The Yuriyagai: J. Malacozool. Ass. Yamaguchi, 7(2). January 2000

Original Articles

Ceratia nagashima, sp. nov. (Gastropoda: Sorbeoconcha: Iravadiidae) from Tanoura, Nagashima Island, Kaminoseki-chô, Yamaguchi Prefecture, Japan 

Hiroshi FUKUDA

Abstract Ranellidae recorded from Yamaguchi Prefecture, western Honshû, are Biplex perca (Perry, 1811), Fusitriton galea Kuroda & Habe in Habe, 1961, Gyrineum natator (Röding, 1798) (new record; actually from Ehime Pref.), Charonia lampas (Linnaeus, 1758) (= sauliae Reeve, 1844; = macilenta Kuroda & Habe in Habe, 1961), Cymatium (Gelegna) succinctum (Linnaeus, 1771), C. (Gutturnium) muricinum (Röding, 1798) (new record), C. (Linatella) cingulatum (Lamarck, 1822) (= caudatum Gmelin, 1791; = cutaceum Lamarck, 1816), C. (Lotoria) grandimaculatum (Reeve, 1844) (new record), C. (Monoplex) comptum (A. Adams, 1855) (new record), C. (Monoplex) exaratum (Reeve, 1844) (= kiiense Sowerby, 1915), C. (Monoplex) mundum (Gould, 1849) (new record), C. (Monoplex) parthenopeum (von Salis Marschlins, 1793) (= echo Kira, 1959), C. (Monoplex) pileare (Linnaeus, 1758), C. (Monoplex) tenuiliratum (Lischke, 1873), C. (Ranularia) caudatum (Gmelin, 1791), C. (Ranularia) dunkeri (Lischke, 1868), C. (Ranularia) pyrum (Linnaeus, 1758), C. (Ranularia) sinense (Reeve, 1844), and C. (Turritriton) labiosum (Wood, 1828). Bursidae recorded are Bursa granularis (Röding, 1798), Bufonaria perelegans Beu, 1987 (new record), B. rana (Linnaeus, 1758) (= albivaricosa Reeve, 1844), and Tutufa (Tutufa) bufo (Röding, 1798). The one species of Personidae recorded is Distorsio reticularis (Linnaeus, 1758). This fauna is important for demonstrating the occurrence of several species on the Japan Sea and Seto Inland Sea coasts well to the north of previous records.

Key words: Ceratia nagashima, Iravadiidae, new species, anaerobic tide-pool, Kaminoseki Nuclear Power Plant, Yamaguchi Prefecture, Seto Inland Sea

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Marine molluscan and brachiopod fauna of Tanoura, Nagashima Island, Kaminoseki-chô, Yamaguchi Prefecture, Japan

Hiroshi FUKUDA, Takahiro ASAMI, Hiroyoshi YAMASHITA, Masanori SATÔ, Shigeo HORI and Yasuhiro NAKAMURA

Abstract A faunal survey of Tanoura (the proposed site of the Kaminoseki Nuclear Power Plant), Nagashima Island, Yamaguchi Prefecture, Japan in August to October 1999, recorded 183 marine molluscan and 1 brachiopod species. The following are particularly important: 1) Tomura cf. yashima, a cornirostrid gastropod, lives in an aerobic tide-pools. This species is distinguishable from T. yashima and T. himeshima in having distinct spiral cords on the shell surface, but further study is needed for definitive identification. The species at the proposed site of the nuclear power plant may be endemic to that area. 2) Ceratia nagashima H. Fukuda, 2000 (family Iravadiidae) was collected beneath stones partly buried in sand in an anaerobic tide-pool. The present site is the only known locality of this species in the world at present. 3) Discinisca sparselineata Dall, 1920, an endangered brachiopod, occurs abundantly in the intertidal zone. 4) Four species of Pyramidellidae were collected alive. Living specimens of Linopyrga sp., Kleinella sulcata A. Adams, 1862 and Pyrgulina pupula (A. Adams, 1861) were collected for the first time. 5) 11 undescribed species of a number of gastropod families (e.g. Cingulopsidae, Eatoniellidae, Rissoellidae, Omalogyridae) were contained in samples of micromolluscs collected with brown and/or calcareous algae. 6) Eight species which were cited as vulnerable or rare in WWF Japan's red data book for organisms of tidal flats in Japan live in this locality. 7) The molluscan fauna shows great diversity. The natural environment is in extremely good condition. Therefore, the present locality is thought to represent the original form of the Seto Inland Sea, which has otherwise mostly been lost. Such a situation is extremely rare in modern Japan. 8) Some species that are distributed mainly in those areas of the Pacific and Japan Sea coasts of Japan under the influence of warm currents and which have been considered very rarely or had not been recorded in the Seto Inland Sea were found. The survey locality may be the point under the strongest influence of a branch of the Kuroshio Current, which comes from the Pacific through the Bungo Strait into the Seto Inland Sea coast of Yamaguchi Prefecture. For the reasons mentioned above, the fauna and ecosystem of the present locality are considered to be extremely important. Ideally, such a significant fauna should be kept entirely intact and not subjected to any artificial actions, and should be conserved permanently for instance as a special nature preserve or sanctuary.

Key words:Tomura, Cornirostridae, Pyramidellidae, Discinisca sparselineata, rare species, conservation, Kaminoseki Nuclear Power Plant, Yamaguchi Prefecture, Seto Inland Sea

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