Taxonomic diversity of Passifloraceae sensu stricto along altitudinal gradient and on Serra dos Órgãos mountain slopes in southeastern Brazil

Abstract Altitudinal gradients, among other abiotic factors, are directly linked to species’ diversity patterns and distributions. Another important factor to be considered is the geographic position of a mountain chain, with oceanic and continental-facing slopes having distinct environmental conditions reflected in distinct phytophysiognomies. We examined the distributions of species of Passifloraceae sensu stricto along an altitudinal gradient (varying from 300 to 2,199 m.a.s.l.) in the Serra dos Órgãos National Park (PARNASO) in Rio de Janeiro state, southeastern Brazil. Field excursions were undertaken to record and collect specimens. Maps were prepared of the distribution of sampling efforts, taking into consideration altitudinal gradients and rainfall. The statistical analysis was made to define the patterns of richness and abundance within the altitudinal classes. Analyses of similarity, grouping and NMDS were made of the oceanic and continental slopes. A total of 19 species of Passifloraceae s.s. were encountered. The greatest species richness was found at intermediate elevations (1,100–1,300 m.a.s.l). The similarity index between the two exposure slopes was 28%, indicating distinct species compositions on different faces. Our data helps to define the distribution and species composition of Passifloraceae s.s. within the PARNASO, and should be useful for conservation actions there.