First chromosome data on Steindachneridion scripta (Pisces, Siluriformes, Pimelodidae) from Brazilian rivers: Giemsa, CBG, G-, and RE banding.

A cytogenetic study was performed on the large pimelodid species Steindachneridion scripta (Siluriformes, Sorubiminae) from the Paraná River basin (Brazil). Chromosome preparations were obtained avoiding sacrifice of the specimens, by means of lymphocyte culture, and several staining and chromosome banding techniques were applied. The karyotype consisted of 56 chromosomes, 24 metacentrics, 20 submetacentrics, 4 subtelocentrics, and 8 acrocentrics (fundamental number = 104). The first pair of acrocentric chromosomes (pair 25) consistently had a decondensed secondary constriction; the C-banding pattern of some chromosomes allows them to be considered cytogenetic markers (i.e., pairs 1, 3, 4, 6, 7, 9, 13, 23, and 24). G-banding and restriction enzymes provided patterns that helped improve chromosome pairing. This is the first report on a Neotropical pimelodid species of economic interest using several cytogenetic techniques and providing an integral karyotypic characterization.