Contributions to the knowledge of the ants (Hymenoptera: Formicidae) of southern Portugal: faunistic and taxonomic notes

Abstract Background The ant fauna of southern Portugal remains insufficiently documented, with relevant gaps in both distributional knowledge and taxonomic resolution. Historical sampling has been geographically uneven, and several species complexes require modern reassessment. This study aimed to provide an updated overview of ant assemblages in southern Portugal, focusing on poorly surveyed areas and evaluating distributional novelties and taxonomic uncertainties. Results In May 2025, an extensive field survey was conducted across the districts of Algarve, southern Setúbal, and Baixo Alentejo, primarily targeting undisturbed and rural habitats. A total of 58 species belonging to three subfamilies were recorded, with Myrmicinae representing the most diverse group. The assemblage reflects a typically Mediterranean composition, dominated by thermophilous ground-nesting species and complemented by a diverse arboreal component within Formicinae. Three species are newly recorded for Portugal: Tapinoma magnum , Plagiolepis pyrenaica , and Messor erwini . Several additional taxa represent significant southern Portuguese range extensions, including Camponotus ruber , Camponotus gestroi , Myrmica aloba , and Temnothorax alfacarensis . Multiple cryptic taxa were detected, including two potentially undescribed species ( Formica sp. 1 and Temnothorax sp. 1), highlighting unresolved taxonomic complexity. Conclusions The results substantially refine current knowledge of southern Portuguese ant diversity and confirm that the regional fauna remains incompletely characterized. The detection of cryptic and potentially undescribed taxa emphasizes the importance of integrative taxonomic approaches combining detailed morphological analyses and molecular data. Continued targeted surveys and critical reassessment of historical records are essential to achieve a more complete and stable understanding of Portugal’s myrmecofauna.