Pre-zygotic barriers were not found between the two varieties, and these remain isolated due to post-zygotic events. The two varieties demonstrate marked differences in their morphology, floral biology, phenology and genetic make-up, all of which indicate that they should be treated as two distinct species. A complete revision involving the other varieties of the C. desvauxii complex will be necessary in order to define these two taxa formally.

The Melocactus spp. displayed levels of genetic variability lower than the values reported for other cactus species. The evidence indicates the occurrence of introgression in both species at two sites. The high F(ST) values cannot be explained by geographical substructuring, but are consistent with hybridization. Conversely, morphological differentiation in M. paucispinus, but not in M. concinnus, is probably due to isolation by distance.

-(Reproductive biology of Melocactus glaucescens Buining & Brederoo and M. paucispinus G. Heimen & R. Paul (Cactaceae), in the Chapada Diamantina, northeastern Brazil). The reproductive biology of Melocactus glaucescens and M. paucispinus (Cactaceae) was studied in the municipality of Morro do Chapéu, Chapada Diamantina, Bahia State, comprising the phenology, floral biology, pollination and mating system of the species. It was recorded flowering and fruiting periods, flower visitors, frequency and kind of visits, and the strategy and behavior of the visitors on the flowers. Experimental pollinations were carried out to determine the mating systems of the species. The flowering period of both Melocactus species overlapped during the study period. The floral characteristics of the species are typical of ornithophily: showy colors, tubular structure, and nectar with low concentration of solutes, between 20% and 30%. The hummingbird Chlorostilbon aureoventris Boucier & Mulsant (1948) was the most frequent flower visitor, performing 82% and 89% of the visits in M. paucispinus and M. glaucescens, respectively. Other hummingbird and butterfly species also visited the flowers of both species. The overlap in the flowering period and the similarity in the guild of pollinators of those and other sympatric species of Melocactus favour the occurrence of hybridization, as it has been observed in that area. Melocactus glaucescens presented self-incompatibility and allogamy. Conversely, M. paucispinus is self-compatible and autogamous, however presenting lower fruit set in selfing than in outcrossing, possibly due to the occurrence of inbreeding depression.

Cattleya elongata is a rupicolous orchid species spread throughout and endemic to outcrop islands in campo rupestre vegetation of the Chapada Diamantina, northeastern Brazil. We scored nine natural populations of C. elongata for morphological and genetic variability, covering the whole distribution area of the species, using allozymes and ISSR markers and morphometric multivariate analyses. Genetic variability in allozimes was relatively high (H e = 0.12-0.25), and unexpectedly higher than the values based on ISSR (H e = 0.16-0.19). The populations present moderate structuring (allozymes, U PT = 0.14; ISSR, U PT = 0.18) and low inbreeding (allozymes, F IS = 0.06). Genetic similarity among the populations was high in both markers, in spite of the discontinuity of the outcrops of the Chapada Diamantina. We found no particular biogeographical pattern to the distribution of the genetic and morphologic similarity among the populations of C. elongata. We found high morphological variability with moderate differentiation among the populations. We did not find any correlation among genetic, morphological, and geographical distances, and among the variability found in the morphological and genetic markers. The differences observed between the two genetic markers and the various morphological markers examined here indicated that the isolated use of any single parameter of these different populations for conservation planning or management would not consider all of the variability to be found in the species, as found in other Brazilian campos rupestres plants.