Salamanders of the Genus Bolitoglossa from the Sierra Madre del Sur of Southern Mexico

Abstract

The Sierra Madre del Sur of Oaxaca and Guerrero, along the west coast of Mexico, marks the northwestern limits of the genus Bolitoglossa. The three species known from these mountains comprise the macrinii group, which differs from all other Bolitoglossa beta by lacking mental gland clusters in adult males, and in having extremely weak premaxillary bones that fre- quently have incomplete frontal processes. Bolitoglossa macrinii and B. riletti occur in Oaxaca, and B. hermosa, here described, has recently been found in Guerrero. These species can be distinguished by differences in color pattern and amount of foot webbing. The three species are also well differ- entiated on the basis of morphometric and electrophoretic differences. Over half of the world's known species of salamanders are tropical plethodontids in the tribe Bolitoglossi- ni. As recently as fifty years ago, only 30 tropical species were recognized. To- day over 160 have been described. The largest genus in the Bolitoglossini is Bolitoglossa with about 75 species. Its members span the New World tropics from near the Tropic of Cancer in the north to the Tropic of Capricorn in the south. The Sierra Madre del Sur, locat- ed in the states of Oaxaca and Guerrero, Mexico, apparently represent the northwestern limits of the genus along the west coast of Mexico. The drainage of this mountain range is west of the Continental Divide and the range ex- tends from the Isthmus of Tehuantepec in the east-southeast to the mouth of the Rio Balsas in the west-northwest.