Marcada Diferenciação Cariotípica entre as “Manjubas” Atherinella blackburni e A. brasiliensis (Atheriniformes)

Abstract

Atheriniformes is represented by only three species in the Brazilian coast. Species and populations identifications in some small fishes, useful in biological conservation are restricted, due markedly to the absence of conspicuous morphological features. Generally small coastal fish are included at common sense in an indistinct polyphyletic group that depending on the geographic region may receive several popular designations. Among these often are included the Brazilians atheriniforms, whose cytogenetic data are still very limited. Aiming to identify the mechanisms of karyotypic diversification in this group, were analyzed cytogenetically Giemsa staining, Ag-NOR, C-banding and base-specific fluorochrome CMA3 therin Ath ella en blasis erinell a bl ac k burn i and /DAPI. Both species have A. bra silie n si s by 2n=48 chromosomes, but distinct karyotypes. So, A A. has 38m (metacentric) + 6sm (submetacentric) + 4a (acrocentric) (NF=92), while b ra sili c kburn i 4m +14 sm +18 st +12 a (NF=84). Ag-NORs sites (regions CG+ bla c k burn ) were present in the terminal portions of the short arms of pair 1 (m) in A. i and pair 3 (sm) in distributed in centromeric and pericentromeric regions, occupying much of the short arms in the most A. bra s iliensis . The high heterochromatin content in both species is two-armed chromosomes. Much of the heterochromatin of chromosomes of lac i is GC-rich. The striking structural chromosomal diversity between the species was apparently mediated by pericentric A. b kburn inversions and differential heterochromatinization process. Keywords: