Descriptions of Three Cheilostomatid Bryozoan Species from the Continental Shelf off Boso Peninsula, Japan

Abstract

Three bryozoan species are described from the continental shelf east of the Boso Peninsula, Japan. One is a new species of Tessaradoma Norman, 1869, resembling Arctic and Atlantic species. Its colony form is, however, composed of zooids facing one side. The other two are species described from Sagami Bay as Hippothoa connata Ortmann, 1890 and Diporula coronula Ortmann, 1890. The former is assigned to the genus Cribellopora Gautier, 1957, having cribellate pseudopores on the frontal wall and ooecium. The latter is provisionally placed in the genus Hippomenella Canu and Bassler, 1917. The biogeography of the genera and species groups including the three species in this study is discussed. The boreal origin of the Japanese Tessaradoma is inferred, and the two species established by Ortmann are related to the bryozoan fauna of Australia and New Zealand.