Meeting Abstract
Cypriniform fishes are characterized by several trophic novelties that have likely played an important role in the evolutionary success of this group. One such novelty, the palatal organ, is a dorsal mass of complexly arranged muscle fibers within the buccopharyngeal cavity tied to the branchial elements laterally and to the chewing pad caudally. In goldfish and carp this muscular pad is incredibly well innervated and produces localized protrusions that are used to trap edible items while bottom feeding. The palatal organ has only been investigated in those species with either a greatly hypertrophied vagal lobe (goldfish and carp) or species with a greatly hypertrophied palatal organ (Catostomidae and a few cyprinids). There is no comparative data on the histological structure of the palatal organ across the whole of Cypriniformes. The general assumption has been that the function of the palatal organ is conserved across cypriniforms, and requires the careful control made possible by a hypertrophied vagal lobe to function properly. Few have considered the possibility that the palatal organ may have become adapted for different functions during cypriniform evolution. However, before formulating testable functional hypotheses, the histological structure of the palatal organ in a diverse group of cypriniforms must first be analyzed. In this study, we investigate the muscular composition of palatal organs within 39 species, within several families. There was not a consistent difference in muscular architecture between members of Cobitoidea and Cyprinoidea. Nearly all species examined have some type of muscular palatal organ, characterized by a complex mesh of differently sized muscle fibers; one exception is Gyrinocheilus, which has very reduced muscularity of the palatal organ.
