Revision of Cypridea (non-marine Ostracoda) from the Early Cretaceous Yixian Formation of the Beipiao–Yixian Basin in western Liaoning, northeast China

The ostracod genus Cypridea Bosquet, which ranges in age from Kimmeridgian to Lower Eocene, frequently occurs abundantly in the Jianshangou and Jinggangshan beds of the Yixian Formation in western Liaoning, northeast China. However, the diversity of species has been considerably overestimated for many years, and this has led to a series of problems concerning taxonomic subdivision and stratigraphic correlation. Based on a large quantity of fossil material and more detailed descriptions of the morphological features, all of the published species of Cypridea from the Jianshangou and Jinggangshan beds are revised in this paper. As a result, 14 species erected previously are merged into three taxa: Cypridea liaoningensis, C. jingangshanensis and C. deplecta.