Despite the intensive use of the Leptopilina genus and its drosophilid hosts as model-systems in the study of host-parasitoid interactions, the diversity and distribution of the species occurring in the Asian region remain elusive. Here we report the phylogeny of Japanese Leptopilina species attacking frugivorous drosophilid flies, japonica occurring in Japan, and L. j. formosana occurring in Taiwan. According to these results, we discuss the evolution, speciation and colonization history of Japanese Leptopilina species.
The phylogeny of Colocasiomyia (Drosophilidae) is analysed using data for 70 morphological characters, many of which are re‐evaluated from or added to those used previously, for an expanded taxon sample of 24 Colocasiomyia ingroup species. A special focus is put on three species, of which two have remained unresolved for their relationships to other Colocasiomyia species, and the other is a newly discovered species. The analysis results in a single, most parsimonious cladogram, in which a clade comprising the three focal species is recognized along with other clades recovered for the known species groups of Colocasiomyia. Based on this, a new species group—the gigantea group—is established, including Colocasiomyia gigantea (Okada), C. rhaphidophorae Gao & Toda, n.sp. and C. scindapsae Fartyal & Toda, n.sp. These species of the gigantea group breed on inflorescences/infructescences of the subfamily Monsteroideae (Araceae) exceptionally among Colocasiomyia species, most of which use plants of the subfamily Aroideae as their hosts. Colocasiomyia gigantea uses Epipremnum pinnatum (L.) Engler, C. rhaphidophorae uses Rhaphidophora hookeri Schott and C. scindapsae uses Scindapsus coriaceus Engler as their hosts. The host plants of the gigantea group are epiphytes and differ in the structure of spadix and the fruiting process from those of the Aroideae. To understand how the species of the gigantea group adapt to properties of their host plants, their reproductive ecology—most intensively that of C. gigantea—is investigated. The lifecycle of C. gigantea is characterized by its relatively slow embryonic development (taking approximately 6 days), the very long duration of the full‐grown first instar within the egg capsule (approximately three months) until dehiscence of host infructescence, and its relatively fast larval and pupal development (taking approximately 11 or 12 days). Some morphological adaptations and the reproductive strategy in terms of ‘egg size vs. number’ trade‐off are discussed in relation to their reproductive habits and peculiar lifecycles.
The diversity, abundance and association of frugivorous drosophilids and their parasitoids were studied in Bogor, Indonesia (the tropical region), and compared with the results in Iriomote-jima (the subtropical region) and Tokyo (the temperate region).In the collections of adult drosophilid flies by traps baited with banana in wooded areas, the number of commonly observed frugivorous drosophilid species (i.e. species that occupied more than 0.5% of total drosophilid samples) was 10 in Bogor and nine in Iriomote-jima, more than in Tokyo (six species), probably reflecting the high diversity and abundance of fruits. The rate of parasitism was very high in Bogor, especially in species of the Drosophila ananassae and immigrans species groups. The diversity of parasitoids attacking frugivorous drosophilids was higher in Bogor and Iriomote-jima than in Tokyo, possibly due to the high species diversity of host drosophilids.Parasitoids generally showed wider latitudinal distributions than drosophilids. No remarkable difference was observed in the host range among tropical, subtropical and temperate parasitoids.
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.
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