Floristic and biogeographical synthesis for the caatinga phytogeographical domain

Overlooked during most of the twentieth century, the Caatinga Phytogeographical Domain (DFC) has been recognized in the last decades as a unique natural area with much more diversity and endemisms than previously assumed. We are experiencing in the last decades an increase in the publication of floristic and phytosociological studies for the DFC, what offers the opportunity to produce a synthesis for this region. We aimed at evaluating how many species have been collected, their frequency, how many species are expected to exists, and which environment types are more or less sampled. We also mapped which are the most overlooked geographical regions within the CPD. We thus seek to summarize the floristic and phytosociological surveys produced for Caatinga and to sumarize the plant diversity and biogeographical patterns for this region. We evaluate the issue of floristic similarity between different environment types within Caatinga using multivariate analysis and compared the floristic similarity among different subtypes of Caatinga. We also show that areas in crystalline and sedimentary terrains differ not only floristically but also structurally, with different lifeform spectra in each environment. We offer here a general overview of the plant divertity in the DFC, making a synthesis of the available surveys, a synthesis of the recorded species and finally a biogeographical synthesis. Thus, we sumarize here a considerable amount of floristic and phytosociological data scattered in the literature and offer a general overview for the Caatinga domain (AU)