Catostomus


Catostomus is a genus of fish belonging to the family Catostomidae, commonly known as suckers. This genus of fish usually lives in freshwater basins. Most members of the genus are native to North America, but C. catostomus is also found in Russia. A majority of species inhabit western North America, with only C. catostomus, C. commersonii, and C. utawana being found in eastern North America.

Characteristics

The members of this genus have nearly cylindrical bodies. They have large, horizontal mouths, and their lips are very much papillose. They have complete lateral lines. They have from 54 to 124 scales, seven to 17 dorsal rays, usually seven anal rays, and 20 to 44 thin, unbranched rakers on their first gill arches. Their gas bladders have two chambers.
The young of many of the species in the genus have three dark grey blotches along their sides.

Hybridization

Catostomus from different species of the genus are known to readily hybridize with each other. The fish was used as a study object by biologists, revealing that fish hybridization can vary greatly from place to place. Although different species of this fish are reproductively isolated under normal circumstances this isolating barrier disappears to a certain extent as the environment changes. In addition, in areas where backcross and hybridization were widespread, the scientists found offspring of recombinant hybrids with new ecological characteristics that made them more adapted to the local environment and even more competitive with native species. Hybridization between different species of Catostomus fish occurs on a large scale, which means that many different environmental factors are involved in these geographic areas. This pattern of hybridization is also an effective mechanism for species self-protection. Although the hybrid forms of Catostomus fish break the common reproductive isolation between species, related research results can help to lead the protection of the waters where Catostomus fish live.

Species

Currently, 22 recognized species are in this genus:Catostomus ardens D. S. Jordan & C. H. Gilbert, 1881 Catostomus bernardini Girard, 1856 Catostomus cahita Siebert & W. L. Minckley, 1986 Catostomus catostomus
There are is also one candidate species:
The genus Pantosteus was formerly classified as a subgenus of Catostomus. However, more recent studies have found them to be a monophyletic group that forms a distinct clade from all other members of Catostomus, and they also have a different morphology and ecological preferences from Catostomus. Due to this, they are now treated as their own distinct genus.