Spectracanthicus murinus is a species of suckermouth armored catfish endemic to Brazil where it is found in the Tapajós River basin. This species grows to a length of 6.4 centimetres (2.5 in) SL. S. murinus appears to be unique in the sub-family Ancistrinae in that it has lost many of the traits that describe this group, such as evertible cheek plates and modified opercle.