Estudo das relações filogenéticas de trichomycteridae (teleostei, siluriformes) com base em evidências cromossômicas e moleculares.

Abstract

Trichomycteridae is a family of small-sized catfishes which are widely distributed throughout Central and South America. This family has 218 described species, distributed in 44 genera and about 100 species belong to the genus Trichomycterus. Trichomycteridae is currently divided into eight subfamilies: Copionodontinae, Trichogeninae, Trichomycterinae, Sarcoglanidinae, Glanapteryginae, Tridentinae, Stegophilinae and Vandelliinae. All of these subfamilies are demonstrably monophyletic, except Trichomycterinae. Only a few studies have been conduced so far trying to solve the relationships among Trichomycteridae as well in other fields like Cytogenetics. The diploid chromosome number ranges from 2n=50 in Trichomycterus sp. to expected 2n=64 in Vandellia cirrhosa, although most species of this family have 2n=54 chromosomes. Species of Copionodon (present study) and Trichogennes, considered the most primitive genera in Trichomycteridae, have 2n=54, suggesting that this may be the ancestral diploid number of the family and that few chromosome changes occurred in Vandellia and in some Trichomycterus. Molecular data obtained in the present study show that Ituglanis is a monophyletic group and sister-group of all Trichomycterus, except T. hasemani that seems related to the subfamily Vandelliinae (that is monophyletic in all analysis). In the phylogenys based on molecular data Sarcogoanidinae and Glanapteryginae are not related as suggested in the hypotheses based on morphological data. If T. hasemani and Scleronema angustirostris, are excluded, not only Trichomycterinae, but also, Trichomycterus appear as monophyletic groups which differ from currently hypothesis based on morphologic data.