SLAM Project - Long-Term Ecological Study of the Impacts of Climate Change in the natural forest of Azores: VII - Long-term arthropod monitoring in Graciosa Island

The data we present are part of the long-term project SLAM – Long Term Ecological Study of the Impacts of Climate Change in the natural forest of Azores, which was established in 2012 to monitor arthropod communities in Azorean forest habitats using standardised long-term ecological sampling. The main aim of this project is to understand how major biodiversity erosion drivers, including habitat degradation, biological invasions and climate-related pressures, affect the distribution, abundance and diversity of Azorean arthropods through time. Long-term monitoring is particularly relevant on oceanic islands, where biodiversity change may be expressed more strongly through species turnover, shifts in community composition and increases in introduced taxa than through immediate declines in total species richness. The SLAM framework also contributes to the early detection and documentation of new species occurrences, thereby improving baseline knowledge for conservation planning, biodiversity assessment and biosecurity. Sampling relies on passive flight-interception SLAM (Sea, Land and Air Malaise) traps, which are operated continuously and serviced at regular intervals to provide comparable seasonal and interannual samples. We sampled 17,064 specimens from samples from the years 2015-2021 out of which 16,491 were identified to the level of species (96.6%) or even subspecies (326 individuals) and 247 were identified to the order, family or genus level. The identified specimens belong to 17 unique orders, 82 families, 156 genera and 165 species and eight subspecies. Of these species and subspecies, 14 were endemic, 49 were native non-endemic, 86 were introduced and 24 have uncertain colonisation status. A total of 26 species were recorded for the first time on Graciosa Island, but none represents a new record for the Azores Archipelago. Amongst these newly-recorded species, two are Azorean endemics, five are native non-endemics, 16 are introduced and three have uncertain colonisation status, with most detected at very low abundance. New island records on Graciosa Island comprise nine spiders (Order Araneae), including two Azorean endemic spiders recorded for the first time on Graciosa, Neon acoreensis (jumping spider; Salticidae) and Savigniorrhipis acoreensis (dwarf sheet spider; Linyphiidae). The remaining newly-recorded spiders are: Agyneta decora (dwarf sheet spider; Linyphiidae), Enoplognatha mandibularis (cobweb spider; Theridiidae), Haplodrassus signifier (ground spider; Gnaphosidae), Neriene clathrata (sheetweb spider; Linyphiidae), Orchestina furcillata (goblin spider; Oonopidae), Theridion melanostictum (cobweb spider; Theridiidae) and Zelotes aeneus (ground spider; Gnaphosidae). New records also include eight beetles (Coleoptera): Amischa forcipata (rove beetle; Staphylinidae), Brassicogethes aeneus (pollen beetle; Nitidulidae), Carpelimus troglodytes troglodytes (rove beetle; Staphylinidae), Cathormiocerus curvipes (weevil; Curculionidae), Omosita discoidea (sap beetle; Nitudulidae), Phyllotreta procera (flea beetle; Chrysomelidae), Ptenidium pusillum (featherwing beetle; Ptiliidae) and Quedius curtipennis (rove beetle; Staphylinidae). Additional new records comprise one millipede (Diplopoda), Cylindroiulus latestriatus (julid millipede; Diplopoda, Julida) and three true bugs (Hemiptera): Buchananiella continua (minute pirate bug; Anthocoridae), Empicoris rubromaculatus (thread-legged bug; Reduviidae) and Pilophorus confusus (plant bug; Miridae). Further additions are one ant (Hymenoptera), Hypoponera eduardi (ant; Formicidae), one booklouse (Psocodea), Lepinotus reticulatus (booklouse; Trogiidae), two thrips (Thysanoptera), Anisopilothrips venustulus (thrips; Thripidae) and Ceratothrips ericae (thrips; Thripidae) and one bush-cricket (Orthoptera), Phaneroptera nana (katydid/bush-cricket; Tettigoniidae).