Gill-arch musculature of the quillback Carpiodes cyprinus (Cypriniformes: Catostomidae) with a comparison to cyprinids.

Although the gill-arch osteology of Cypriniformes has been well studied, comparable works on gill-arch musculature are scarce. The focus of previous studies has been on Cyprinidae while other families have received little or no attention. Consequently, generalizations for Cypriniformes have been made from the musculature of cyprinid gill-arches. This study describes the gill-arch musculature of a catostomid, the quillback Carpiodes cyprinus, and demonstrates that there are striking differences in the overall gill-arch musculature of catostomids in comparison to cyprinids, especially in the dorsal gill-arch region. Of the 23 muscles found in the dorsal gill-arch region of cyprinids, only 13 were present in C. cyprinus. Muscles that are absent include adductores 1-5, levator internus 4, levator ceratobranchialis 5 accessorius, retractor ceratobranchialis 5 externus, retractor ceratobranchialis 5 internus, and the retractor ceratobranchialis 5 transversus. In the ventral gill-arch region, the rectus communis is absent. The derived scrolling shape of the dorsal gill-arch skeleton associated with food processing is likely related to the change in musculature.