Abai, MR

6th International Congress of DipterologyPhylogeny, diversification, and host use evolution ofPhytomyza and Chromatomyia leaf mining flies (Diptera:Agromyzidae)Winkler, I.S. (1), S. Scheffer (2) & C. Mitter (1)(1) Department of Entomology, University of Maryland, College Park, MD 20742, USA(2) USDA Systematic Entomology Laboratory, BARC-W, Beltsville, MD 20705, USAThe importance of shifts to novel host plant groups for diversification inphytophagous insects has been the subject of much discussion, but littleformal analysis. The leaf-mining fly genera Phytomyza and Chromatomyia(Diptera: Agromyzidae) together form a monophyletic group well-suitedfor such analyses. These genera are comprised of about 640 describedspecies which can mostly be placed in species groups defined by similargenitalic morphology and the tendency to feed on a specific host plantfamily. A phylogeny estimate was obtained using over 3000 bases ofDNA sequence data from 100 species of Phytomyza and Chromatomyiaand from additional species in four related genera as outgroups. Resultsconfirm the monophyly of most recognized species groups, and underscorethe importance of host conservatism at the family level. Species feedingon Ranunculaceae, a primitive herbaceous plant family, show the mostgenetic and morphological diversity, suggesting a significant earlyradiation onto hosts in this family. However, later shifts to herbaceousasterid plant families have also resulted in significant radiations. Thegenus Chromatomyia is not monophyletic, with one major group feedingon Asteraceae and Poaceae, and another on herbaceous and woody hosts inseveral plant families; both are nested within Phytomyza. Morphology ofrepresentative species was also examined and compared to descriptions ofremaining species in the taxonomic literature to confirm monophyly ofspecies groups and to estimate the number of species belonging to each.Along with relative divergence times estimated from the molecular data,this allowed comparison of relative diversification rates across speciesgroups and higher lineages. Possible correlates of increased diversificationrate in this group are discussed.305