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Fishes living in deepsea thermal vents in the tropical eastern Pacific, with descriptions of a new genus and two new species of eelpouts (Zoarcidae)

1986; Volume: 21; Linguagem: Inglês

10.5962/bhl.part.24575

0080-5947

Richard H. Rosenblatt, Daniel M. Cohen,

Ichthyology and Marine Biology

A new genus and two new species of zoarcid fishes are described from deep sea hydrothermal vent systems in the eastern Pacific.The new genus Thermarces is distinguished from other zoarcids by reduction of suborbital bones to one or two, unossified pectoral radials, and lack of fourth infrapharyngobranchial bone, postcleithrum, scales and pelvic fins.One species of the genus has been taken at 21''N, 109°W, and near the Galapagos Islands, the other at 12°48'N, 104°W.The new species are diagnosed and described.The otoliths examined show clear growth rings.The objectives of this paper are to distinguish so far as possible the various fishes known to hve in warm water vented from deepsea springs in the tropical eastern Pacific.Two species of eelpouts appear to be heretofore unknown, and we describe them here.One so-called vent fish that has been observed and photographed from the submersible ALVIN in and near vents along the Galapagos Rift was referred by Cohen and Haedrich (1983) to the genus Diplacanthopoma of the ophidiiform family Bythitidae (Cohen and Nielsen 1978).Photographs of the same or a similar form taken by Harmon Craig, Scripps Institution of Oceanography (SIO) from ALVIN at a vent system at 10°57'N, 103°41'W have been seen by us, and Robert R. Hessler, SIO, has seen small individuals at 13°N from CYAN A. No bythitid fish has yet been seen at 2rN despite extensive observations.As of this writing specimens have not been captured, and the species is not further discussed in the present paper.The Zoarcidae, or eelpout family, also includes species of vent-associated fishes.At the Galapagos Rift vent area, eelpouts are cryptic and have been questionably identified from ALVIN only twice; however, two species are common in time-lapse photographs (Cohen and Haedrich 1983).Two specimens have been captured, one a relatively large, light-brown individual taken in a trap; the other, a smaller, pale fish, was washed from ALVIN after the submersible surfaced.The two specimens have very similar counts and head pore patterns.At 21°N a pale zoarcid was observed to be common in warm water.Several specimens were captured incidentally, and enzyme activities were described by Hand and Somcro (1983).We have also examined two pale specimens trapped among pogonophorans by a French expedition working at vents near 13°N, where eelpouts were common.Recently a sulfide-rich area with a community having many features of the Pacific vent communities has been discovered off the Florida escarpment (Paull et al. 1984).Color photographs seen by us show an elongate, pale fish on the bottom, certainly a zoarcid, and with a considerable general resemblance to our new genus.However, neither specimens nor close-up pictures are available.