Relationship with fungi is one of the habitat adaptation of Sciaridae. While the earlier studies suggested that many fungus gnats are playing as the important vectors of various fungus diseases on plants and mushrooms, evidences have not been well reported. Based on a multi-gene phylogeny, by the Bayesian framework, we propose the correlation of four morphological characters of adults and habitat adaptation from saproxylic to phytophagous in the Sciaridae. Our results suggest that the evolution of habitat transition from dead plant litter to the live plant is related to habitat adaptation to the phytophagy and the morphological characters of fore tibia apex is also related to the functional linkage between these traits. We performed Bayes factor-based tests, referred with evolutionary pathway test (EPT), to decide the correlated traits gained the during evolutionary processes. The EPTs strongly suggest that fore tibia structures appeared first and followed by plant-feeding adaptation. The divergence time estimations of Sciaridae are also largely congruent with the fossil records. The members of subfamily Megalosphyinae have radiated explosively and contemporaneously since the Oligocene, with the expansion of modern grasslands and the increase of herbivores. Consequently, we suggest that the evolutionary benefit of tibial structure may be closely related with the fungal carrying in Sciaridae.

• Seunggwan Shin(Insect Biosystematics Laboratory, Seoul National University)
• Hyojoong Kim(Department of Biology, Kunsan National University)
• Sunghoon Jung(Department of Entomology, University of California, Riverside)
• Seunghwan Lee(Insect Biosystematics Laboratory, Seoul National University)