Tetracyclus chankaicus, a new species from Miocene sediments of the Khanka Lake, Primorye, Russia

Abstract

A new species Tetracyclus chankaicus Dubrovina, Usoltseva, Pushkar & Likhacheva is described from Middle Miocene sediments of the Novokachalinskaya formation on the western coast of Khanka Lake in Primorye, Russian Far East. This species differs from T. clypeus (Ehrenberg) Li by the irregular stria density on the valve face, the absence of secondary ribs at the poles, different girdle band structure and the number of rimoportulae.

Keywords:

• girdle bands
• Khanka Lake
• Miocene sediments
• rimoportulae
• secondary ribs
• Tetracyclus chankaicus

Acknowledgements

This work was carried out as part of the project no. VI.50.1 in the Electron Microscopy Center of Collective Instrumental Center ‘Ultra microanalysis’ at the Limnological Institute of the Siberian Branch of the Russian Academy of Sciences and project no. 12-05-33007 funded by the Russian Fund for Fundamental Research. We would like to thank Yelena Likhoshway, David Williams, Galina Khursevich, Patrick Kociolek, Maksim Kulikovskiy and Galina Pomazkina for their advice, David Jewson, Marina Potapova and Il'dar Gabaev for correcting the English, two anonymous reviewers for commenting and improving the paper, and Victor Egorov for his assistance during the work on SEM.