Karyotype structure of Hypostomus cf. plecostomus (Linnaeus, 1758) from Tapajós River basin, Southern Amazon: occurrence of sex chromosomes (ZZ/ZW) and their evolutionary implications

Hypostomus is a group of fish with numerical and struc - tural karyotypic variability. Among them, only six species, three of which belong to the Amazon basin, show a sex chromosome. In this study, we present the karyotype structure of Hypostomus cf. plecos- tomus from the Teles Pires river basin in the municipality of Alta Flo- resta, MT. The species has 2n = 68 and the karyotype formula 14m+ 24sm+ 14st+ 16a (fundamental number (FN) = 120) in males and 15m+