Opipeuter xestus, new genus, new species, is placed in Group II of the family Teiidae (Squamata, Reptilia) because it has five clawed digits on all four feet, the nasals separated by a frontonasal, and the nostril pierced in the middle of the nasal scale. It differs from other known members of Group II in having the combination of total absence of keeled scales and a relatively enormous transparent disc in the lower eyelid. The arrangement of enlarged calcareous spines in the hemipenis distinguishes the new taxon; enlarged spines are present on the basal part of the median welt, and in a row on each side of the sulcus spermaticus. The affinities of the new taxon are not with Prionodactylus, although most specimens have been identified as Prionodactylus bolivianus; the affinities may be with Euspondylus, but are not clearly so. Known specimens come from several localities between 1000 and 3000 m above sea level in the headwaters of the Río Chapare on the eastern Andean slopes of central Bolivia.