著者

今泉 吉典

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.3, pp.159-176, 1970

被引用文献数

3

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Among thirteen land mammal forms known from the Tsushima Islands, ten are undoubtedly native and three are commensal. Four groups are recognized among the native forms. 1. Korean forms, which are common to Korea but not found in Hondo, the mainland of Japan, in specific level : Crocidura suaveolens shantungensis, Mogera coreana, Mustela sibirica manchurica, Prionailurus bengalensis euptilurus. 2. Forms which are common both to Korea and Hondo in specific level : Micromys minutus aokii, Martes melampus tsuensis. 3. Japanese forms, which are common to Hondo in specific level, but not found in Korea : Apodemus navigator tusimaensis, Apodemus argenteus sagax. 4. Endemic species : Urotrichus adversus, Cervus pulchellus. Any taxonomic differences have never been discovered between specimens of the "Korean forms" and those from Korea. This may suggest that the Tsushimas had a land connection with Korea not in so remote past. The forms belonging to the second group seem to be intermediate between Korean and Japanese forms in subspecific level. "Japanese forms" evidently differ subspecifically or specifically from those of Kyushu, which are in the nearest districts of Hondo from the Tsushima Islands. Lineages, or phylogenetic branches, within Urotrichus were tried to be detected by statistical comparison of relative sizes between several local populations and a cline of well established form, U. hondonis (Figs. 1-5). By those clinal analysis, based on the author's taxonomic principles, at least four lineages were recognized in the group. According to sequence of expansions of forms in the past, which can be estimated by present distributions and degrees of morphological specializations or grades in strength, those lineages can be divided into classes, such as the most recent : lineage A, the next : lineage B, etc. Urotrichus adversus from Tsushima seems to belong to the lineage B, evidently older than U. talpoides of Kyushu belonging to the lineage A. Apodemus navigator tusimaensis is rather similar to navigator of Oki Is. and dorsalis of Yaku and Tane Is., which probably belong to the lineage B and are different from speciosus of Hondo belonging to the lineage A. Thus, most of the "Japanese forms" of Tsushima may not be derived from populations of Kyushu, belonging to the lineage A, but may perhaps be the relics of formerly widespread forms.