Fauna and biogeography of harvestmen (Arachnida: Opiliones) of the Oki Islands, Japan

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We investigated opilionid fauna of the Oki Islands (Shimane Prefecture) in the Sea of Japan for the first time. As a result, a total of 14 species were collected from the four main islands (12, 4, 4, and 6 species from Is. Dôgo, Is. Nakanoshima, Is. Nishinoshima, and Is. Chiburi, respectively). A list of the species with some taxonomical notes is presented. Opilionid fauna of the islands may be characterized by: 1) the absence of some species which are commonly found in the San'in area of the mainland Honshu such as <i>Gagrellula ferruginea</i> Loman, and <i>Nelima satoi</i> Suzuki; 2) occurrence of some species that indicate the circum-Japan Sea distribution, such as <i>Leiobunum rubrum</i> Suzuki and <i>Melanopa grandis</i> Roewer; 3) occurrence of some species showing geographical differentiation, though there are no endemic forms at the species level; and 4) affinity to the mainland area around Mt. Daisen (Tottori Pref.) rather than mainland areas of the Shimane Prefecture in the species composition; 5) The numbers of species found on the islands generally exceed those expected from the species-area relationship in and around Japanese Islands. <i>Leiobunum wegneri</i> Šilhavý 1976 described from North Korea is newly synonymized with <i>Leiobunum japonicum japonicum</i> Müller 1914. Likewise, <i>Metagagrella damila</i> Šilhavý 1976 and <i>Gagrella crassitarsi</i> Ha et al. 2004, both originally described from Korean Peninsula, are synonymized with <i>Melanopa grandis</i> Roewer 1910. Two Korean species recently recorded under the names <i>Leiobunum rotundum</i> (Latreille 1798) and <i>Leiobunum rupestre</i> (Herbst 1799) by Ha et al. (2004, Korean Arachnology, 20: 53-71) from Korea are misidentifications of <i>Leiobunum japonicum japonicum</i> and <i>Odiellus aspersus</i> (Karsch 1881), respectively.


  • Acta Arachnologica

    Acta Arachnologica 54(1), 51-63, 2005

    Arachnological Society of Japan


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