2026 Volume 30 Pages 174-186
The Izu Peninsula of central Japan is a volcanic block that originated far to the south and was transported to its current location by the northward migration of the Philippine Sea Plate. Several small limestone bodies within the upper Lower to lower Middle Miocene volcaniclastic Yugashima Group on the Izu Peninsula contain a molluscan fossil assemblage associated with coral reefs. This assemblage provides insights into the shallow-water diversity of tropical oceanic islands on the eastern margin of the Philippine Sea Plate during the Miocene. Here, a new species of patellid limpet, Scutellastra kadotai sp. nov., is described based on specimens from the Makinoko Limestone in the Shuzenji area of the Izu Peninsula. This new species is distinct from Scutellastra mizunamiensis and Scutellastra itoigawai from contemporaneous strata in the Mizunami and Chichibu basins on the Honshu Arc of mainland Japan. The molluscan assemblage of the upper Lower to lower Middle Miocene limestone bodies on the Izu Peninsula differs in species composition from those of the nearly contemporaneous Kadonosawa/Moniwa faunas of the Honshu Arc. The discovery of a new Scutellastra species provides additional evidence that the late Early to early Middle Miocene fauna of the Izu Peninsula was distinct from those of the Honshu Arc. We propose the new faunal name “Yugashima Fauna” for the molluscan assemblage found within the limestone bodies of the Yugashima Group and discuss its paleobiogeographic significance.
ZooBank registration: urn:lsid:zoobank.org:pub:F6DEB4AA-87AE-4E86-B32A-B146DD60DB7F
Transactions and proceedings of the Palaeontological Society of Japan
Transactions and proceedings of the Paleontological Society of Japan. New series
