Postotic laterosensory canal and
pterotic branch homology in catfishes.
A phylogenetic analysis of Hemibrycon genus determined its monophyly based on four synapomorpies: presence ectopterygoids with widened ventral anterior projection, four to six times wider than posterior part; a red spot present in life on ventral margin of caudal peduncle; a postero-ventral projection on the
pterotic and first infraorbitals gradually decreasing in width from posterior tip and located near posterior part of antorbital (Arcila Mesa 2008).
Prootic and/or
pterotic bulla lodging diverticulum of swimbladder.
Most of the bones (supraoccipital, epitotic,
pterotic, opisthotic, parietal, etc.) that compose the posterior part of the neurocranium are crushed beyond recognition.
Epiotic large, bearing crest for attachment of epaxial musculature (lesser crests also occurring on supraoccipital, exoccipital and
pterotic).
Frontal, parietal,
pterotic and supratemporal much cavernous resembling a bee-hive in general appearance.
Pterotic with 1-8 short, variably developed, more or less pointed projections from posterior margin.
1) constitutes, together with the
pterotic, a well-developed, deep articulatory facet for the hyomandibulo-metapterygoid.
The angles at which the
pterotic and preopercular spines protrude from the body have also been useful in identifying IndoPacific specimens (Ueyanagi, 1974a).
The following two features could constitute Pangasiidae autapomorphies: 1) presence of prominent crest on the dorso-lateral surfaces of both the hyomandibulo-metapterygoid and the ento-ectopterygoid; 2) presence of a large, circular foramen between the anterodorsomedial surface of the extrascapular, the dorsomesial surface of the
pterotic and the dorsolateral surface of the parieto-supraoccipital.
The nasal,
pterotic, and 4th superior infraorbital first appeared at 10.8 mm.