The quadrate-metapterygoid fenestra of otophysan fishes, its development and homology

We compare the ontogeny of hyopalatine arch in representatives Otophysi to shed light on homology so-called quadrate-metapterygoid fenestra, QMF. Described initially as a character characiforms (tetras and allies), presence QMF has also been reported for cobitid loaches handful cyprinids among cypriniforms, well few clupeoids. In is either already present an opening palatoquadrate cartilage earliest developmental stages we studied, or it forms later by resorption chondrocytes. Some may lack during all development. cobitids develops after bones have ossified mainly bone tissue quadrate metapterygoid. Previous reports are erroneous this area spatial separation metapterygoid from symplectic not formation fenestra cartilage. suggest referring type gap, QMG. Presence putative synapomorphy characiforms. Development Cobitidae. A QMG variously developed different degrees opsariichthyine danionine cyprinids. several clupeoids deserves further study.