PROC. BIOL. SOC. WASH. 103(3), 1990, pp. 550-557 CYPHOCHARAX PANTOSTICTOS, A NEW SPECIES (PISCES: OSTARIOPHYSI: CHARACIFORMES: CURIMATIDAE) FROM THE WESTERN PORTIONS OF THE AMAZON BASIN Richard P. Van and Ramiro Barriga S. Abstract. — Cyphochar ax pantostictos, a species of curimatid characiform with a distinctive pattern of dark spots arranged in longitudinal series along the sides of the body, is described as new from the Rio Napo, Rio Putumayo, Rio Ucayali, and Rio Nanay in Ecuador and northern Peru. Cyphocharax multi-lineatus (Myers), the only other species in that questionably monophyletic genus with a similar pigmentation pattern has dark wavy horizontal lines, rather than discrete spots arranged in horizontal patterns. The dark body pigmentation in the two species also differs in its relative position on the scales. The pigmen-tation pattern and overall external appearance of C. pantostictos are nearly identical to that of Steindachnerina fasciata (Vari & Gery) a species endemic to the upper Rio Madeira system in Brazil. The two species can be readily distinguished on the basis of a series of meristic and morphometric features, and in differences in the portion of buccopharyngeal complex on the roof of the oral cavity. A series of polarized characters indicate furthermore that the two species are not closely related. The myriad drainage systems, range of stream gradients, and complexity of aquatic habitats found in the drainage basins of the western portions of the Amazon basin are reflected in the remarkable diversity of the fish fauna in that region (Ortega & Vari 1986, Stewart et al. 1987). This region is also one of the areas of greatest diversity for the fam-ily Curimatidae, involving both species widely distributed within the Amazon basin (e.g., Curimata aspera Giinther (Vari 1988: fig.8) and C vittata Kner (Vari 1989b:42)), or ranging north and south of that system into the Rio Orinoco or Rio de La Plata systems (e.g., Steindachnerina guentheri (Eigenmann 8l Eigenmann) (Vari 1990)). Other curimatids in this area of high species diversity have much more restricted ranges (e.g., Steindachnerina quasirnodoi Vari & Vari (see Vari «fe Vari 1989:477)) and are known only to occur in the region that Kul-lander (1986:40) termed the "Western Am-azonian endemic area" based on distribu-tional data from various neotropical genera of the perciform family Cichlidae. In the course of investigations of the fish fauna of eastern Ecuador and northern Peru we in-dependently collected a distinctive species of curimatid with an unusual pigmentation pattern consisting of seven or eight longi-tudinal series of dark spots along the sides of the body. This material first appeared to represent a major extension in the known distribution of Curimata fasciata which Vari 8c Gery (1985) described from the Rio Ma-deira system in Brazil, a considerable dis-tance southeast of the region from which the Ecuadorian and Peruvian specimens originated. More recently Vari (1989a:ta-bles 2, 3), in an analysis of intrafamilial phy-logenetic relationships, restricted Curimata to a single lineage within the family and vQdiSS\gnQ6.fasciata to Steindachnerina Fow-ler (1906) on the basis of a series of derived
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