| 概要 |
Phylogenetic analysis of members of Bagous known to occur in Japan was performed to produce an hypothesis about the phylogenetic relationships of the 17 species. Both manual and computer-aided reconst...ructions were performed. On the basis of this analysis, eight species groups were recognized, the B. pygmaeus group (including B. minor and B. pygmaeodes), the B. bipunctatus group (including B. kagiashi, B. ryukyuensis, B. occultus, B. spiculatus, B. bipunctatus and B. subcordatus), the B. fractus group (including B. fructus), the B. frit group (including B. fritodes), the B. transversus group (including B. youngi), the B. rotundatus group (including B. rotundatus), the B. buckinghami group (including B. buckinghami), and the B. proprius group (including B. proprius). The hypothesis of phylogeny compared well with a previous analysis of Australian species of the genus and integrated well with it. Combining Australian and Japanese species in the analysis did not significantly alter topology of branches. Thus, relationships of species and groups of species as determined independently for species of each of these geographically separated faunas is corroborated. This concordance indicates that phylogenetic analysis based on a subset of members of a taxon, while excluding the majority of its members, can be a valuable tool in development of a classification. Several species are known only from females and therefore cannot be confidently assigned to species groups: B. lewisi, B. subvirtarus, and B. tuberculosus. On the basis ‘of characters used for analysis, placement in relation to known species is equivocal because these species share homoplastic characters with several other species which are not closely related to each other. These species are placed in an uncertain position among Japanese Bagous. Also known only from females, B. subcordatus has genitalia rather similar to certain species in the B. bipunctatus group, and is tentatively assigned to that group as most closely related to B. bipunctatus. Species known only from male specimens (B. occultus and B. rotundatus) can be confidently placed phylogenetically because many of the important, phylogenetically useful characters are found in male genitalia. The Japanese Bagous constitute a diverse assemblage of species whose closest relatives occur in Southeast Asia, North America, or in the Palearctic Region. Several species groups represented in Japan are monobasic, but we fully expect that each is closely related to other, non-Japanese species with which we are unfamiliar at this time. Computer analysis using PAUP agrees closely with manual reconstruction of relationships; differences are due to the more conservative, compromising hypothesis presented. Manual reconstructions tend to be most similar to 50% majority-rule consensus trees.続きを見る
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