Systematics of the Lauxanioidea (Insecta: Diptera)

Smithsonian Institution, Washington DC

Investigators

Abstract

0075206 Gaimari Lauxanioidea (Diptera) are a large diverse lineage of flies (4 families, 209 genera and subgenera, ~2000 species), worldwide in distribution, that took two major evolutionary pathways in their larval feeding modes. On the one side, the pathway exemplified by the family Chamaemyiidae is one of larval predation on soft-bodied sternorrhyncan insects such as aphids, scales, and mealybugs. On the other, that represented by Lauxaniidae and Celyphidae is larval saprophagy, feeding in decaying plant material from forest leaf litter to bird nests. The remaining family Eurychoromyiidae is enigmatic, with only one described species whose larval feeding habits are unknown. Discovering the larval habits of this latter family and placing them within the context of one of these pathways are among the goals of this study. The current higher classification for the superfamily does not reflect phylogeny, so this project seeks to place the genera of Lauxanioidea into a phylogenetic context, constructing a natural, biologically predictive classification to reflect the interrelationships among lineages. The hypothesized phylogenetic relationships will be used to examine biogeographical histories of these flies, and to explore the significance of the major feeding shift between larval saprophagy and predation in the early stages of lauxanioid evolution. Within the predatory chamaemyiid lineage, feeding patterns and host shifts will be scrutinized with an eye towards understanding host specificity among species of different genera, providing an additional element of predictability to an important group of predators of Sternorrhyncha. Habitat and food requirements can also be highly specific for saprophagous taxa, and assessing these requirements in the context of a phylogenetic classification can aid in developing conservation strategies within areas with high litter content, such as forest ecosystems. Understanding lauxanioid relationships and associated patterns provides insight into the worldwide radiation of a highly diverse, functionally critical higher taxon. The relationship between lauxanioid diversification and patterns of historical biogeography will provide insight into the reasons for their present-day success, particularly in areas of highest diversity such as Southeast Asia and South America. The nuances of the feeding shift between saprophagy and predation are fundamental to many monophyletic groups of Diptera and other insects, and provide a step towards understanding the true ecological importance