Revision of the birch-associated genus (Diptera, Cecidomyiidae), with description of a new species from Japan and a taxonomic key to worldwide species.

(Betulaceae), or birch, is a Holarctic genus of trees and shrubs whose species have ornamental, industrial, and medical importance. Gall midges of the genus (Diptera: Cecidomyiidae: Cecidomyiidi) are exclusively associated with birches in the Palearctic region. In 2018, an undescribed species was discovered forming leaf galls on the midveins of on Mount Tara, Saga Prefecture, Kyushu, Japan.

A taxonomic revision and molecular phylogeny of the eastern Palearctic species of the genera Kieffer and Kovalev (Diptera, Cecidomyiidae, Asphondyliini), with descriptions of five new species of from Japan.

The genus (Diptera, Cecidomyiidae, Asphondyliini, Schizomyiina) was erected by Kovalev (1964) based on the presence of constrictions on the cylindrical male flagellomeres. In the present study, we examine the morphological features of and and found that the male flagellomeres are constricted also in , the type species of . Because no further characters clearly separating from were observed, we synonymize under .