Molecular phylogeny of the armored catfish family Callichthyidae (Ostariophysi, Siluriformes)

The family Callichthyidae comprises eight genera of fishes widely distributed across the Neotropical region. In the present study, sequences of the mitochondrial genes 12S rRNA, 16S rRNA, ND4, tRNA(His), and tRNA(Scr) were obtained from 28 callichthyid specimens. The sample included 12 species of Corydoras, three species of Aspidoras, two species of Brochis, Dianema, Lepthoplosternum, and Megalechis, and two local populations of Callichthys and Hoplosternum. Sequences of Nematogenys inermis (Nematogenyidae), Trichomycterus areolatus, and Henonemus punctatus (Trichomycteridae), Astroblepus sp. (Astroblepidae), and Neopleeostomus paranensis, Delturus parahybae, and Hemipsilichthys nimius (Loricariidae) were included as the outgroup. Phylogenetic analyses were performed by using the methods of maximum parsimony and maximum likelihood. The results of almost all analyses were very similar. The family Callichthyidae is monophyletic and comprises two natural groups: the subfamilies Corydoradinae (Aspidoras, Brochis, and Corydoras) and Callichthyinae (Callichthys, Dianema, Hoplosternum, Lepthoplosternum, and Megalechis), as previously demonstrated by morphological studies. The relationships observed within these subfamilies are in several ways different from those previously proposed on the basis of morphological data. Molecular results were compared with the morphologic and cytogenetic data available on the family. (C) 2003 Elsevier B.V. All rights reserved.

Biology of a catfish, Trichomycterus sp (Pisces, Siluriformes), in a pristine stream in the Morro do Diabo State Park, southeastern Brazil

The distribution, activity, diet, and reproduction of an undescribed catfish species of the genus Trichomycterus (Trichomycteridae) were studied in the Morro do Diabo State Park, an important conservation area in the Rio Paranapanema basin, State of São Paulo, southeastern Brazil. Trichomycterus sp. is a rheophilic species occurring solely in the riffle areas of the streams and hunts mostly immature aquatic insects during the day by picking them from the substrate. The population has a balanced sex ratio, but females were uncommon in the smallest and largest size classes suggesting that females demonstrate a more accelerated growth pattern. Presence of mature individuals throughout the year represents an opportunistic reproductive tactic for fishes living in fast flowing waters, where the clutches could be shifted by the current, but the high incidence of mature individuals in the wet season may be related to optimal environmental conditions for juveniles during that period. Because of the restriction of Trichomycterus sp. to riffle environments, the conservation of this species depends on the maintenance of the original characteristics of these headwaters. That demands protecting the riparian vegetation and consequently the stream from excessive siltation resulting from runoff and erosion.

Nuclear DNA content in 20 species of Siluriformes (Teleostei: Ostariophysi) from the Neotropical region

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Análise molecular e morfológica de exemplares de Trichomycterus valenciennes, 1832 da Chapada dos Guimarães (Bacia do Paraguai) e ensaio sobre o complexo de espécies Trichomycterus brasiliensis Lutken, 1874

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)