Eastern Pacific Ghostshark

description

Comparative Material. Hydrolagus mccoskeri – 2 specimens. CAS 86558, holotype juvenile female, 381 mm TL, 211 mm BDL, southeast of San Cristobal Island, Galapagos (01 ° 5.981 ’ S 89 ° 12.235 ’ W), 296.24 m, collected by J. E. McCosker (CAS), R. Grant Gilmore (Harbor Branch Oceanographic Institution) and Bruce Robison (MBARI), 17 Nov. 1995 (JSL dive 3934); CAS 223971, paratype, juvenile female, 227 mm TL, 107 mm BDL, off Isla Española, Galapagos, (01 ° 5.981 ’ S, 89 ° 45.5 ’ W), 505.97 m, collected by J. E. McCosker (CAS), and John Ross (Smithsonian Magazine), 6 Jul. 1998 (JSL dive 3094). Hydrolagus alphus – 2 specimens. CAS 201902, holotype, adult male, 419 mm TL, 249 mm BDL, North end of Seymour Island, Galapagos (0 ° 21 ’ 42 ” S, 90 ° 15 ’ 0 ” W), 648 m, collected by J. E. McCosker (CAS) and Carole Baldwin (United States National Museum), 25 July 1998 (JSL dive 3113); CAS 86425, paratype, subadult female, 480 mm TL, 244 mm BDL, Fernandina Island, Galapagos (0 ° 14.461 ’ S 91 ° 26.535 ’ W – 0 ° 14.820 ’ S 91 ° 26.410 ’ W), 731.52 m, collected by J. E. McCosker (CAS), R. Grant Gilmore (HBOI) and Bruce Robison (MBARI), 17 Nov. 1995 (JSL dive 3958) Hydrolagus macrophthalmus – 4 speci

A new species of chimaera, Hydrolagus melanophasma sp. nov. (Chondrichthyes: Chimaeriformes: Chimaeridae), from the eastern North Pacific

description

Description. Morphometric measurements of the holotype and paratype are presented in Table 1; proportional measurements presented below are of the holotype followed by the paratype in parentheses. A medium to large bodied Hydrolagus with a blunt snout that slopes minimally from the orbit to snout tip; eyes moderate size, length 22.2 % (26.0 %) of head length. Snout-vent length is short, 60.1 % BDL (56.9 %), nearly equal to pelvic-caudal space, 57.9 % BDL (60.1 %). Pectoral-pelvic space, 29.8 % BDL (32.2 %), is one-half snout-vent length. Skin firm and robust, not deciduous as in some Hydrolagus (Didier 2002, Didier 2008). Pectoral fins large, triangular, anterior margin 40.9 % BDL (38.5 %), extends to or beyond pelvic fin insertion when laid against the body. Anterior margin of pelvic fins straight, length about one-half of pectoral fin anterior margin, 21.0 % BDL (19.5 %); pelvic fin posterior margin convex. H. melanophasma Holotype (male) Paratype (male) SIO 77 - 211 LACM 39805 - 1 Measurement % BDL % BDL H. melanophasma Holotype (male) Paratype (male) SIO 77 - 211 LACM 39805 - 1 Measurement % HDL % HDL HDL (mm) 170.0 158.0 ONC 8.2 8.8 LRC 3.8 4.1 LNC 26.0 28.0 IOA 14.9 16.1 OTM

A new species of chimaera, Hydrolagus melanophasma sp. nov. (Chondrichthyes: Chimaeriformes: Chimaeridae), from the eastern North Pacific

description

Hydrolagus colliei is the only Hydrolagus species, besides H. melanophasma, known to occur in the eastern North Pacific. The distribution of H. colliei is from southeastern Alaska to Baja California and the northern Gulf of California. Hydrolagus colliei is distinct from H. melanophasma in coloration, being uniformly dark brown to reddish-brown with numerous white spots on the head and trunk, a strongly indented second dorsal fin, a shorter second dorsal fin base length (57 – 72 % BDL vs. 77.3 – 81.1 % BDL), a longer distance from origin of the second dorsal fin to origin of pectoral fin (37 – 53 % BDL vs. 16.4 – 19.6 % BDL), and a longer snout-vent length (67 – 93 % BDL vs. 56.9 – 60.1 % BDL) (Didier and Rosenberger 2002). Hydrolagus melanophasma is known from southern California and Baja California with most records from the Gulf of California. Hydrolagus melanophasma is considered a deep-water species despite the shallow depth of the holotype collection. It typically occurs deeper than H. colliei, which is known to occur from surface waters in the northern part of its range to 971 m at the southern end of its range (Ebert 2003). Documented collections of H. melanophasma are as f

A new species of chimaera, Hydrolagus melanophasma sp. nov. (Chondrichthyes: Chimaeriformes: Chimaeridae), from the eastern North Pacific

description

Nontype Specimens: SIO 68 - 89 (4 specimens), 930 – 1200 mm TL, Northwest of Isla Angel de la Guarda, Mexico (29 ° 42.0 ’ N 113 ° 56.7 ’ W), 565 – 644 m, 18 January 1968, by otter trawl. SIO 65 - 435 (2 specimens), (30 ° 53.2 ’ N 118 ° 4.7 ’ W), 1155 m, 22 September 1965, by trap and setline. LACM 37753 - 1, (1 specimen), 900 mm TL, California, U. S. A. (32 ° 26.5 ’ N 119 ° 45 ’ W), 1400 m, September 1978, aboard the Califia.

A new species of chimaera, Hydrolagus melanophasma sp. nov. (Chondrichthyes: Chimaeriformes: Chimaeridae), from the eastern North Pacific