Leptodactylid frogs of the genus Eleutherodactylus in the Andes of northern Ecuador and adjacent Colombia

INTRODUCTION Although a prominent component of the fauna of most mesic environments in northwestern South America, the genus Eleutherodoctylus is poorly represented in the pajonales (=subparamos) and paramos of southern Colombia and northern Ecuador. Field work in these highland areas by the late James A. Peters and his associates and by indi-viduals associated with the Museum of Natural Histoiy of the University of Kansas has yielded adequate altitudinal and geographic samples of eleuthero-dactyline frogs to permit ecological and systematic summaries of the frogs of this region. This study is the fourth in a series describing the Eleutherodactylus of Ecuador. The first (Lynch, 1979) treated the fauna of southern Andean Ecuador, the second (Lynch, 1980) sum-marized the fauna of the western Ama-zonian Basin, and the third (Lynch and Duellman, 1980) treated those faunas on the Amazonian slopes of the Andes in Ecuador. The principal area under discussion extends, from the Nudo de Pasto in southern Colombia south to the Desierto de Palmira in southern Provincia Chim-borazo of Ecuador (about 2° S). Pajo-nale and paramo habitats within this area originally ranged in altitude from 3200 to 4800 m (Acosta-Solis, 1968) but now extend to lower altitudes where human activity has removed the high Andean forests (ceja andina) or replaced them with Eucalyptus. Seven species of Eleutherodactylus and one species of Phrynopus are restricted to or primarily distributed within the pajonales and paramos. Six other species [Eleuthero-dactylus chloronotus Lynch, E. leoni Lynch, E. supernatis Lynch, E. trepi-dotus Lynch, E. lo-nigrum (Boettger), and Phrynopus peraccai Lynch] are spe-cies of the ceja andina and are occasion-ally found in those pajonales that abut the high cloud forests. Most Andean Eleutherodactylus have restricted distributions. Three of the species found in the Andes of northern Ecuador are exceptions. Eleutherodac-tylus curtipcs (Boulenger) ranges from the Colombia-Ecuador border (ca °1 N) south to the Desierto de Palmira (ca 2° S ) over an altitudinal range of from 2750 m to at least 4400 m. Its northern limit corresponds in an interesting and sug-gestive way with the political boundary of Colombia and Ecuador but in spite of the efforts of several collectors the species has eluded discovery in Colom-bia. The collectors instead find E. huckleyi (Boulenger) there, a close rel-ative. Eleutherodactylus huckleyi is also found in extreme northern Ecuador but is distributed primarily in Colombia, in the Cordillera Central (to ca 4° N). The third widely distributed species, E. uni-strigatus (Giinther), generally occurs at lower elevations and in somewhat more xeric situations than E. huckleyi and E. curtipes. Eleutherodactylus unistrigatus occurs from the Nudo de Pasto in south-ern Colombia south primarily through interandean Ecuador to the vicinity of Riobamba. The general concordance of the southern termini of E. curtipes and E. unistrigatus coupled with the pres-ence of a distinctive suite of eleuthero-dactylines south of the Desierto de Pa-mira led Lynch ( 1972a ) to postulate a faunal break. Lynch (1972a) suggested that E. huckleyi and E. curtipes were synony-mous. That view is contradicted, how-ever, by the sympatric occurrence of the two frogs over much of Provincia Carchi, Ecuador. The other four species of Eleuthero-dactylus and the only species of Phryn-opus (P. hrunneus Lynch) found in high altitude grasslands in northern Ecuador have small distribution areas. These Eleutherodactylus are E. orcesi Lynch, E. thymelemis Lynch, and two species named below.