Integrative taxonomy reveals a new gall midge genus and species (Diptera: Cecidomyiidae) developing in the flower buds of Pongamia pinnata (Fabaceae) in Japan

The Ryukyu Archipelago of Japan is a biodiversity hotspot with a remarkable diversity of endemic plants and animals. Although recent biodiversity surveys have highlighted that gall midges (Diptera: Cecidomyiidae) are the most species-rich taxon of insects worldwide, only 43 species are known presently in the Ryukyus. In this study, an undescribed gall midge developing in the flower buds of Pongamia pinnata (Fabaceae) was found on Ishigaki Island, southern Ryukyus, Okinawa Prefecture, Japan. Morphologically, the gall midge belongs to the supertribe Cecidomyiidi (Cecidomyiidae: Cecidomyiinae), but it does not fit the definition of any of the tribes and genera classified of Cecidomyiidi. A molecular phylogenetic analysis including the main tribes of Cecidomyiidi was conducted and reinforced the results of morphological examination. Therefore, Ishigakidiplosis karamae Elsayed, gen. nov. et sp. nov. was introduced for what is no doubt a previously unnamed species. This new genus sheds light on the unique gall midges of the Ryukyus and highlights the importance of conducting further surveys to elucidate their diversity and evolutionary relationships to other known gall midges.