Phylogeny, taxonomy and flower-breeding ecology of the Colocasiomyia cristata species group (Diptera: Drosophilidae), with descriptions of ten new species

Abstract

The phylogeny of the Colocasiomyia cristata species group is reconstructed as a hypothesis, based on DNA sequences of two mitochondrial and six nuclear genes and 51 morphological characters. The resulting tree splits this species group into two clades, one of which corresponds to the colocasiae subgroup. Therefore, a new species subgroup named as the cristata subgroup is established for the other clade. Within the cristata subgroup, three subclades are recognized and each of them is defined as a species complex: the cristata complex composed of five species (including three new ones: C. kinabaluana sp. nov., C. kotana sp. nov. and C. matthewsi sp. nov.), the sabahana complex of two species (C. sabahana sp. nov. and C. sarawakana sp. nov.), and the xenalocasiae complex of five species (including C. sumatrana sp. nov. and C. leucocasiae sp. nov.). There are, however, three new species (C. ecornuta sp. nov., C. grandis sp. nov. and C. vieti sp. nov.) not assigned to any species complex. In addition, breeding habits are described for four cristata-subgroup species, each of which monopolizes its specific host plant. And, data of host-plant use are compiled for all species of the cristata group from records at various localities in the Oriental and Papuan regions. The evolution of host-plant selection and sharing modes is considered by mapping host-plant genera of each species on the phylogenetic tree resulting from the present study.

Coexistence mechanisms of Colocasiomyia species (Diptera: Drosophilidae) sharing inflorescences of Alocasia odora (Araceae) as a host plant: Comparison between two‐ and three‐species systems

“…(2013) and Takano et al . (2021) reported breeding habits in some one‐to‐one systems where a single Colocasiomyia species monopolizes a single host‐plant species. In contrast, Toda and Lakim (2011) reported that 12 species of the baechlii group coexisted in Sabah, partially separating from each other in local distribution, phenology and selection of host‐plant species.…”

“…The pollination mutualism between Colocasiomyia flies and aroid plants vary in numbers of fly and plant species involved, from one-to-one to multiple-to-multiple systems (Sultana et al 2006;Takano et al 2021). Takenaka et al (2006), Fartyal et al (2013) and Takano et al (2021) reported breeding habits in some one-toone systems where a single Colocasiomyia species monopolizes a single host-plant species.…”

“…The pollination mutualism between Colocasiomyia flies and aroid plants vary in numbers of fly and plant species involved, from one-to-one to multiple-to-multiple systems (Sultana et al 2006;Takano et al 2021). Takenaka et al (2006), Fartyal et al (2013) and Takano et al (2021) reported breeding habits in some one-toone systems where a single Colocasiomyia species monopolizes a single host-plant species. In contrast, Toda and Lakim (2011) reported that 12 species of the baechlii group coexisted in Sabah, partially separating from each other in local distribution, phenology and selection of host-plant species.…”

“…1) (Carson & Okada, 1980;Okada, 1980;Honda-Yafuso, 1983;Toda & Okada, 1983;Yafuso, 1994). Compiling all records of host-plant use by species of the cristata group, Takano et al (2021) addressed the evolution of host-plant selection and sharing modes in this species group. Based on phylogenetic analyses, they classified the cristata group into the cristata and colocasiae subgroups, and the former subgroup into the cristata, sabahana and xenalocasiae complexes.…”

“…Okada (1980) hypothesized that this cohabitation on the same host plant was established by a pair of ancestors of the colocasiae subgroup and of the xenalocasiae complex, and that such a pair dispersed and differentiated into the three extant pairs in different geographic areas. This hypothesis was strengthened by the ancestral-state reconstruction for host plants in Takano et al (2021). The cohabitation would have been achieved by microallopatric breeding-site differentiation along the spadix of host plants between two species of the ancestral pair: the ancestor of the colocasiae subgroup would have changed its breeding habits from pistilicolous ones to stamenicolous ones, while the ancestor of the xenalocasiae complex would have retained pistilicolous habits.…”