Madagascar is one of the world’s greatest biodiversity hotspots, yet taxonomic knowledge is generally depauperate for smaller taxa such as arthropods. Theridiidae is one of the most speciose families of spiders worldwide, and a good example of a poorly known megadiverse group that is expected to contain hundreds of Malagasy endemics. The kleptoparasitic members of the subfamily Agyrodinae are a case in point, with only 6 species recorded in Madagascar, and no new species described in the previous 140 yrs. Fieldwork in the Analamazaotra rainforest reserve complex in eastern central Alaotra-Mangoro region focused on the ecology and behavior of argyrodine kleptoparsites in webs of several host species. Here, we describe the new species from that work and provide taxonomic and systematic groundwork for placing known argyrodine species by adding 2 new genera. Lokitandroka gen. nov. is a Malagasy and Mascarene endemic containing 5 species, 4 of which are described here: Lokitandroka rabesahala Pett and Agnarsson sp. nov., Lokitandroka ratsimanga Pett and Agnarsson sp. nov., Lokitandroka rinha Pett and Agnarsson sp. nov., Lokitandroka tiana Pett and Agnarsson sp. nov., furthermore, Lokitandroka minax comb. nov., is redescribed based on type material. Famakytta gen. nov. accommodates Famakytta analamazaotra Pett and Agnarsson sp. nov., and several Old World species transferred here. Furthermore, we describe the first Malagasy species of 3 genera: Argyrodella ampingamena Pett and Agnarsson sp. nov. (second globally), Deelemanella helmscahani Agnarsson and Pett sp. nov. (third globally), and Neospintharus matjazkuntneri Agnarsson and Pett sp. nov. We review several Seychelloise argyrodines for which high-quality illustrations are available and transfer several species, providing the additional new combinations: Famakytta fissifrontella comb. nov., Famakytta flavescens comb. nov., Famakytta miniaceus comb. nov. We provide a phylogenetic context for the new genera and species and discuss their relevance for the global argyrodine biota.
Brogan L Pett, Elodie Ferreira, Ingi Agnarsson, Megadiverse Madagascar: new species and genera of argyrodine spiders (Araneae, Theridiidae, Argyrodinae) from the eastern rainforest reserve Analamazaotra, Insect Systematics and Diversity, Volume 9, Issue 6, November 2025, ixaf047, https://doi.org/10.1093/isd/ixaf047