Gigantic scaphopods (Mollusca) from the Permian Akasaka Limestone, central Japan

• DOI: 10.1017/jpa.2021.3
• Publication Date: 2021-03-10T09:05:35Z
• Authors: Kaito Asato; Tomoki Kase
• Keywords: 14. Life underwater; 01 natural sciences; 0105 earth and related environmental sciences

AbstractPaleozoic scaphopods are among the most poorly known mollusks because of their featureless tubular shell morphology and fragmentary preservation. An apical orifice at the posterior end of a conch is a diagnostic character of Scaphopoda that distinguishes them from other groups of animals that produce similar calcareous tubes, but this structure is rarely preserved. A rich molluscan fauna from the Permian Akasaka Limestone in central Japan includes scaphopod shells, and past studies have reported four species, all of which were based on fragmentary specimens. This study recognizes six species in the Akasaka Limestone mainly on the basis of museum/institution collections, and a new genus (Minodentalium) and three species (Prodentalium onoi,M.hayasakai, andM.okumurai) are described, two known species (P.akasakensisandP.neornatum) are redescribed in more detail, and one species (Prodentaliumsp.) is described under open nomenclature. The following eight known species are allocated to the new genusMinodentalium:Plagioglypta furcataWaterhouse, 1980;Pl.girtyiKnight, 1940;Pl.subannulataEaston, 1962;Dentalium ingensDe Koninck, 1843;D. meekianumGeinitz, 1866;Pl.prosseriMorningstar, 1922;Dentalium priscumMünster in Goldfuss, 1842; andD.herculeumDe Koninck, 1863. All the species, except forM.hayasakai, are gigantic, reaching 200 mm or more in length. The species richness is the greatest known from a single locality/formation worldwide.UUID:http://zoobank.org/35405b9d-3ba7-40bf-87c5-3f2b550b1a6d