Morphological variation in the Weberian apparatus of Cypriniformes
Article first published online: 25 JUN 2007
Copyright © 2007 Wiley-Liss, Inc.
Journal of Morphology
Volume 268, Issue 9, pages 739–757, September 2007
How to Cite
Bird, N. C. and Hernandez, L. P. (2007), Morphological variation in the Weberian apparatus of Cypriniformes. J. Morphol., 268: 739–757. doi: 10.1002/jmor.10550
- Issue published online: 14 AUG 2007
- Article first published online: 25 JUN 2007
- NSF. Grant Number: IOB 0615827
- George Washington University
- Weberian apparatus;
- morphological variation
Cypriniformes (which includes the minnows, carps, loaches, algae-eaters, stone loaches, and suckers) is a morphologically diverse and incredibly speciose order of teleosts. It has been suggested that a number of evolutionary innovations, key to improved hearing and feeding, have played an important role in cypriniform fishes' success. One such innovation, the Weberian apparatus, is a novel assemblage of vertebral elements and modified ribs that relay and amplify sound pressure changes from the gas bladder to the inner ear. The Weberian apparatus unites Cypriniformes with other major orders into an extremely species-rich group of fishes, the Otophysi. Together, otophysan fishes comprise one of the largest groups of fishes in the world, as well as the majority of freshwater fishes. Here we present a detailed comparison of the Weberian apparatus in a number of cypriniform families using cleared and stained specimens. We present data regarding inter- and intrafamilial morphological variation within Cypriniformes. With few, but evolutionarily important, exceptions we find that diagnostic features of the Weberian apparatus characterize each family. Interspecific variation within each of the families Balitoridae, Gyrinocheilidae, and Catostomidae is only slight, whereas variation among subfamilies within Cyprinidae and Cobitidae is far more significant. This comparative study identifies a number of distinct morphologies, some of which appear highly correlated with ecological niche. For example, inhabiting swift-moving waters appears to be a key factor in the encapsulation of the anterior gas bladder in some cobitids, balitorids, and gobionin cyprinids. J. Morphol., 2007. © 2007 Wiley-Liss, Inc.