Juveniles of the newly described species exhibit bright red tails on both the top and bottom sections, while adults show red coloration only on the bottom halves of their forked tails.

Researchers describe the type locality of Aphanotorulus rubrocauda: “The new species was found in fast-running waters of tributaries of the rio Aripuanã basin.  The rio Aripuanã is a dark-colored water river, poor in sediments, having cataracts, large boulders and a rocky bottom.”

The new pleco species is described in Neotropical Ichthyology.