On the anatomy and function of the cephalic structures in Phractura (Siluriformes : Amphiliidae), with comments on some striking homoplasies occurring between the Doumeinae and some loricaroid catfishes

The morphology and function of the cephalic structures related to the feedi ng mechanism movements of the mouth, suspensorium, opercular series, hyoid arch, maxillary barbels and mandibular barbels - was studied in two catfish species of the genus Phractura (Amphiliidae: Doumeinae), P. intermedia and P. brevicauda. For comparison, other species of the family Amphiliidae, as well as a large number of other catfishes, were also studied. The morpho-f unctional analysis pointed out that Phractura, as well as the other doumein s, present several unusual morphological modifications, which are very like ly related to two main functional specialisations: the ability to attach th e body to the substrate with an oral sucker, and the ability to scrape this substrate. The comparison with other siluriforms revealed an impressive nu mber of morpho-functional homoplasies occurring between the African doumein s and the South-American callichthyids, scoloplacids, astroblepids and lori cariids.