Before it's too late: priority areas for conservation of cryptic and threatened species of troglobitic arthropods in the Brazilian semiarid

One of the most important steps in identifying priority areas for conservation is the assessment of species richness and their extinction risks. While most species remain undescribed, the identification of cryptic lineages is frequent in phylogenetic and phylogeographic studies. This is particularly common in troglobites, exclusively subterranean organisms. The Jandaira Formation, in the Brazilian semiarid, combines the occurrence of extensive karstic areas with hundreds of caves and subterranean aquifers in a region with intense paleoclimatic changes. This region is recognized for the richness of troglobitic species, some of which are widely distributed in heterogeneous areas. This suggests cryptic lineages that can be differentially exposed to anthropogenic threats, with distinct extinction risks regarding the nominal taxa of which they putatively belong. To test it, a large sampling was conducted and, by means of lineage delimitation analyses, the genetic structure of four troglobitic taxa, three aquatic and one terrestrial, was evaluated. In addition, the extinction risk of these lineages was assessed and priority areas for conservation were identified. The results indicated that while Cirolanidae sp. 1 (Isopoda) is a single species widely distributed, Cirolanidae sp. 2, Potiberaba porakuara (Amphipoda) and Kinnapotiguara troglobia (Hemiptera) present an extensive diversity of cryptic and endemic lineages, most of which are likely new threatened species. Furthermore, two priority areas for conservation of these lineages were identified. Thus, comparative phylogeography may represent a first step in the conservation of subterranean taxa, indicating areas that should be prioritized in a context of increasing threats and dwindling conservation resources.