Hydrolagus matallanasi Soto & Vooren, 2004, sp. nov.
Creators: name: Jules M. R. Soto
name: Carolus M. Vooren
Publisher: name: Zenodo
Year: 2004
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Holocephali
Chimaeriformes
Chimaeridae
Hydrolagus
Hydrolagus matallanasi

description: Hydrolagus matallanasi sp. nov.
(striped rabbitfish / quimera-malhada)
Figures 1-4, Table 1
Holotype. MOVI 24303, mature male (296 mm PCL), 29º52.08’S, 047º48.39’W, 517 m, 20.7ºC surface temp., 6.9ºC bottom temp., off Santa Catarina, Brazil, #238, REVIZEE Program, 10 Sep. 2001, bottom trawl, RV “ Atlântico Sul”.
Paratypes. Twenty specimens: MOVI 24304 (277 mm TL) and MOVI 24305 (234 mm PCL), males, same haul as holotype; MOVI 24291 (331 mm PCL), MOVI 24292 (347 mm PCL), MOVI 24293 (296 mm PCL), and MOVI 24294 (268 mm PCL), females, 24º01.90’S, 042º38.80’W, 736 m, off Rio de Janeiro, Brazil, 11 Mar. 2002, #47, bottom trawl, FV “Nuevo Apenino”; MOVI 24295 (female 353 mm PCL), 23º47’10”S, 041º49’46”W, 518 m, off Rio de Janeiro, Brazil, #04, 16 Sep. 2001, bottom gillnet, FV “South Coast”; MOVI 24296 (male 302 mm PCL), and MOVI 24297 (female 280 mm PCL), 23º42.00’S, 042º07.05’W, 419 m, off Rio de Janeiro, Brazil, #63, 03 Dec. 2001, bottom trawl, FV “Nuevo Apenino”; MOVI 24298 (278 mm PCL), MOVI 24299 (270 mm PCL), MOVI 24300 (275 mm PCL), and MOVI 24301 (239 mm PCL), males, 23º44’19”S, 041º53’31”W, 416 m, off Rio de Janeiro, Brazil, #101, 26 Dec. 2001, bottom trawl, FV “Cipi”; MOVI 24302 (female 271 mm PCL), 30º17.90’S, 047º56.99’W, 449 m, 22.0ºC surface temp., 11.7ºC bottom temp., off Santa Catarina, Brazil, #240, REVIZEE Program, 10 Sep. 2001, bottom trawl, RV “ Atlântico Sul”; NUPEC 1782 (328 mm PCL), NUPEC 1783 (349 mm PCL), NUPEC 1784 (378 mm PCL), NUPEC 1785 (352 mm PCL), NUPEC 1786 (357 mm PCL), and NUPEC 1787 (351 mm PCL), females, 650-700 m, off southern Rio de Janeiro, Brazil, Mar. 2002, bottom trawl, commercial fishing vessel not identified.
Comparative material. H. alberti - USNM 153558, holotype (male 275 mm PCL) and USNM 153559, paratype (male 280 mm PCL), 558 m, 29º11’N, 086º52’W, off Pensacola, Florida; ISH 257/1981 (2 specimens), NSMT-P 40045, (male 435 mm PCL), 570- 620 m, off Suriname. H. mirabilis - ISH 1034/1982 (3), ISH 64/1965 (1), NSMT-P 40046 (female 253 mm PCL), NSMT-P 40634 (male 359 mm PCL), 875-920 m, off Suriname and French Guiana.
Diagnosis. This new species can be distinguished from its congeners by the following combination of characters: an irregular brown coloration with reticulations and spots over the body; ventral surface whitish, including pectoral bases; proximal margin of the second dorsal fin whitish; tooth plates striped and bicolor, yellowish and gray; length of dorsal fin spine equal to or a slightly greater than head length; pectoral fin notably long, its tip extending beyond posterior margin of pelvic fin base; upper margin of second dorsal fin notably concave at middle region of second dorsal fin base; minimum height of second dorsal fin less than half of maximum height (located at points anterior and posterior to middle region of fin); eye length slightly smaller than preorbital length.
Description. Body proportions of holotype and paratypes are given in Table 1. Drawing of the holotype in Figure 1. A small-bodied species, adult males measure from 296 to 302 mm PCL (n=8). Body tapering from head and trunk to a whip-like tail with long filament. Eye large, dorsolaterally situated, 2/3 of preorbital length. Lateral line canal curved ventrally at point slightly anterior to first dorsal fin spine. Pectoral fin long, its tip beyond insertion of pelvic fin when depressed, and more than 1.5 times head length. In vertical projection, first dorsal fin origin slightly posterior to anterior insertion of pectoral fins; dorsal-fin spine long, its length equal to or slightly greater than head length; upper margin of second dorsal fin notably concave at middle region of second dorsal fin base; second dorsal fin with minimum height less than half of its maximum height (measured at points anterior and posterior to middle region of fin). Caudal filament elongate, longer than distance from tip of snout to insertion of pelvic fin. Anal fin absent. The lateral line canals of the head have the same pattern as the H. mirabilis group: the preopercular (POP) and oral (O) lateral line canals branch from the infraorbital canal (IO) (Fig. 2), whereas in the H. colliei group the POP and O canals are not fused. Claspers bifid, divided for only distal 1/ 3 of length (Fig. 3). Brownish reticulations and spots covering the body; ventral surface brownish white, including pectoral fin bases (Fig. 1); tooth plates striped and bicolor, yellowish and gray (Fig. 4).
Distribution. Twenty-one specimens were collected at seven stations off the states of Santa Catarina (2 sta., 4 specimens) and Rio de Janeiro (5 sta., 17 specimens), southern Brazil, between 23º42'S and 30º18'S, 416-736 m depth (Fig. 5).
Etymology. Named in honor of Dr. Jesús Matallanas Garcia, in recognition of his extensive work and tireless dedication to ichthyology.
Biological and ecological notes. Males range in size from 234 to 302 mm PCL (n=8) and mature at or around 296 mm PCL. Females range from 268 to 378 mm PCL (n=13). Gorgonians, hard corals, tube sponges, crinoids, and ophiuroids were taken near collecting sites of H. matallanasi providing evidence that this species inhabits deep-reefs on the continental slope, usually deeper than 400 m. It also shares this habitat with the sharks Heptranchias perlo, Scyliorhinus haeckelii, Galeus mincaronei, Schroederichthys saurisqualus, Squalus sp., and the skate Gurgesiella dorsalifera.
Comparisons. Hydrolagus matallanasi and H. mirabilis share an indented second dorsal fin, but are easily distinguished by: colour pattern (reticulations and spots covering the body dorsolaterally vs body uniform pale brown); ventral pectoral-fin bases (brownish white vs pale brown); eye length (about 2/3 of preorbital length vs nearly equal to preorbital length); tooth plates coloration (striped and bicolor, yellowish and gray vs yellowish); and dorsal-spine length (equal to or a slightly longer than head length vs 4/5 of head length). Another Atlantic species, H. alberti, is not similar to the new species, as its upper second dorsal fin margin is straight while in H. matallanasi it is notably concave near the middle of the second dorsal fin base. Coloration also differs among these two species, as H. alberti is pale brown with no reticulations or spots.
Key to the western Atlantic Hydrolagus species
[Modified from Bigelow and Schroeder (1953) and Didier (2004)]
1a. Upper margin of second dorsal fin straight..................................................... H. alberti
1b. Upper margin of second dorsal fin notably concave at middle region of second dorsal fin base..........................................................................................................................2
2a. Body pale brown, without reticulations and spots; ventral base of pectoral fin darkish brown; eye length nearly equal to preorbital length; dorsal spine length 4/5 of head length; pelvic claspers in males divided for nearly 1/2 their length............ H. mirabilis
2b. Brown coloration with reticulations and spots covering dorsoventrally the body; ventral base of pectoral fin whitish; eye length about 2/3 of preorbital length; dorsal spine length equal to or slightly longer than head length; pelvic claspers in males divided for nearly 1/3 their length ................................................................ H. matallanasi sp. nov.
description: Published as part of Jules M. R. Soto & Carolus M. Vooren, 2004, Hydrolagus matallanasi sp. nov. (Holocephali, Chimaeridae) a new species of rabbitfish from southern Brazil., pp. 1-10 in Zootaxa 687 on pages 3-8