Morphometric studies of males and females of species of oligotrophine Cecidomyiidae reared from flower heads of seven genera of Asteraceae (Centaurea, Cirsium, Hieracium, Hypochoeris, Inula, Reichardia, and Saussurea) demonstrated, despite great overall morphological conformity, many instances of statistically significant differences between the species. Measurement values of structures in adult specimens were corrected for allometric deviations according to a procedure representing a further development of a method previously used for taxonomic purposes in gall midges. No galls produced by these midges have been observed. Beyond adults, also pupae and larvae were studied. Two Dasineura species and several Jaapiella species are represented. Four new species are described: Dasineura vulgatiformiae Sylvén, Jaapiella hypochoeridis Sylvén, Jaapiella pilosellae Sylvén, and Jaapiella reichardiae Sylvén.