Taxonomy of Dissomphalus Ashmead (Hymenoptera, Bethylidae) from Fiji and Solomon Islands, with Description of Twenty-Seven New Species

This study presents a comprehensive taxonomic revision of the genus Dissomphalus Ashmead (Hymenoptera, Bethylidae) in the southwestern Pacific, focusing on specimens from Fiji and the Solomon Islands. Dissomphalus is the most species-rich genus within Bethylidae, with a global distribution, yet it remains poorly documented in the Oceanian region. We examined 151 male specimens collected in these islands. As a result, we describe 27 new species, 25 from Fiji and 2 from the Solomon Islands. Diagnostic morphological features, detailed illustrations, and an identification key for all species are provided. These findings substantially expand the known diversity of Dissomphalus in Oceania. Our results underscore the importance of taxonomic research in underexplored regions and highlight the potential for high levels of species endemism in island ecosystems. This revision contributes to a better understanding of the genus’ biogeographical distribution and provides essential tools for future biodiversity assessments and conservation efforts in the southwestern Pacific.