Submitted to: Systematic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2008
Publication Date: 3/31/2009
Citation: Winkler, I.S., Scheffer, S.J., Mitter, C. 2009. Molecular phylogeny and taxonomy in leafmining flies (Diptera: Agromyzidae): Delimitation of Phytomyza fallén s. lat. and its species groups, with new insights on genitalic and host-use evolution. Systematic Entomology. 34:260-292. Interpretive Summary: Leafmining flies feed as larvae within plant tissues such as leaves, stems, and seeds, often causing extensive damage. There are thousands of species of leafmining flies, many of which are crop pests in the US and around the world. The evolutionary relationships among leafmining flies are largely unknown due to the lack of variable morphological features in this group. This research uses DNA sequence data from three independant genes to investigate evolutionary relationships and the history of host-use evolution in plant-feeding flies within the large genus Phytomyza and its relatives. We found that the taxonomy of this group needs to be updated as it does not currently reflect evolutionary history. This research will lead to changes in the classification of these insects and will allow us to better predict biological characteristics such as host-use. This research will be of interest to scientists, insect pest managers, and quarantine officials.
Technical Abstract: Phytomyza is the largest genus of leaf-mining flies (Agromyzidae), including over 530 species as previously delimited. Species of the very similar genus Chromatomyia are sometimes included in Phytomyza, and its status has been uncertain. Using 3,076 base pairs of DNA sequence from three genes (COI, CAD, PGD) and 113 exemplar species, we tested the monophyly of Phytomyza and Chromatomyia with respect to each other and to related genera. We also tested the monophyly of previously recognized species groups of Phytomyza and the relationships between these. Results indicate that Chromatomyia is polyphyletic and largely nested within Phytomyza; however, two small groups of species are more closely related to Ptochomyza and Napomyza. We therefore synonymize the genera Chromatomyia, Ptochomyza, and Napomyza with Phytomyza, recognizing Ptochomyza, Napomyza, and Phytomyza s.str. as subgenera of Phytomyza. We further recognize five major clades within Phytomyza s.str. which contain the majority of species previously placed in Chromatomyia and Phytomyza. Many previously recognized species groups were recovered as monophyletic or nearly so, but a few groups (e.g. robustella, atomaria grps.) required some emendation. We present a preliminary revision of species groups within Phytomyza s.str. based on our phylogeny and recent taxonomic literature, recognizing 24 species groups, but leaving many species unplaced. Evolution of internal pupation (within the host tissue), a defining character of the former Chromatomyia, is discussed with regard to the new phylogeny, and a correlation with stem- or leaf midrib-mining is suggested. The large size of the Phytomyza lineage and an inferred pattern of host-family specific species radiations make it a promising canidate for study of macroevolutionary patterns of host shift and diversification in phytophagous insects.