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International Journal on Algae
SJR: 0.219 SNIP: 0.261 CiteScore™: 0.24

ISSN Print: 1521-9429
ISSN Online: 1940-4328

International Journal on Algae

DOI: 10.1615/InterJAlgae.v3.i1.100
pages 86-98

Valve ultrastructure of new and rare fossil freshwater species of Thalassiosira Cl. (Bacillariophyta) from China and USA

J. P. Kociolek
Diatom Collection, California Academy of Sciences, Golden Gate Park, San Francisco CA 94118, USA
O. K. Khursevich
Institute of Geological Sciences, National Academy of Sciences of Belarus, 7, Kuprevich St.. 220141 Minsk, Belarus


Three small new species of the genus Thalassiosira Cl. (T. yunnaniana Khursevich & Kocioiek, T. bradburyi Khwsevieh & Kocioiek and T. iraidae Khursevich & Kocioiek) studied in light and scanning electron microscope are described from the Miocene freshwater deposits in Yunnan Province, China. All studied species have internal flat cribra covering individual loculate areolae on the valve surface. Moreover, an expanded diagnosis of T. kilarskii Kaczmarska known from the Miocene diatomites of western USA is also presented. Unlike the Chinese species, T. kilarskii has areolae with internal radial zigzag paths of continuous cribra. Also, the presence of valve face faltoportulae is reported in this species, a characteristic described as lacking in the original description.