Four species [P. pachyurus Tschudi, P. bolivianus Werner, P. guentheri (Boettger), P. ventrimaculatus Boulenger] occur in Bolivia and Peru. The first three (the P. pachyurus group) have an undivided translucent disc in the lower eyelid, a median occipital, two or three supraoculars, and squarish pregulars not forming chevrons. This group resembles P. striatus (Peters) in the last character, but differs from it in the first three. P. pachyurus (17 examined) and P. bolivianus (158) occur at about 2500-3800 m above sea level on the eastern Andean slopes, the former in central Peru, the latter in southern Peru and northern Bolivia. P. guentheri (30) occurs parapatrically at lower elevations (1000-2516 m). Although the hemipenes of P. bolivianus and P. guentheri resemble each other rather than that of P. pachyurus, in most respects P. bolivianus and P. pachyurus are more similar to each other. Specimens of P. bolivianus from the upper reaches of the Río Urubamba differ from those from the lower Rio Urubamba valley in size, ventral coloration, presence of a loreal, and number of anterior supralabials. A small sample from Cuzco resembles those from the lower Río Urubamba valley in absence of a loreal and in femoral pore number, but resembles specimens from the upper valley in size and some aspects of coloration. P. ventrimaculatus (2; northern Peru, 2200-2700 m) has a divided eye disc, an enormous first superciliary resembling a supraocular, a small first supraocular touching the palpebrals, and a smaller second supraocular separated from the palpebrals by a superciliary. The relationships of P. ventrimaculatus may be with P. striatus. The name P. petersi (Boettger) is placed in the synonymy of P. unicolor (Gray). P. bolivianus is removed from the synonymy of P. guentheri and is used for the taxon formerly called P. petersi; P. lacertus (Stejneger), P. longicaudatus Andersson, and P. obesus Barbour and Noble are synonyms. P. ocellifer (Boulenger) and P. anomalus (Barbour and Noble) are placed in the synonymy of P. guentheri.