Pseudoscorpiones (Arachnida) of the Brazilian oceanic islands

Abstract

Pseudoscorpiones are compose an ancient order of arachnids, occur in a wide variety of terrestrial habitats worldwide, with representatives of various genera occurring exclusively in insular habitats. The primary objective of this study was to determine the composition and distribution of Pseudoscorpiones within the Brazilian equatorial oceanic islands. To determine Pseudoscorpiones communities and distribution in coastal environmental habitats of the Brazilian equatorial oceanic islands (Fernando de Noronha archipelago, Rocas Atoll and St. Peter and St. Paul rocks), was defined three zones along the insular environmental gradient in the Brazilian equatorial oceanic islands. These zones include the Sand Beach (SB) closest to the intertidal zone, the Slope Forest (SF) with a sloping terrain and the Top Forest (TF) farthest from the beach. Collecting points were distributed in each zones (SB, SF, and TF) at distances greater than 1 km, with four samples collected at each point approximately 12.5 m apart from each other. The TF zone is observed only in Fernando de Noronha. In our study we found pseudoscorpions exclusively on the islands of the Fernando de Noronha archipelago. We collected 5 species from the Hesperolpiidae and Syarinidae families. The SF habitats exhibited greater species richness, while the Upper Forest habitats showed greater population abundance. Notably, we recorded pseudoscorpions (Ideoblothrus amazonicus) in bird nests (Sula dactylatra) on Rata Island, suggesting the use of nests as habitat, reproduction, and, possibly, occasional transport to and from other habitats. No pseudoscorpions were found in SB environments. Landscape changes and tourism can threaten this incredible newly discovered community, vital for monitoring environmental changes in this delicate ecosystem.