Hydrolagus matallanasi sp. nov. (Holocephali, Chimaeridae) a new species of rabbitfish from southern Brazil.
Jules M. R. Soto
Carolus M. Vooren
Zootaxa
2004
687
1
10
3N7F3
urn:lsid:zoobank.org:act:2AB9A3E3-3848-4839-8F5E-97E97ABF29CD
Holocephali
Chimaeridae
Hydrolagus
CoL
Animalia
Hydrolagus matallanasi Soto & Vooren 2004:3
Chimaeriformes
3
Chordata
species
matallanasi
Figures 1-4, Table 1
Comparative material. H. alberti- USNM153558, holotype (male 275 mm PCL) and USNM153559, 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. mirabilisgroup: the preopercular (POP) and oral (O) lateral line canals branch from the infraorbital canal (IO) (Fig. 2), whereas in the H. colliei groupthe 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'Sand 30º18'S, 416-736 m depth (Fig. 5).
Etymology. Named in honor of Dr. JesusMatallanas 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. matallanasiproviding 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, Squalussp., and the skate Gurgesiella dorsalifera.
Comparisons. Hydrolagus matallanasiand H. mirabilisshare 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. matallanasiit is notably concave near the middle of the second dorsal fin base. Coloration also differs among these two species, as H. albertiis pale brown with no reticulations or spots.
Key to the western Atlantic Hydrolagusspecies [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.
923932657
2001-09-10
bottom trawl
MOVI
RV “ Atlantico Sul”
Brazil
-29.868
517 m, off Santa Catarina
-47.8065
MOVI 24303
Holotype
923932664
2001-09-10
bottom trawl
MOVI
RV “ Atlantico Sul”
Brazil
-29.868
517 m, off Santa Catarina
-47.8065
MOVI 24304, MOVI 24305
Paratypes
923932661
2002-03-11
bottom trawl
MOVI
FV “Nuevo Apenino”
Brazil
-24.031666
736 m, off Rio de Janeiro
-42.646667
MOVI 24291, MOVI 24292, MOVI 24293, MOVI 24294
Paratypes
923932660
2001-09-16
bottom gillnet
MOVI
FV “South Coast”
Brazil
-23.78611
518 m, off Rio de Janeiro
-41.829445
MOVI 24295
Paratype
923932662
2001-12-03
bottom trawl
MOVI
FV “Nuevo Apenino”
Brazil
-23.7
419 m, off Rio de Janeiro
-42.1175
MOVI 24296, MOVI 24297
Paratypes
923932658
2001-12-26
bottom trawl
MOVI
FV “Cipi”
Brazil
-23.738611
416 m, off Rio de Janeiro
-41.891945
MOVI 24298, MOVI 24299, MOVI 24300, MOVI 24301
Paratypes
923932659
2001-09-10
bottom trawl
MOVI
RV “ Atlantico Sul”
Brazil
-30.298334
449 m, off Santa Catarina
-47.949833
MOVI 24302
Paratype
923932663
2002-03
bottom trawl
NUPEC
commercial fishing vessel not identified
Brazil
650-700 m, off southern Rio de Janeiro
NUPEC 1782, NUPEC 1783, NUPEC 1784, NUPEC 1785, NUPEC 1786, NUPEC 1787
Paratypes