On the osteology and myology of catfish pectoral girdle, with a reflectionon catfish (Teleostei : Siluriformes) plesiomorphies

The configuration of the pectoral girdle bones and muscles of numerous catf ishes was studied in detail and compared with that of other siluriforms, as well as of other teleosts, described in the literature. The pectoral girdl e of catfishes is composed of only three bones, which probably correspond t o the posttemporo-supracleithrum (posttemporal + supracleithrum), scapuloco racoid (scapula + coracoid), and cleithrum of other teleosts. These latter two bones constitute the place of origin of the pectoral girdle muscles. Tw o of these muscles are related to the movements of the pectoral fin. These two muscles correspond, very likely, to the abductor superficialis and to t he adductor superficialis of other teleostean fishes. In relation to the pe ctoral spine (thickened first pectoral fin ray), it is usually moved by thr ee well-developed muscles, which are probably homologous with the arrector ventralis, arrector dorsalis, and abductor profundus of nonsiluriform teleo sts. The morphological diversity and the plesiomorphic configuration of the se muscles, as well as of the other catfish pectoral girdle structures, are discussed. J. Morphol. 249:100-125, 2001. (C) 2001 Wiley-Liss, Inc.