Collins, Bagley, Addison & Priede (1998): 1124, table 2 (ecology).

Orchomenella gerulicorbis.— Thurston, 1990: 262 Table 3, 264 Table 5, etc. (ecology).—Lowry Stoddart, 1994: 181.— Lowry & Stoddart 2003: 169.— Jamieson, Kilgallen, Rowden, Fujii, Lörz, Kitazawa & Priede, 2011: 53, 55, table 3, 58, table 6 (ecology).—Duffy, Horton & Billet, 2012: 4865, table 3 (ecology).— Corrigan, Horton, Fotherby, White & Hoelzel, 2013: 6 (molecular).— Cousins, Horton, Wigham & Bagley, 2013: 303, table 3 (ecology).

Types. Holotype, female, 13. 9 mm, USNM 149204.

Type locality. 440 miles north of Oahu, Hawaii, (28°00'00"N 155°00'00"W), 5720 m, water temperature, 1.2°C, bottom smooth red mud with Manganese nodules.

Australian material examined. Queensland: 22 specimens, AM P.49519; 4 specimens, AM P.49523; 261 specimens, AM P.50232; 270 specimens, AM P.50239; 21 specimens, AM P.50295; 14 specimens, AM P.57597; 3 specimens, AM P.57601; 10 specimens, AM P.57603; 5 specimens, AM P.57610; 2 specimens, AM P.57613; 1 female, AM P.71842; 14 specimens, AM P.71843, east of Flynn Reef, Queensland, Australia (16°37.82'S 146°23.08'E), 1000 m, baited trap, 7–8 June 1993, J.K. Lowry, P. Freewater & W. Vader, RV Sunbird [QLD-930–QLD932 & QLD-948–QLD-950/ SEAS].

Tasmania. 20 specimens, AM P.73704, Hill D 1, south-southeast of South East Cape (44°23.4'S 147°16.2'E), 1942 m, baited trap, 31 January 1997, CSIRO party on FRV Southern Surveyor, FRV Southern Surveyor [SS01 /97/ 65].

Extralimital material examined: 8 specimens, AM P.40544, San Clemente Basin, California, United States of America (32°29.8'N 117°59.0'W), 1860 m, 05 November 1987, S.C. France, RV Robert Gordon Sproul [114]; 22 specimens, AM P.42143, off Rapa, Austral Isles, French Polynesia, (27°35.3' S 144°15.5'W), 870 m, baited trap, 17 August 1991, J.K. Lowry & J.M. Poupin, RV Marara [FRP-55]; 48 specimens, AM P.42144; 4 specimens, AM P.42145, off Rapa, Austral Isles, French Polynesia, (27°35.5' S 144°15.8'W), 750 m, baited trap, 18 August 1991, J.K. Lowry & J.M. Poupin, RV Marara [FRP-64 & FRP-66].

Diagnostic description. Mandible molar setose with a triturating surface. Maxilla 2 inner plate slightly shorter than outer plate. Gnathopod 1 subchelate; coxa 1 large, about as long as coxa 2, subrectangular, anterior margin nearly straight; ischium not enlarged; propodus margins subparallel; palm transverse, slightly convex. Gnathopod 2 chelate; palm obtuse, margin excavate; dactylus with ‘setal basket’ on posterodistal margin. Pereopod 7 basis tapering distally. Epimeron 3 posteroventral corner narrowly rounded . Telson moderately cleft.

Remarks. Abyssorchomene gerulicorbis has a subrectangular first coxa with a nearly straight anterior margin similar to A. abyssorum and A. charcoti. Abyssorchomene gerulicorbis and A. abyssorum have subchelate first gnathopods (parachelate in A. charcoti). It is difficult to separate A. gerulicorbis from A. abyssorum and A. scotianensis. Abyssorchomene gerulicorbis and A. abyssorum both have subrectangular first coxae (subtly adzeshaped in A. scotianensis). The inner plate of maxilla 2 is significantly shorter than the outer plate in the A. abyssorum of Barnard & Ingram (1990), but not in the specimen of Stebbing (1888) or to a less extent the specimen of Birstein & Vinogradov (1990). The adze-shaped first coxa separated A. scotianensis separates form these two species but in other characters they are extremely similar.

Abyssorchomene gerulicorbis differs from A. chevreuxi mainly in the upper lip which is slightly produced and apically narrowly rounded (upper lip not produced in A. chevreuxi) and in A. gerulicorbis the dactylus of gnathopod 1 has a posterodistal ‘setal basket’ (absent in A. chevreuxi).

Distribution. North Atlantic Ocean: Porcupine, Iberian, Madeira, Cape Verde, and Guiana Abyssal Plains (Thurston 1990). North Pacific Ocean: Kuril-Kamchatka (Birstein & Vinogradov 1955); north of Hawaii (Shulenberger & Barnard 1976). South Pacific Ocean: Austral Isles (Lowry & Stoddart 1994); Kermadec Trench (Jamieson et al. 2011); east coast of Australia (this study). Indian Ocean: Crozet Plateau (Cousins et al. 2013).