Species of the genus Cypridea Bosquet, 1852 (Ostracoda) from the Lower Cretaceous Yixian and Jiufotang formations of western Liaoning, China

Based on newly collected material from the Lower Cretaceous (Hauterivian to Aptian) Yixian and Jiufotang formations of the Jehol Group, eight Cypridea species have been recognized in western Liaoning: C. ganzhaoensis, C. gujialingensis n. sp., C. jiufotangensis, C. vitimensis, C. beipiaoensis, C. subfracta, C. subelongata, and C. semiovata. Among them, one species from Kazuo area is new, Cypridea gujialingensis n. sp. Except for C. vitimensis, which has also been reported from Mongolia and western Siberia, the rest of the species are endemic to western Liaoning. On the basis of new material, we confirm sexual dimorphism in C. vitimensis and distinguish sexual and parthenogenetic populations. Paleobiologically, we infer a mixed reproduction mode for C. vitimensis and suggest that its sexual populations from western Liaoning could indicate stressful environmental conditions.