mygale_fig_sSentinel organisms provide helpful guidelines for conservation and management. They can be used to assess ecosystem or environmental integrity and to identify and prioritize biodiversity hotspot regions. The spider infraorder Mygalomorphae is exceptionally well-suited for monitoring conservation status of terrestrial ecosystems in the Meditteranean basin. They exhibit high habitat fidelity, limited potential for dispersal and restricted distributional ranges. Moreover, they are abundantly present in most Mediterranean habitats. Biologists, however, have long overlooked mygalomorph spiders due to their secretive habits and challenging taxonomy. The promising use of these spiders as bioindicators is therefore not fully developed. Here we propose to overcome these limitations by undertaking and ambitious multidisciplinary research utilizing mygalomorphs as a model system to study the processes underpinning Mediterranean biodiversity. Specifically, we will investigate population structure and demographic processes in the mygalomorph spider with the largest geographical and latitudinal range in Europe, Atypus affinis, and will characterize factors promoting speciation in the highly diverse Mediterranean Nemesiidae. GIS and novel molecular tools will be further use to investigate niche segregation at local scale in sympatric species of Nemesiidae. We will also identify endemism hotspots in the Iberian Peninsula and will use phylogenetic diversity to prioritize areas for conservation, as inferred from the phylogenetic interrelationships and potential distributions of Mediterranean Nemesiidae. Because of narrow ecological preferences and long life cycles, Mygalomorphs are particularly vulnerable to extinction. We will combine population genetic tools with ecological modelling techniques to identify demographic history of the protected spider Macrothele calpeiana, and the Canarian endemic Titanidiops canariensis, and will predict future effect of global warming on the distribution and viability of these species. We are fully committed to overcome traditional barriers to the diffusion of scientific research. In this regard, our alliance with a public natural history institution will facilitate transfer of knowledge to society through a variety of activities. We anticipate that results of our research will be relevant for conservation, management, and sustainable use of natural landscapes in the Mediterranean basin