About Achondrostoma oligolepis (Robalo, Doadrio, Almada & Kottelat, 2005)
Achondrostoma oligolepis can be distinguished from other species in the Achondrostoma genus by several morphological traits. It has 30 to 38 scales along its lateral line, 3 or 4 scale rows between the lateral line and the origin of the pelvic fin, and 11 or 12 rows of scales around its caudal peduncle. Its eye diameter is smaller than the length of its rounded, obtuse snout, and the ventral profile of its head forms a marked angle at the articulation of the lower jaw. This species, commonly called ruivaco, reaches a maximum total length of 25 cm (9.8 in), with a more typical total length of 15 cm (5.9 in). This fish is endemic to Portugal. Its range extends from the Âncora River system south to the Arnoia and Real rivers; both of these rivers drain into the Óbidos coastal lagoon system located north of Lisbon. The ruivaco is a habitat generalist that lives in slow-moving, low-lying rivers and streams that contain aquatic vegetation and have sand or gravel substrates.
