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.
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