Frog Genus Atelopus in Ecuador (Anura: Bufonidae): Smithsonian Contributions to Zoology, Number 145

摘要

The genus Atelopus is represented in Ecuador by 15 species, of which 6 are here described as new taxa. A key for identification, descriptions, and figures are presented for all species, and a detailed analysis of variation in proportions attempts to quantify certain subjective characteristics used by earlier frog systematists. The genus includes two nonphylogenetic groups of species, the first, with slender bodies and long limbs, usually found in the lowlands and lower mountain slopes, and the second, with stocky bodies and short limbs, usually found at higher altitudes in the Andes. The species appear to be highly responsive to environmental changes, and successful invasions of the mountains by the lowland species are accompanied by differentiation, evolution, and speciation. Invasions are likely to be along major river drainages. The invaders are effectively isolated from adjacent drainages by factors such as the highly dissected terrain, rain shadow, barren areas, and so on. High altitude species are restricted in lateral distribution, but often have considerable altitudinal range, while low altitude species have wide latitudinal range, but are restricted altitudinally. The mountains in Ecuador are 'continental islands,' showing diversity and adaptive radiation similar to that of the Hawaiian Islands, with the major difference that the Andes are not dependent upon 'waifs' or 'drifters' for invaders, but are constantly supplied by the abundant life of the surrounding tropical forests.