著者

友国 雅章

出版者

国立科学博物館

雑誌

国立科学博物館専報 (ISSN:00824755)

巻号頁・発行日

vol.18, pp.153-161, 1985

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The heteropterous fauna of the Oki Islands lying far-off the Shimane Peninsula, western Honshu, Japan, has been poorly known up to the present. Eighty-six species of Heteroptera from there are listed in the present paper. Of these, 38 are newly recorded from the Islands based on the materials collected by the author's research made in 1984. These 86 species excepting Orius sp. are classified into the following five groups according to the difference in their distributional patterns as shown in the author's papers (TOMOKUNI, 1979,1981). Group 1 contains 18 species of the Oriental origin such as Macroscytus subaeneus. Scotinophara lurida, Nezara antennata, Plautia crossota stali, Leptocorisa chinensis and so on. Of these, Gardena melinarthrum is the most typical species of this group. As far as the author knows, this rare reduviid has been known only from Kyushu in Japan. Group 2 is predominant in the heteropterous fauna of the Islands. It consists of 36 species, that is Megacopta punctatissima, Poecilocoris lewisi, Halyomorpha mista, Homoeocerus unipunctatus, Piocoris varius and so on, distributed within the southern area of the Palearctic Region. Group 3 includes 24 species, whose ranges are limited within the northern part of the Palearctic Region, such as Legnotus triguttulus, Graphosoma rubrolineatum, Dybowskyia reticulata, Carbula humerigera and so no. One of the representatives of this group is Saldula scotica which dwells on the surfaces of large dry stones exposed in mountain streams. The heteropterous fauna of the Islands is comparatively rich in this group considering their low elevation. This seems to be attributed to the richness of vegetation. The 6 species, Nysius plebejus, Acalypta sauteri, Stephanitis takeyai, Amphiareus obscuriceps, Lygocoris (Apolygus) nigritulus and Gerris (Gerris) yasumatsui, are discriminated from the others as Group 4. Though they are endemic to Japan, all of them seem to be of Palearctic origin. Group 5 includes only one widespread species, Zicrona caerulea. The heteropterous fauna of the Oki Islands is rather poor, and most of the known species are common and widely distributed in the other areas of Japan. The following two reasons can be pointed out for this : 1) The area of the Islands is small (348 km^2), 2) The Islands were covered by volcanic products from the end of the Tertiary to the beginning of the Quaternary, though they were isolated on the Sea of Japan at the middle of the Miocene. It is, however, worth noticing that two apterous species, Acalypta sauteri and Schidium marcidum, are distributed on the Islands. The problem when and how the ancestors of these species immigrated in the Islands should be carefully elucidated on the basis of more adequate data than are now at hand.