QH 1 B4X NH No. 26, pp. 325-346 12 October 1976 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON AMMOCRYPTOCHARAX ELEGANS, A NEW GENUS AND SPECIES OF RIFFLE-INHABITING /U GHARACOID FISH (TELEOSTEI: CHARAGIDAE) i cr FROM SOUTH AMERICA "^ By Stanley H. Weitzman and Robert H. Kanazawa 3C _^ Department of Vertebrate Zoology, National Museum \ of Natural History, Washington, D.C. 20560 "^^ The new genus and species, Ammocryptocharax elegans, described here first came to our attention in 1970 in a small collection of fishes received from the Brazilian-Bolivian bor-der region. Since that time we have acquired additional collections from Brazil, Colombia, and Venezuela. The elon-gate body and head, and the ventral mouth superficially re-semble these features in the sand darters of the North Amer-ican genus Ammocrypta Jordan. This again attests to the remarkably divergent evolutionary radiation of South Amer-ican characoids (see Weitzman, 1962). Ammocryptocharax elegans has been described in life as being bright "grass green" and occurring among water plants in small riffles where it was taken in the Caiio Muco, Colombia (J. Thomer-son, pers. comm.). It is not known if the fish burrows in sand or dives in among rocks and stones although its slender body shape, ventral mouth, and conic snout would suggest such ability. The new genus described here belongs to the Chara-cidiinae, a group of primarily South American characoid fishes (one species, Characidium marshi Breder, is known from the Tuira basin in Panama) of uncertain family affini-ties and here tentatively assigned to the Characidae. Gery (1971) recognized the Characidiinae to be of family rank CD CP :'".) :^; — ! —•• \3 zn o C/2 _Jk s_^ X) s ^ en Oi.; 26— Proc. Biol. Soc. Wash., Vol. 89, 1976 (325)
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