Revision of the South American freshwater pufferfishes genus Colomesus gill, 1885 (Tetraodontiformes: Tetraodontidae)

Abstract

Colomesus comprises small-sized, beautifully colored pufferfishes, which are endemic to Northern South America. The genus was revised half-century ago, and had its nomenclatural issues partailly solved. Currently, three valid species are known: the marine C. psittacus, and two freshwater, C. asellus e C. tocantinensis. In recent years, a wide sampling of the genus (809 specimens from 18 Institutions) has been studied by us, where we recognize that the C. asellus is, in fact, a complex of species. Until then, material from all subbasins of the Amazon, Orinoco and Essequibo River basins had been studied. However, most of this material is Brazilian, and a just a small number is from Peru, Venezuela, and Guyana. Morphological analyzes of 44 measures, osteological structures, and counts of vertebrae, pterygiophores, branquiostegais rays, and fin rays are being taken. Five freshwater species were diagnosed to date, the two valid and three others undescribed: C. cf. asellus, from the lower Essequibo River, Guyana; C. tocantinensis, from uplands drainages of the Guiana and Brazilian Shields; C. n. sp. 1, from the Río Orinoco basin, Venezuela; C. n. sp. 2, from the upper-middle Amazon River basin, of Brazil and Peru; and C. n. sp. 3, from the main Amazonian channels, Brazil. They differ from each other on the basis of several morphological attributes. However, material from Ecuador, Colombia, Trinidad and Tobago, Suriname, and Guiana Francesa, which lacks in Brazilian collections, remains to be studied. North American collections, otherwise, have many lots of Colomesus from those countries. Thus, this scholarship application is opportunity to accomplish more reliable results for this research and a more solid professional training to the student. (AU)