CYTOGENETIC STUDIES ON FISHES OF THE FAMILY PIMELODIDAE (SILUROIDEI)

Four fish species of the family Pimelodidae were analyzed. Bergiaria w estermani and two different Pimelodus species have the same diploid ch romosome number (2n - 56). Despite some differences in chromosome stru cture, these species are highly similar in karyotype and differ from P imelodella sp., which presents a reduction in chromosome number to 2n = 46. The data confirm the extensive chromosome variability existing i n this family, characterized by intraindividual and/or population poly morphisms of a structural nature which may or may not be sexlinked, an d by the presence of supernumerary chromosomes.