Yezopollis mikasaensis gen. et sp. nov., a new Normapolles-type angiosperm pollen from the Upper Cretaceous of Hokkaido, Japan

Abstract

A new taxon, Yezopollis mikasaensis gen. et sp. nov., is described based on Normapolles-type angiosperm pollen grains obtained from the upper Cenomanian–lower Turonian Mikasa Formation of the Yezo Group outcropping in Mikasa City, central Hokkaido, Japan. The grains are triangular to subcircular, with three or sometimes four equatorial apertures that are thickened and slightly protruding, and externally extended into a vertical slit. The surface is coarsely reticulate with a marked broad, psilate zone at the aperture margin. They are morphologically most similar to Siberiapollis within the Normapolles complex, but are distinct in their rounder outline and vermiculate reticulum. Yezopollis adds a new record of this group, which is markedly different from other genera of the same age, and is the earliest Normapolles-type representative found outside of the province. Yezopollis mikasaensis was the sole angiosperm pollen contained in a leaflitter bed exclusively composed of the platanoid Ettingshausenia cuneifolia. Ettingshausenia-type leaves are found in Menispermaceae and Platanaceaeas which diverge at the base of all eudicots, as well as in Hamamelidaceae of the basalmost superrosids. Yezopollis-type pollen has not been reported for these families, but is usually reported in Proteaceae of the basal eudicots. The co-occurrence of Y. mikasaensis and E. cuneifolia might imply that some early eudicots exhibited intermixed features of extant basal eudicot families if they were shed by the same plant species.