Taxonomy of Finfish

2.1.5.11 Pectoral girdle

These are paired bony structures on either side of the fish in the head region inserted laterally in most cases. They bear the pectoral fin and pectoral spine in catfishes. These articulate and are attached to the 'post-temporal bone of the cranium. Besides the spine an elongated cleithral process (Fig. 22 A) is visible above the pectoral fin at the side in catfishes. This may be rugose and prominent in some genera. The pectoral spines are mostly stout, strong, serrated along the outer edge or smooth, but in most Cases they are strong, with anteriorly directed (antrorse) serrations; in some both the inner and outer edges are serrated, where the direction of the serrations are towards the posterior end it is called retrorse. (Fig. 22 A) In Erethistes pussilus the spine serrations are different; they are divergent (Fig. 22 B). Some fishes exhibit a long filament from the tip of the pectoral spine.

Fig. 22. Pectoral girdle of Rita rita. A. Showing (PSP) pectoral spine with antrose teeth on inner edge and retrorse teeth on outer edge. CL = Cleithrum. CLAM. = Upward directed short narrow arm of Cleithum. CP = Cleithral process. O = Coracoid bone. TNL = Tunnel. B. Divergent serrations along outer edge in Erethistes pussilus.