Original Articles
Occurrences of the possible hybrids of Sinohyriopsis schlegelii (Martens, 1861) and Sinohyriopsis cumingii (Lea, 1852) (Bivalvia: Unionida: Unionidae) in Okayama Prefecture, western Japan
Yusuke KASHIWA, Tsukasa ABE and Hiroshi FUKUDA
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Summary Some individuals of Sinohyriopsis were found alive in a canal around the Kurashiki River flowing into Lake Kojima, southern Okayama Prefecture. Based on the shell morphology, they are regarded as possible hybrids of the introduced S. cumingii (I. Lea, 1852) and the native S. schlegelii (Martens, 1861). Because adult and juvenile individuals were found, the hybrid population is likely to be maintained in the locality. The present materials were collected in a canal with a concrete bottom and banks and gravel deposits of 5Å|10 cm in thickness at 50Å|60 cm depth. The flow velocity of water was less than 1 cm/s. An introduced population of S. schlegelii from Lake Biwa may still survive in Lake Kojima, and therefore the impact of the introduction of S. cumingii is of concern in terms of the conservation of the critically endangered S. schlegelii. |
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Key words: alien species, conservation, endangered species, freshwater mussel, habitat, introduced species, Lake Kojima, San'yo District |
A new distribution record of Tapes platyptycha Pilsbry, 1901 (Bivalvia: Veneridae) in the Oki Islands, Shimane, western Japan
Mayuko YAMADA and Hiroki ONO
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Summary In a rare venerid bivalve Tapes platyptycha Pilsbry, 1901, the northern limit of distribution in the Japan Sea has been unclear to the present time. Recently the species was found in the Oki Islands, Shimane Prefecture. This is the first occurrence record in the Prefecture and also the reliable northernmost record of the species in the Japan Sea. |
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Key words: conservation, endangered species, habitat, Japan Sea, Octopus sinensis, shell debris |
The availability and validity of Akoya akoya (Y. Hirase, 1922) (Vetigastropoda: Trochida: Calliostomatidae), with notes on the morphology of the protoconch, head-foot, radula and jaw plate
Hiroshi FUKUDA, Hitoshi IKEDA, So ISHIDA and Takuma HAGA
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Summary Akoya akoya is a deep-sea calliostomatid chiefly occurring in the Pacific ocean from central Honshu to Shikoku and the East China Sea off western Kyushu, temperate Japan. The authorship and publication year of the Latin name (originally Calliostoma akoya) have been cited as '(Kuroda in Ikebe, 1942)' in much of the literature to date. However, the name was first published in the volume 4 of Kai Chigusa by Yoichiro Hirase in 1922 with the type figure and it can be regarded as available according to Articles 11.4.3 and 12.2.7 of the International Code of Zoological Nomenclature (4th edition). It is also the oldest name and thus valid for the species. Therefore the author and year of Akoya akoya should be (Y. Hirase, 1922). The following three names are the invalid junior synonyms: Calliostoma (Calotropis) ksuzukii Ikebe, 1942; Calliostoma (Calotropis?) akoya Kuroda in Ikebe, 1942; Akoya shinayaka Habe, 1961. The morphological characters of the species have been reported only in the shell and operculum. Here we describe the protoconch, head-foot, radula and jaw plate. These characters are generally similar to those of other genera of the Calliostomatinae |
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Key words: Akoya shinayaka, Calliostoma (Calotropis?) akoya, Calliostoma (Calotropis) ksuzukii, distribution, Kai Chigusa, marine gastropods, morphology, nomenclature, taxonomy |
Turbo (Carswellena) excellens Sowerby III, 1914 (Vetigastropoda: Trochida: Turbinidae) collected from Hagi, Yamaguchi Prefecture, western Honshu, Japan, with notes on the taxonomic status of Callopomella Kira, 1959
Hiroshi FUKUDA
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Summary Turbo (Carswellena) excellens Sowerby III, 1914 was collected in Sanmi Fishing Port, Hagi, Yamaguchi Prefecture. It is the northernmost (and the easternmost in the Japan Sea) record of the species. The taxonomy, morphology and distribution of the species are reviewed. Callopomella Kira, 1959 was proposed for T. excellens by monotypy as a subgenus of Turbo Linnaeus, 1758, but the taxonomic status has been obscure to date. The taxon is pointed out to be available and regarded as the junior synonym of Carswellena Iredale, 1931 (= Euninella Cotton, 1939). |
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Key words: conservation, distribution, endangered species, endemism, Japan Sea, marine gastropods, morphology, nomenclature, taxonomy |
Occurrence records of 'Parafossarulus' manchouricus japonicus (Pilsbry, 1901) (Caenogastropoda: Truncatelloidea: Bithyniidae) from Lake Kawaguchi, Yamanashi Prefecture, Japan
Naoto SAWADA, Takumi SAITO and Hiroshi FUKUDA
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Summary A bithyniid freshwater snail 'Parafossarulus' manchouricus japonicus (Pilsbry, 1901) is critically endangered in Japan. In this study, the specimens collected in 1987, 1992, and 2021 from Lake Kawaguchi, Yamanashi Prefecture, central Honshu, were examined. No reliable literature record has been published from the Lake to the present time. The results suggest that the population of the species in the Lake has rapidly decreased since the 1990s. It has also been suggested that the species competes with non-native 'Parafossarulus' longicornis (Benson, 1842) which has been introduced from China in the 2000s. Although 'P.' m. japonicus in the Lake might be an introduced population, the conservation is needed because the population is restricted to very narrow range. |
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Key words: alien species, conservation, endangered species, freshwater snail, introduced species |
Discovery of Assiminea (?) sp. (Gastropoda: Assimineidae) from Sukumo City, Kochi Prefecture, western Japan
Toru UCHINO, Jun-ichi NUNOBE, Naoki TOKUMARU and Akihito NOMOTO
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Summary Assiminea (?) sp. (an undescribed species, Japanese name: Oiran-kawa-zansho) was found in the Matsuda River, Sukumo City, Kochi Prefecture. Hitherto, this species was recorded only from the subtropical Nansei Islands. This is the first record of the species north of temperate Kyushu. It is also the northernmost and easternmost distribution record of the species. The habitats of the species in the Matsuda River are reported in detail. The possibility of the recent extension of the northern limit of the species is also discussed. |
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Key words: Assiminea (?) yoshidayukioi, global warming, tidal flat |
Rediscovery of the endangered cave-living gastropod Cavernacmella aff. kuzuuensis (K. Suzuki, 1937) (Caenogastropoda: Truncatelloidea: Assimineidae) in Fukuoka Prefecture, western Japan, after 60 years
Yusuke KAMEI and Hiroshi FUKUDA
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Summary A species of Cavernacmella Habe, 1942 [C. aff. kuzuuensis (K. Suzuki, 1937)] was found alive in G?ya No. 1 Limestone Cave, Tagawa-shi, Fukuoka Prefecture, northern Ky?sh?. This is the rediscovery of the genus in the Prefecture after 60 years. In the genus, the majority of cave-living species is known to be endemic to each cave in Japan. Therefore the present materials are likely to be an undescribed species. |
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Key words: conservation, Kyushu, limestone cave, threatened species |
Oliva mustelina Lamarck, 1811 (Neogastropoda: Olividae) caught by casting, and the potential of fishing for collecting of molluscs
Tomoyuki NAKANO
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Summary This is a report of a neogastropod Oliva mustelina Lamarck, 1811 was caught by casting at Tanabe, Wakayama Prefecture, Japan. The potential of fishing for a method of collecting molluscs is discussed. |
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Key words: Acanthopagrus schlegelii, Charonia tritonis, fishing, polychaetes |
Amalda (Baryspira) utopica Ninomiya, 1987 (Neogastropoda: Olivoidea: Ancillariidae) collected in beach drift at Cape Sata, Kagoshima, southern Kyushu, Japan
Hiroshi FUKUDA
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Summary Amalda (Baryspira) utopica Ninomiya, 1987 is a rare ancillariid species endemic to the western coast of Ky?sh? between the Got? Islands and the ?sumi Islands. In 1973, an empty shell of the species was collected in beach drift at Cape Sata, Kagoshima Prefecture, the southern end of mainland Ky?sh?. This is the only case that the species was found in beachcombing. The distribution and depth range of the species are reviewed based on literature records. The species is assumed to live not only in bathyal zone but also in shallow subtidal zone (20-150 m in depth). |
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Key words: bathybenthic, beachcombing, conservation, distribution, East China Sea, endemism, habitat, rare gastropod species, subtidal, taxonomy |
New records of Gyraulus sp. sensu Saito, Chiba & Fukuda, 2020 (Lymnaeida: Planorbidae) from Osaka, Japan, with assessment of diagnostic characters of the species
Yuji BABA and Takeru UECHI
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Summary The endangered species Gyraulus sp. sensu Saito, Chiba & Fukuda, 2020 was found in Osaka Prefecture, specifically at five sites in three municipalities: three sites in Nose-cho, one site in Ikeda-shi, and one site in Kishiwada-shi. This species was found in rice paddies, abandoned fields, and ditches. However, two habitats have already been lost due to the start of field cultivation. This implies that the species has become extinct in some areas. Monitoring of habitat and search for new habitat are desirable in future. In addition, four traits in shell morphology (shell width, shell length, body whorl height without aperture, and number of whorls) are different between this species and the similar species Gyraulus chinensis (Dunker, 1848). It is desirable that these diagnostic characters will accumulate knowledge about the distribution, habitat and ecology of this species. |
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Key words: conservation, distribution, endangered species, freshwater molluscs, habitat status |
A new occurrence record of an unidentified minute euconulid (Helicida: Trochomorphoidea) inhabiting the inside of a limestone cave in Aichi Prefecture, central Honshu, Japan
Kohei Kawamura and Yoshimasa Hayase
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Summary An unidentified species of the Euconulidae was found alive in the limestone cave 'Suse no Ja-ana' in Suse, Toyohashi-shi, Aichi Prefecture. In this species the whole head-foot is colourless and the eye is lacking black pigmentation. The species is the second example of cave-living euconulid species group after the record of a similar species from a cave in central Okinawa Island. Because the occurrence records of live individuals of this group have been little known in Japan, the situation of discovery, the habitat condition and the morphological characters of the species are reported. |
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Key words: land snail, troglodytic animal, Euconulidae, Pulmonata |
Records of Euhadra decorata (Pilsbry & Y. Hirase, 1903) and Meghimatium sp. (Gastropoda: Helicida) from Kami-machi, Miyagi Prefecture, northern Honshu, Japan
Daishi YAMAZAKI and Shun ITO
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Summary Euhadra decorata (Pilsbry & Y. Hirase, 1903) sensu stricto and an unidentified species of Meghimatium van Hasselt, 1824 are recorded from Kami-machi in Miyagi Prefecture at the T?hoku District, northern Honsh?. In the present individual of E. decorata, the shell was large in size and the dorsal head-foot was jet black in colour. It is identical morphologically with those described as E. tobai S. Hirase, 1929 which is now regarded as a form of E. decorata. Meghimatium sp. is similar to another undescribed species (Hanatate-yama-namekuji in Japanese) which has been known in Niigata Prefecture and they are likely to be conspecific or at least closely allied to each other. The present records on these two species would be important to confirm not only their own distribution ranges but also the land snail fauna of the mountainside in Miyagi Prefecture since it is still poorly understood. |
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Key words: biogeography, distribution, land snail, Pulmonata, Tohoku District |
Diagnosis, distribution and habitat of undescribed threatened molluscan species of Japan
Keiji IWASAKI, So ISHIDA, Sho KASHIO, Yuichi KAMEDA, Hirofumi KUBO, Takumi SAITO, Naoto SAWADA, Takuma HAGA, Yoshimasa HAYASE, Takahiro HIRANO and Hiroshi FUKUDA
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Summary To aid in further understanding undescribed molluscan species of Japan and biodiversity conservation, their diagnoses, distributions and habitats of 116 undescribed/unidentified threatened species (12 bivalves and 104 gastropods) are reviewed, and the synonymies of these species are provided in detail. The necessity and importance of Japanese vernacular names (wamei) for undescribed species are addressed in terms of recognising the species entity and the conservation of threatened species. New Japanese names are given for the following sixteen taxa: Shusu-shiogama for Diplodonta sp., Amami-yama-kisago for Aphanoconia sp. A, Tokara-yama-kisago for A. sp. B, Dokutsu-nobue-gai for Nobuea sp. B, Sekigahara-goma-oka-chigusa for Cavernacmella sp. F, Oko-goma-oka-chigusa for Cavernacmella sp. G, Taki-chigusa for Solenomphala sp., Atsumi-shibuki-tsubo for Fukuia sp., Iriomote-miyairi-gai for Oncomelania hupensis subsp., Tanuki-no-mushiro for Nassarius cf. elegantissimus Shuto, 1969, Juroku-keshi-gai for Carychium sp., Irabu-kiseru-modoki for Luchuena sp. B, Hishage-kibi-gai for Gastrodontella sp., Aparagi-bekko for Helicarionidae gen. & sp., Toshidon-namekuji for Meghimatium sp. B, and Hitorikko-namekuji for M. sp. C. |
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Key words: biodiversity, conservation, endangered species, Japanese name, molluscs, morphology, red data book, taxonomy |