Taxonomia e biogeografia de Bromeliaceae na distribuição norte da Caatinga e Mata Atlântica do Brasil

Abstract

Bromeliaceae is a natural group widely distributed in the Neotropics and recognized mainly by the extremely reduced stem and alternate-spiraled leaves. Of the approximately 3,630 known species, 1,177 are exclusively Brazilian. Northeast Brazil has significant richness, potential for the discovery of novelties in Bromeliaceae and an alarming state of conservation, which makes it essential to carry out studies with the family in the region. Thus, this work aims to analyze biogeographical patterns of bromeliads in a portion of Northeast Brazil and to describe their taxonomic diversity, with emphasis on the states of Ceará (CE) and Rio Grande do Norte (RN), seeking to contribute to conservation measures. Using 2,671 georeferenced records compiled from online platforms, we analyzed richness, collection density, endemism, and how environmental variables influence the distribution of bromeliads in a freshwater ecoregion. For the taxonomic treatments, expeditions were carried out for collection, observation of ecological, phenological and geographical aspects, and five herbaria were visited to complement the morphological analysis. Our sample recorded 23 genera and 108 species in the studied area. Thirty-nine species were registered in CE, with two new occurrences and one of variety, besides 26 species for RN, of which four are new occurrences. Mean annual precipitation and altitude are important factors that affect the richness and distribution of the genera in the studied area, making the Atlantic Forest the domain with greater richness, collection density and endemism. On the other hand, a belt of low rainfall may be acting as a geographic barrier to moisturedependent genera and needs to be investigated further. We conclude that the two states in fact possess underestimated richness and that the richness and endemism of Bromeliaceae in the study area as a whole are linked to fragments of wet forest or high-altitude regions, which should be considered priority areas for the conservation of the group.