^ ^ MCZ LIBRARY B R E.y.iLiO R A usemm of Comparative Zoology UlNii ^ / ^-^ US ISSN 0006-9698 Cambridge, Mass. 25 March 1991 Number 493 NEW COLOSTETHUS (AMPHIBIA, DENDROBATIDAE) FROM SOUTH AMERICA Juan A. Rivero' Abstract. Six new species of Colostethus are described from South America: C. mittermeieri, C. idiomelus, and C poecilonotus from Peru; C. maculosus and C. paradoxus from Ecuador; and C . faciopunctulatus from Colombia. C. maculosus and C. faciopunctulatus belong to group VI (Rivero and Sema, 1988), C. mitter-meieri and C. idiomelus to group I, C. poecilonotus belongs to group IX, and C paradoxus to group IV. The relationship of the various species is discussed. C poecilonotus is the first member of group IX described from Peru, while C. paradoxus is the second member of group IV known from Ecuador. Group IV only extends south to the latitude of Quevedo in northwestern Ecuador. C paradoxus extends the range of the group to southern Ecuador. However, the possibility that the dilated third finger, which characterizes male members of group IV, may have arisen indepen-dently on more than one occasion is discussed. INTRODUCTION Examination of the Colostethus collection at the Museum of Comparative Zoology revealed a number of undescribed species from Peru, Ecuador, and Colombia. From these undescribed spe-cies a great deal is learned regarding their mutual relationships and the delimitation of the groups the genus has been divided into (Rivero, 1988). All the described species are well characterized and one of them is quite unique, so unique indeed that it cannot easily be assigned to any of the known groups of Colostethus. Yet, most of the groups, as originally suggested (Rivero, 1988), seem to have withstood Biology Department, University of Puerto Rico, Mayagiiez, Puerto Rico 00708.