ELLIPTICAL SPECIES OF THE FRESHWATER GENUS AULACOSEIRA IN MIOCENE SEDIMENTS FROM YAMATO RISE (SEA OF JAPAN)

Abstract

Elliptical valves of diatoms of the genus Aulacoseira Thwaites from Miocene deposits of different elevations of the underwater Yamato Rise were studied with light and scanning electron microscopy. Peculiar characteristics of areolar density, shapes of spines and rimoportulae and their location were shown. A new species A. ovata Usoltseva & Tsoy sp. nov. from sediments of the northeastern slope of Takuyo Bank was described. An extended description of Aulacoseira elliptica Tsoy emend. Usoltseva from sediments of the southern elevation Yamato was given.

Keywords:

• elliptical Aulacoseira
• Aulacoseira ovata
• Aulacoseira elliptica
• Miocene
• Takuyo Bank
• Yamato Bank
• Yamato Rise
• the Sea of Japan