Corydoras ornatus, a new species of callichthyid catfish from the Rio Tapajós Drainage, Brazil (Pisces, Siluriformes, Callichthyidae)

A new species of the neotropical callichthyid catfish genus Corydoras Lacépède, 1803, C. ornatus, is described and figured. It is compared with Corydoras pulcher Isbrücker & Nijssen, 1973, a closely related species

Aspidoras virgulatus n. sp., a plated catfish from Espírito Santo, Brazil (Pisces, Siluriformes, Callichthyidae)

Aspidoras virgulatus, a new species of Neotropical callichthyid catfish, is described and illustrated. It originates from tributaries of Rio Doce, State of Espírito Santo, Brazil

Two new species of the callichthyid catfish genus Corydoras from Brazil (Pisces, Siluriformes, Callichthyidae)

This paper contains descriptions and figures of two new species of the neotropical callichthyid catfish genus Corydoras Lacépède, 1803, from Brazil, Corydoras pulcher from Rio Purus, north of Lábrea, Est. Amazonas, and Corydoras steindachneri from Paranaguá, Est. Paraná. The relationships of the new species with other species of Corydoras are discussed

Karyotypic analysis of Baryancistrus

Three specimes of Baryancistrus aff. niveatus were studied cytogenetically by conventional staining, C banding, Ag-NORs, CMA3, DAPI and FISH with human telomeric probes. The results revealed a complement consisting of 52 metacentric, submetacentric and subtelocentric type chromosomes. C banding showed that heterochro-matin is located at pairs 1, 3, 6, 10, 11 and 22 in different positions. NORs were located at the short arm of pair 3, coinciding with a positive C-band. This region was also marked with CMA3, which also marked heterochromatic blocks in chromosomes 11 and 22. These regions were negatively stained by DAPI. These results revealed the presence of two different types of constitutive heterochromatin, probably due to their base composition. Chromosome bearing rDNA sites presented a difference in size in the NOR regions, probably due to heterochromatin and ribos-somal cistrons amplification. The localization of telomeric sequences by FISH revealed the conservative nature of this region. © 2004 Taylor & Francis Group, LLC