Morphological re-examination reveals that Campylomyza serrata Jaschhof, 1998 is a complex of five cryptic species (Diptera: Cecidomyiidae, Micromyinae)

The micromyine gall midge Campylomyza serrata was described by the author in 1998 on the basis of three male specimens from a single locality in Northern Germany. Since then, a number of additional specimens from several European countries were assigned to this species and published as C. serrata. Now, almost 20 years later, all these specimens plus a few others from previously undetermined Campylomyza material in the author’s collection, altogether 56 males, were gathered for a morphological re-examination. As a result, Campylomyza serrata sensu Jaschhof (1998) is revealed to be a complex of five cryptic species, including Campylomyza angulata spec. nov., Campylomyza appendiculata spec. nov., Campylomyza lapponica spec. nov., and Campylomyza zwii spec. nov. In the present paper, Campylomyza serrata and the new species related to it are defined using characters of the male genitalia. A key is provided that facilitates the identification of males of these species and of Campylomyza spinata, the sixth known member of the serrata group. Finally, various issues related to the identification of serrata-like species (and other taxonomically difficult Micromyinae) are discussed.