Silurian rugose corals from the Kurosegawa Terrane, southwest Japan, and the first occurrence of Neobrachyelasma

Four species of rugose corals (one new) are described from the Silurian of the Kurosegawa Terrane, Southwest Japan. They are Neobrachyelasma japonica n. sp., Pseudamplexus sp., Amsdenoides sp., and Amplexoides sp. aff. A. chaoi (Grabau, 1925). These species occur in the Middle Member of the Gionyama Formation, which is Late Llandovery to Early Ludlow in age. Neobrachyelasma is reported for the first time from Japan. This genus occurs in the Lower Llandovery to Upper Silurian of Japan, South China, Kazakhstan, and the Altai and might be distributed only in South China and Japan during the Late Llandovery. Its occurrence in Japan may support a paleogeographic proximity of ‘Proto-Japan’ and the South China Block during the Silurian.

Nanshanophyllum and Shensiphyllum (Silurian Rugosa) from the Kurosegawa Terrane, southwest Japan, and their paleobiogeographic implications

Three rugose species in two genera—Nanshanophyllum hamadai n. sp., N. gokasense n. sp., and Shensiphyllum sp.—are described for the first time from the Kurosegawa Terrane, Southwest Japan. These species occur in the Middle Member of the Gionyama Formation, which is Late Llandovery to Early Ludlow (Silurian) in age. The two genera, Nanshanophyllum and Shensiphyllum, formerly were known only from South China and Qaidam. The occurrence of these two genera in Japan may indicate a paleogeographic connection between ‘Proto-Japan’ and the South China Block during the Silurian.