Lithogenes is the only genus within the subfamily Lithogeneinae. This genus and subfamily, the most basal group in Loricariidae, is the sister group to the rest of the family.[1] Relative to an undescribed species of Lithogeneinae, L. valencia has sister group relationship to L. villosus.[2]
As members of the family Loricariidae, all Lithogenes species have a suckermouth. However, unlike most loricariids, species of the genus Lithogenes possess armor plating only on the latter half of the body. Their eyes are small and their bodies flattened.[2][1]
L. villosus originates from the Essequibo River drainage of the Guiana Shield.[4] An undescribed species of Lithogenes is known from the Orinoco basin of the Guiana Shield.[2]L. valencia has only been known from six specimens collected in the 1970s from tributaries of the Lake Valencia in northern Venezuela; however, this area has since been polluted and this species possibly is now extinct.[2]
L. villosus lives in habitats dominated by rapids over bedrock, and L. valencia likely does, as well.[2][1]
