Estudo citotaxonomico de especies do genero Lychnophora Mart. (Asteraceae: Vernonieae) em Minas Gerais

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

Genus Lychnophora Mart. has about 68 endemic species in campos rupestres in the states of Minas Gerais, Bahia and Goiás. Ecological conditions of this environment has possibly provided intense speciation, and these conditions could be one of the factors for this endemism. The biggest diversity is found in Minas Gerais, and this state is also considered the biggest centre of this genus disperseI. To contribute to the biosystematic study of the genus, a chromosomic study of 18 species of Lychnophora belonging to 3 sections was made; they were collected at Serra do Cipó, Carrancas and Diamantina regions, in the state of Minas Gerais. For meiotic analysis, floral buds were fixed in Carnoy s solution, stocked in 70% ethanol and cytologic preparation were obtained through anthers squashing in 1.2% carmine solution. For mitotic analysis cypselas root tips were used, treated in 8-hydroxyquinoline and fixed in Camoy s solution. The slides were prepared through Giemsa technique. Three chomosome numbers, n=17, 18 and 19, were found but they were not always coincident with previous reports. In L. staavioides a polyploid population (n=34) was detected. Normality range of tetrads and pollen grains feasibility were also analysed. These ranges were normal in most analysed species with the exception of L. rupestris that presented a low normality range of tetrads. These different chromosomic numbers are distributed through the 3 sections species; in other words, they are not distinctive characters in infragenic leveI. On the other hand, they are very important to differentiate some species whose limits are questioned by taxonomists. Results confirm, most of ali, the taxonomic proposition presented by Semir, in 1991

ASSUNTO(S)

compostas cromossomos

ACESSO AO ARTIGO

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