PROC. BIOL. SOC. WASH. 93(4), 1980, pp. 887-913 THE RELATIONSHIPS OF THE SOUTH AMERICAN PYGMY CHARACOID FISHES OF THE GENUS ELACHOCHARAX, WITH A REDESCRIPTION OF ELACHOCHARAX JUNKI (TELEOSTEI: CHARACIDAE) Stanley H. Weitzman and J. Gery Abstract. — Elachocharax junki (Gery), previously known only from the holotype, is redescribed on the basis of four additional specimens from the Rio Madeira basin and one from a tributary of the Rio Negro, Amazonas, Brazil. This species, originally described as Geisleria junki and placed in a monotypic subfamily, Geisleriinae, is here considered to be a species of Elachocharax of the characid subfamily Characidiinae. Elachocharax con-sists of three species, E. pulcher, E. geryi, and E. junki. Their relationships are discussed and a key is provided for their identification. The relationships of Elachocharax to the other genera of the Characidiinae is treated. The Geisleriinae and Elachocharacinae of Gery (1971) are rejected and placed as synonyms of the Characidiinae. The first known pygmy characoid related to Characidium Reinhardt and Jobertina Boulenger but having a very long dorsal-fin base with 17 to 20 rather than 10 to 14 dorsal-fin rays was Elachocharax pulcher Myers (1927) from the central region of the Rio Orinoco in Venezuela. In recent years, further collecting in the Amazon basin has resulted in the description of additional nominal species of Elachocharax. Elachocharax georgiae Gery (1965) was shown by Weitzman and Kanazawa (1978) to be a synonym of E. pulcher but two additional valid species have been described. Gery (1971) established a new genus and species, Geisleria junki (here placed in Elach-ocharax), from the Rio Novo in an area about 45 km east of Porto Velho in the basin of the Rio Madeira, Brazil. Weitzman and Kanazawa (1978) described a new species, Elachocharax geryi, from the middle of the Am-azon basin near Manaus, Brazil, and from Cano Muco, an upper tributary of the Rio Orinoco in Colombia. They further reported the extension of the known range of Elachocharax pulcher from the mid Rio Orinoco basin to an area covering much of the central Amazon basin. Gery (1971) assigned Geisleria junki to a new subfamily, Geisleriinae, based on its apparent possession of two rows of premaxillary teeth, pre-sumed absence of ectopterygoid teeth, the presence of what appeared to be maxillary teeth, a supposed absence of "suborbital" bones, and absence of
The relationships of the South American pygmy characoid fishes of the genus Elachocharax, with a redescription of Elachocharax junki (Teleostei: Characidae)
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