New cheilostome bryozoans from the Middle Miocene of Hokkaido, Japan, and the first fossil occurrences of Kubaninella and Hayamiellina gen. nov.

Abstract

Three new species and one new genus of cheilostome Bryozoa are described from the Kaigarabashi Sandstone Beds (Kunnui Formation, late Middle Miocene) of southwestern Hokkaido. These are Hayamiettina constans (Cribrilinidae), Integripelta sakagamii (Eurystomellidae), and Kubaninella miocenica (Adeonidae). Monotypic Hayamiellina gen. nov. is also reported living at shelf depths off the Commander Islands, Bering Sea, and in the Gulf of Alaska. The finding of K. miocenica constitutes the first fossil record of the formerly monotypic genus Kubaninella. These new records, from a locality previouslysampled for Bryozoa, underscore the inadequate level of sampling and taxonomic work on the evidently biodiverse and highly endemic bryozoan fauna of the Japanese Cenozoic.