A Fine-Scale Hotspot at the Edge: Epigean Arthropods from the Atacama Coast (Paposo-Taltal, Antofagasta Region, Chile)

SIMPLE SUMMARY: The identification and surveying of fine-scale or micro-hotspots of biodiversity is a crucial strategy for better driving conservation efforts at global hotspots. This seems to be especially relevant at the edges of environments suitable for life, i.e., in desert margins with high levels of endemism, such as the Atacama coast. We surveyed a 100 km section of the Atacama coast including the emblematic Paposo and Taltal sites. We studied the taxonomic composition, richness, and abundance of terrestrial arthropods and were able to identify 173 arthropod species grouped into 118 genera and 57 families. The most abundant orders were Hymenoptera, Coleoptera, and Collembola, which accounted for 90.0% of the total captured. Most abundant families were Melyridae (Coleoptera), Poduridae (Collembola), Tenebrionidae (Coleoptera), and an indeterminate family of Psocoptera. Among remarkable Coleoptera, we were able to register Ectinogonia barrigai (Buprestidae) and Luispenaia paposo (Scarabaeidae). We also documented the presence of the tenebrionid Gyriosomus angustus, and several species of the genera Nycterinus (Paranycterinus) and Scotobius. We also could find the four species of scorpions that have been described for the Paposo area recently, and an undescribed species. The relevance of the area for future prospections and as a conservation site and a fine-scale hotspot of biodiversity has been confirmed based on the epigean arthropods. ABSTRACT: The Atacama Desert at its margins harbors a unique biodiversity that is still very poorly known, especially in coastal fog oases spanning from Perú towards the Atacama coast. An outstanding species-rich fog oasis is the latitudinal fringe Paposo-Taltal, that is considered an iconic site of the Lomas formation. This contribution is the first to reveal the knowledge on arthropods of this emblematic coastal section. We used pitfall traps to study the taxonomic composition, richness, and abundance of terrestrial arthropods in 17 sample sites along a 100 km section of the coast between 24.5 and 25.5 southern latitude, in a variety of characteristic habitats. From a total of 9154 individuals, we were able to identify 173 arthropod species grouped into 118 genera and 57 families. The most diverse group were insects, with 146 species grouped in 97 genera and 43 families, while arachnids were represented by 27 species grouped into 21 genera and 14 families. Current conservation challenges on a global scale are driving the creation and evaluation of potential conservation sites in regions with few protected areas, such as the margins of the Atacama Desert. Better taxonomic, distributional, and population knowledge is urgently needed to perform concrete conservation actions in a biodiversity hotspot at a desert edge.