著者

吉田 匠 竹中 將起 東城 幸治

出版者

Entomological Society of Japan

雑誌

昆蟲.ニューシリーズ (ISSN:13438794)

巻号頁・発行日

vol.26, no.3, pp.165-174, 2023-09-25 (Released:2023-10-17)

参考文献数

26

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Elmomorphus beetles were recorded for the first time on Okinoerabu-jima Island in the Ryukyu Archipelago. Morphological examinations of the specimens clearly identified them as being Elmomorphus amamiensis. To date, based on the results of morphological classification and molecular phylogenetic analyses, two Japanese Elmomorphus beetles have been recorded; namely, Elmomorphus brevicornis and E. amamiensis. However, a third lineage was detected among them based on our genetic analyses. This third lineage was identified as being within the E. amamiensis populations of the Okinawa-jima and Kume-jima Islands and also in the Okinoerabu-jima Island populations and was newly discovered in this study. According to the analyses of all their nuclear and mitochondrial DNA, this third lineage did not constitute a monophyletic group with E. amamiensis of Amami-oshima Island (which is the type locality of this species), but rather formed a monophyletic group with E. brevicornis. These results suggested the following two possibilities: 1) the existence of a third distinct species, different from the other two species, 2) all three lineages together constitute one species as a whole and each lineage corresponds to a regional sub-clade within that species. In addition, the morphological characteristics that have been used to distinguish species/subspecies may themselves be problematic. Although it is not possible to come to a definitive conclusion as to which hypothesis is correct in this study, it has become clear that Elmomorphus beetles are an extremely significant species in discussions about the origin and phylogeographic history of the Ryukyu Archipelago.

著者

吉田 匠 野田 聖 東城 幸治 竹中 將起

出版者

一般社団法人 日本昆虫学会

雑誌

昆蟲.ニューシリーズ (ISSN:13438794)

巻号頁・発行日

vol.26, no.2, pp.107-114, 2023-06-25 (Released:2023-06-28)

参考文献数

17

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甑島列島は九州南西部に位置し,上甑島,中甑島,下甑島とそれらの周辺の小さな島々から成る.甑島列島は,最終氷期に形成された陸橋により九州島と接続したとされるが,多くの固有種が報告されている.これは,甑島列島において独自の生物相が形成されてきたためと考えられる.しかし,甑島列島では水生昆虫類の報告は少なく,本研究で着目したカゲロウ類に関する報告はない.そこで,甑島列島に生息するカゲロウ目昆虫を調査した.その結果,4科(Baetidae, Ephemeridae, Heptageniidae, Dipteromimidae)にわたる少なくとも5属7種のカゲロウ目昆虫を採集した(属種の同定ができなかったコカゲロウ科がBaetis属以外であれば6属となる).また,採集した甑島列島のカゲロウ類はすべて九州島との共通種であり,上甑島と下甑島で採集したカゲロウ相に違いはなかった.本報は,甑島列島におけるカゲロウ目昆虫類の最初の記録である.