Review of wing morphology in fossil and modern species of humpbacked flies (Diptera: Phoridae).

Background: The wing veins of known fossil and living phorids are reduced, making them difficult to homologise. Consequently, different interpretations have led to much confusion over the years. However, veins are crucial for phylogenetic and taxonomy studies, especially for fossils. We addressed these challenges by studying Cretaceous specimens, which exhibit fewer reductions in wing veins compared to modern fauna, along with post-Cretaceous specimens that display recent wing patterns. Furthermore, we examined related families such as Ironomyiidae, Platypezidae, Opetiidae, and Lonchopteridae to show wing similarities to the Phoridae.

Results: We propose two wing models that include the majority of veins found in each taxon. The early model (Phoridae sensu lato, including Sciadocerinae + "†Prioriphorinae") consists of most Cretaceous species, except †Metopina goeleti from New Jersey amber, which displays a recent pattern. The recent model (Phoridae sensu stricto, i.e. Euphorida) is present in the majority of recent phorids. Based on this new interpretation, we re-evaluate three holotypes of Phoridae: †Euliphora grimaldii, †Prioriphora schroederhohenwarthi, and †Ulrichophora lobata. Additionally, we described a Phoridae specimen belonging to †Prioriphora in the Fouras-Bois Vert amber (France) and a new genus within the Ironomyiidae family in the San Just amber (Spain).

Conclusion: The newly proposed wing models facilitate rapid identification of Phoridae wing veins based on their degree of reduction. The two newly described specimens are the first records of these taxa in their respective localities.