Molecular Phylogeny of the Cristata Species Group of the Genus Colocasiomyia (Diptera: Drosophilidae)

Flies of the Colocasiomyia cristata species group depend their life cycles on specific host plants of the family Araceae and play important roles as species-specific pollinators in return. A pair of ‘stamenicolous’and ‘pistillicolous’species cohabit in the same inflorescence and such pairs have been reported from different host species and different geographical regions. To understand the evolution of host selection and cohabitation and the divergence between stamenicolous and pistillicolous species in the C. cristata group, we conducted molecular phylogenetic analyses. The mitochondrial ND2 sequences (maximum 858 base pairs) of 27 OTUs were analysed. Phylogenetic relationships reconstructed by the neighbour-joining, maximum parsimony and maximum likelihood methods were summarised in a consensus network. The resolution in the inferred phylogeny was higher than those in the previous cladistic studies based on the morphological characteristics. We recognised three main clades:the C. colocasiae-alocasiae, C. diconica-xenalocasiae and C. cristata-sulawesiana clades. Comparisons of ecological traits among species on their phylogenetic relationships revealed that the origins of cohabitation and stamenicolous and pistillicolous breeding habits are more complicated than thought in the previous hypothesis. Since the number of the species is limited in this study,more biogeographic information and comparative ecological studies based on reliable phylogenetic trees with comprehensive taxon sampling of both Colocasiomyia flies and their host plants will be necessary. Low Temperature Science, Vol. 69. Hal. 19-28