ABSTRACT
Background: With the increasing recognition of the significance of arachnid conservation, it is crucial to allocate greater efforts towards implementing targeted monitoring programmes. Despite recent studies, our understanding of arachnid populations in Portugal remains limited. This study serves as the initial inventory of arachnids (Araneae and Opiliones) within the Castro Verde Special Protection Area (SPA) located in Beja, southern Portugal. The surveys were conducted during the spring of 2012 across 80 open grasslands that were grazed by cattle and sheep. New information: A total of 71 species of Araneae and two species of Opiliones have been identified. Notably, three spider species, namely Argennasubnigra, Civizelotesibericus and Walckenaeriacucullata, are documented for the first time in Portugal. Additionally, two harvestmen species (Dasylobusibericus and Homalenotusbuchneri) and 14 spider species (Cheiracanthiumpennatum, Haplodrassusrhodanicus, Marinarozelotesminutus, Tapinocybaalgirica, Agraecinalineata, Tibellusmacellus, Talaverapetrensis, Tetragnathaintermedia, Dipoenaumbratilis, Enoplognathadiversa, Neottiurauncinata, Ruborridionmusivum, Theridionpinastri and Xysticusgrallator) are recorded for the first time in the Beja District. The occurrence of each documented species within the SPA, including family and species details, is presented, underscoring the significance of the Castro Verde SPA for arachnid conservation. These findings contribute novel insights into the biodiversity of the Castro Verde SPA, emphasising the necessity of incorporating this area into arachnid diversity conservation efforts.