Integrative Species Delimitation And Conservation Of Tarantulas (Araneae, Mygalomorphae, Theraphosidae) From A North American Biodiversity Hotspot

The Madrean Sky Islands of northern Mexico and the south-western United States are located in the Madrean pine-oak woodlands biodiversity hotspot'. This area is renowned for its exceptional flora and fauna, but comparatively little is known about arthropod diversity in this region. We obtained specimens of the tarantula genus Aphonopelma from five different mountain ranges (Huachucas, Pajaritos, Peloncillos, Santa Catalinas, and Santa Ritas) to assess patterns of diversity within the group. Species delimitation in tarantulas is difficult because they possess few informative morphological features. We implemented a rigorous methodological framework for delimiting species that incorporated multiple lines of evidence (molecules, distributional information, morphology, and breeding period) in an explicitly hypothesis-driven manner. Our integrative taxonomic approach delimited three species (all undescribed): one endemic to the Peloncillos, one endemic to the Santa Catalinas, and one that is more widely distributed in the Huachucas, Santa Ritas, and Pajaritos. These patterns of diversity and endemicity are comparable to other arachnids in the region and suggest that species-level diversity of stenotypic/dispersal-limited arthropods throughout the Madrean Sky Island Region may be underestimated. Ecological data are not widely available for Madrean Sky Island tarantulas and it is difficult to evaluate their conservation status. Several intrinsic (patterns of endemicity, limited vagility, and life history) and extrinsic (habitat degradation, commercial exploitation, and climate change) factors, however, suggest that these spiders may be of conservation concern. The approach taken in this study highlights the importance of considering multiple lines of evidence when species delimitation has direct implications on conservation.