Genetic and morphological variation in the Bulbophyllum exaltatum (Orchidaceae) complex occurring in the Brazilian “campos rupestres”: implications for taxonomy and biogeography

The Bulbophyllum exaltatum complex comprises 15 described taxa, and present a number of unresolved taxonomic questions, especially among populations found in the Brazilian campo rupestre vegetation. Allozymes were examined in 33 populations to determine the degree of genetic variability between them and their degree of differentiation to better define the taxa of this group. Additionally morphometric analyses were also performed on representatives of 24 populations. All of the populations examined demonstrated high levels of variability and none of the species formed distinct groups comprising all of the conspecific populations. However, the populations primarily grouped according to their regional occurrence, with a distinction between populations of the states of Minas Gerais and Bahia, which coincided with the geophysical disjunction of the mountain chains where they occur. It is probable that hybridization or incipient differentiation is contributing to the elevated genetic identity observed among the populations, generating a reticulated grouping pattern.