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

Abstract

Four species of rugose corals (one new) are described from the Silurian of the Kurosegawa Terrane, Southwest Japan. They areNeobrachyelasma japonican. sp.,Pseudamplexussp.,Amsdenoidessp., andAmplexoidessp. 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.Neobrachyelasmais 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.