DIOGO, Rui*; WAGEMANS, France; PARMENTIER, Eric; VANDEWALLE, Pierre; CHARDON, Michel: On the Homologies and Nomenclature of the Different Adductor Mandibulae Sections in Teleostean Fishes, with special regard to Catfishes

The adductor mandibulae complex has been a subject of discussion and uncertainties due to a wide range of differentations and fusions that have occurred during teleost evolution. The adductor mandibulae of numerous catfishes was studied in detail and compared with that of several other teleosts described in the literature. Our observations and comparisons demonstrate that: 1) The adductors mandibulae Aw, A2 and A3 of acanthopterygians correspond, respectively, to the Aw, A2 and A3 of ostariophysines; 2) The antero-dorso-lateral (A1) and the antero-ventro-lateral (A1-OST) sections of the adductor mandibulae, present, respectively, in acanthopterygians and in basal ostariophysines, are the result of two different patterns of differentiation of this muscle; 3) Some derived ostariophysines present a lateral section of the adductor mandibulae attached to the upper jaw (A0) that is not homologous with any other section of this muscle present in any other ostariophysine or acanthopterygian fish; 4) The configuration of the adductor mandibulae present in diplomystids seems to be the plesiomorphic condition for catfishes; and 5) The muscle retractor tentaculi, present in a large number of catfishes, is derived from the inner section of the adductor mandibulae (A3), and, thus, is not homologous with the lateral bundle of this muscle (A0) that inserts on the upper jaw in some derived ostariophysine fishes.