Biogeography and comparative cytogenetics between two populations of Hoplias malabaricus (Bloch, 1794) (Ostariophysi: Erythrinidae) from coastal basins in the State of Bahia, Brazil

The species Hoplias malabaricus is a predator fish found in nearly all cis-Andean basins. From a cytogenetic point of view, this species comprises, at least, seven differentiated karyomorphs. Several localities have been formerly analyzed in Brazil, however, some regions, such as Bahia State, remain underrepresented. Recently, the Brazilian Environment Ministry classified both Itapicuru and Contas river basins (entirely located within Bahia territory) as priority conservation areas, whose biodiversity status lacks enough information. Therefore, the goal of the present work was to characterize, cytogenetically, populations of H. malabaricus from both basins, by using conventional staining, Ag-NOR and C-banding techniques. All specimens presented a diploid number of 2n = 40 with metacentric/submetacentric chromosomes, without differences between sexes, thereby representing the so-called "karyomorph F". The first metacentric pair presented a remarkably larger size in relation to the other pairs. The NORs were multiple, comprising the terminal region on long arms of two chromosomal pairs in both populations. However, the C-banding pattern was somewhat distinguishable between samples. Although sharing heterochromatic blocks at centromeric region of all chromosomes, the population from Itapicuru River basin appeared to have some more conspicuous blocks than those observed in the population from Contas River basin. The similar karyotype observed in both populations suggests a common geological history between them. The present results represent an advance in the knowledge about the cytogenetic pattern of H. malabaricus populations from poorly studied basins. A espécie Hoplias malabaricus é um predador que ocorre em praticamente todas as bacias cis-andinas. Sob o ponto de vista citogenético, ela compreende, pelo menos, sete cariomorfos diferenciáveis. Várias localidades já foram previamente analisadas no Brasil, porém, algumas regiões, como o Estado da Bahia, permanecem pouco amostradas. Recentemente, o Ministério de Meio Ambiente classificou as bacias do rio Itapicuru e Contas (inteiramente localizadas na Bahia), como áreas prioritárias de conservação, cuja biodiversidade carece de informações suficientes. Neste sentido, o objetivo do presente trabalho foi caracterizar citogeneticamente populações de H. malabaricus nessas bacias, por meio de técnicas de coloração convencional, Ag-RON e bandamento C. Todos os espécimes e populações analisadas apresentaram número d