NÚMERO CROMOSSÔMICO E PADRÕES DE HETEROCROMATINA DE DUAS ESPÉCIES DO GÊNERO ORNITHOCEPHALUS HOOK.(ORCHIDACEAE) DO NORDESTE DO BRASIL

Abstract

The Ornithocephalus genus belongs to the Orchidaceae family, and is restrict to America, being able to be found since Mexico to the south of Brazil. It still is a genre little studied karyologically. Considering it, the aim of this work was characterize the karyotype of two Ornithocephalus species found in Brazilian Northeast, by using banding techniques with the CMA and DAPI fluorochromes, in order to identify the chromosome number of these representatives of the genus, and their patters of heterochromatic bands. Both species analyzed presented 2n=56 chromosomes with complex chromocenter type interphase nuclei. They also presented the same patterns of CMA+/DAPI- pericentrometric heterochromatic bands, but they differ in the average sizes of their chromosomes, and the CMA+/DAPI- bands patterns found in the chromosomal terminals. The chromosome numbers and the types of interphase nuclei observed in the species of the Ornithocephalus genus corroborate the insertion of the genus in the subtribe Oncidiinae. The variation in heterochromatin composition of the species of the genus found in the Brazilian northeast allows us to consider it as a cytotaxonomic marker for these species, but it is an analysis that needs to be better investigated, which will allow a better understanding of the evolutionary mechanisms involved in species diversification of Ornithocephalus.