Gymnotocinclus anosteos Carvalho, Lehmann A. & Reis 2008

Gymnotocinclus is distinguished from all other hypoptopomatine genera by the following uniquely derived features: extreme reduction of body dermal plates; absence of the lateral connecting bone; absence of bifid hemal spines on the abdominal vertebrae posterior to the first anal-fin proximal radial; and odontode tipson last dermal plates on the caudal peduncle dorsally or anteriorly curved. Gymnotocinclus is also distinguishedby a number of non-exclusive traits: maxillary barbel adnateto the lower lip; lateral ethmoid almost completely encapsulating the nasal organ; ventral margin of preopercle straight, not deflected medially; pectoral girdle exposed andsupporting odontodes only in a restricted lateral area near base of pectoral fin; and absence of a pectoral-fin slit (Ref. 79020).

Gymnotocinclus anosteos is a species of armored catfish (Loricariidae) endemic to Brazil, where it is found in the Tocantinzinho River in the Tocantins River basin. This species grows to a length of 4.4 centimetres (1.7 in) SL.

The genus Gymnotocinclus is unusual among the Loricariidae due to its extremely reduced armor plates that are characteristic of the family, giving the fish a relatively naked body. This fish probably has a basal position in the subfamily Hypoptopomatinae.