Abai, MR

6th International Congress of DipterologySignificance of gall polymorphism in the speciation ofgalling cecidomyiids (Diptera: Cecidomyiidae)Mishima, M. (1), S. Sato (2), & J. Yukawa (3)(1) The Kyushu University Museum, Hakozaki, Fukuoka 812-8581, Japan(2) Laboratory of Entomology, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan(3) Kyushu University, Hakozaki, Fukuoka 812-8581, JapanGenerally, gall shape is species-specific to gall midges (Diptera:Cecidomyiidae), but some species exhibit gall polymorphism. Masakimyiapustulae induces thin and thick type galls on the leaves of Euonymusjaponica and E. fortunei (Celastraceae). Leaf galls induced byPseudasphondylia neolitseae on Neolitsea sericea (Lauraceae) are apicallyrounded subconical on adaxial surface and hemispherical on abaxialsurface, and are divided into two types: the adaxial side protrudesprominently in one type and the abaxial side does so in another. Hartigiolafaggalli induces bivalve-shaped galls on adaxial- or abaxial surface ofFagus crenata (Fagaceae) leaves. In any case, individuals inhabitingdifferent types of gall cannot be distinguished morphologically from eachother. To discuss the significance of gall polymorphism in the speciation ofgalling cecidomyiids, we analyzed a region of the COI gene of mtDNA forthese gall midges to detect differences at the molecular level betweenindividuals inhabiting different types of gall. The sequencing dataindicated that the gall dimorphism was represented by the individuals withdifferent haplotypes in M. pustulae and H. faggalli. Differences betweenthe haplotypes were 2 bp (0.5 % of 439bp) in M. pustulae and 7 bp (1.6 %)in H. faggalli. There were 2 (1.4%) differences in the 146 deduced aminoacid residues in M. pustulae and 1 (0.7%) in H. faggalli. In P. neolitseae,different haplotypes did not represent individuals from different gall types.In all three cases, genetic distance between the haplotypes varies withspecies but it was not great enough to regard them as distinct species. Thus,gall differentiation starts at the molecular level prior to the morphologicaldifferentiation of gall midges and may lead to speciation because mortalityfactors would operate differently on the individuals inhabiting differenttypes of gall.164