Summary
This study aimed to catalog the reptile species of the Sinos River Basin based on records from scientific collections and data collected in the field. We recorded 65 species, including 46 snakes, nine lizards, five turtles, four amphisbaenians, and one alligator. Snakes comprised the majority of the recorded specimens (91.3%), and the three most representative species are venomous and of medical importance. The most urban region of the basin (plain) has the highest number of records. This fact may be a reflection of the high human population density in this region, which would have favored the finding of specimens and their sending to scientific collections and research centers. It is worth mentioning that most of the species with few specimens in the collections are also rarely observed in nature, such as Clelia hussani and Urostrophus vautieri . This observation makes it possible that these populations are small or in decline.