The morphometric model used in the present study
demonstrates
unambiguously that the Linnean type series of
H. plecostomus is heterogeneous and comprises two distinct
species: H. plecostomus and H. watwata. The watwata group
corresponded to different populations of the nominal species,
H. watwata, which occurs in brackish waters along the
Guianese coast. This species displayed significant morphometric
structures as attested by the high statistical support
observed. Hypostomus watwata is mostly characterized by
its slender appearance with long caudal peduncle. In addition
this species possesses numerous platelets just bordering
the posterior portion of the supraoccipital and the pteroticsupracleithrum.
This feature is perfectly visible on both possible
paralectotypes of H. plecostomus but absent on the lectotype.