Floristic diversity, richness and distribution of Trentepohliales (Chlorophyta) in Neotropical ecosystems

Trentepohliales is one of the most diverse and abundant algal group of the terrestrial microflora in tropical regions; however, information about composition, richness and distribution of these algae in Neotropical regions are scarce. We described the flora and evaluated species richness and composition of Trentepohliales in four Brazilian different phytophysiognomies and analyzed the influence of environmental and spatial factors on species richness and distribution. Specimens of Trentepohliales were gathered from six natural areas in Brazil, and they were studied according to their vegetative and reproductive morphological traits. We applied tests to evaluate the richness and similarity in species composition in the different environments: rarefaction curves to compare richness; dendrogram with Jaccard's index to evaluate the similarity of species composition; Mantel's test to detect the influence of the spatial geographic distance on the assemblages; and partial linear regression to analyze the influence of the spatial and environmental factors on species richness. Thirty-three morphospecies were recorded; most of them in one location and none was observed occurring in all sampled areas. Rainforest areas showed the highest species richness and the species composition was variable among the areas. Partial linear regression revealed that the spatial features plus environmental features drove the Trentepohliales' species richness gradient. The composition of species of communities presented distance decay of similarity pattern, since differences in composition of such assemblages were positively related to the distance among the areas. In this way, the dispersion jointly with the variation of the environmental conditions may determine the Trentepohliales species composition in each ecosystem.