The 12 recognized species of the genus Homonota are geographically restricted to central and southern South America in Argentina, Brazil, Uruguay, Bolivia, and Paraguay. The phylogenetic relationships within the genus are well known where three groups are identified, each of them containing four species: the whitii group (Homonota darwinii, H. williamsii, H. whitii, and H. andicola), the borellii group (H. borellii, H. taragui, H. rupicola, and H. uruguayensis) and the horrida group (H. horrida, H. underwoodi, H. septentrionalis, and H. marthae). During fieldwork in Paraguay, we found a specimen of Homonota with unique morphological and geographical traits. Thus, we performed a comparative morphological analysis against specimens housed in different Paraguayan collections. Additionally, we performed a DNA analysis of our specimen to assess its relationships within the genus. Results suggest that this specimen represents a new species of the Homonota horrida group based on molecular and morphological evidence. The new species is characterized by a robust body, 10 longitudinal rows of strongly keeled scales separated by one or two granular scales, square-shaped mental scales, small postmental scales, one or two rows of rectangular scales in the upper eye scales, rostral scale divided, edge of auditory meatus serrated posteriorly, and black and brown background coloration with one white vertebral line and seven white transverse bands. The new species is restricted to Paraguarí Department, characterized by herbaceous grasslands with rocky outcrops.