First report of genus Peracecis (Diptera: Cecidomyiidae) in the Palearctic region, with description of a new species inducing leaf galls on Celtis sinensis (Cannabaceae)

The plant genus Celtis (Cannabaceae) hosts 26 species of gall midges (Diptera: Cecidomyiidae), consisting of 25 species of Celticecis in the Holarctic region and a single species of Peracecis in the United States. In this study, we newly record Peracecis from Japan, and Peracecis yukawai So, Elsayed and Tokuda, which induces pouch-shaped leaf galls on Celtis sinensis, is described as new to science. The new species is distinguishable from its congener by the combination of the following morphological features: tarsal claws with only a single basal tooth, sparse lateral setae in male, deeply divided hypoproct, slightly divided mediobasal lobes in male terminalia, and slightly divided larval terminal segment. Based on life history investigations, we found that P. yukawai leaves the plant earlier than closely related genera that utilize the same host plant. This is a possible strategy to avoid attacks from ectoparasitoids. Although Peracecis had previously been unplaced within any tribe of Lasiopteridi, our phylogenetic analysis strongly supports the inclusion of P. yukawai in Dasineurini. Based on the present results, Peracecis is now assigned to Dasineurini.