ABSTRACT: Cypridea Bosquet 1852 (Cypridoidea, Cyprideidae) is a Kimmeridgian to Lower Eocene nonmarine ostracod genus, the representatives of which are very common and stratigraphically useful in Late Tithonian to earliest Barremian “Purbeck/Wealden-likeâ€ nonmarine deposits of the world. The revision of particularly North American representatives led to progress in its taxonomy, and a breakthrough in its biostratigraphic supraregional biostratigraphic application. Key to their successful application is an upgraded taxonomic concept including new insights into the coherences of specific reproductive mechanisms (asexual and mixed reproduction) in the context with diversity and dispersal modes, combined with the understanding and evidence that these ostracods are not as endemic as erstwhile believed. This taxonomic concept resolves crucial problems resulting from an overestimation of the taxonomic significance of several carapace characters (particularly ornamentation elements and the outline), and facilitates improved stratigraphic and paleoecologic applications as well as providing the basis for further research. The revision includes an extensive historic overview of most relevant publications. Representatives of Cypridea have great utility in improving the biostratigraphic age determination for and correlation of Early Cretaceous formations of the Western Interior foreland basin. With respect to suprageneric taxonomy, the family Cyprideidae Martin 1940 is partially revised as well. Longispinella Sohn 1979 is now considered a subgenus of Cypridea while Cypridea (Guangdongia) Guan 1978 is allocated to Bisulcocypridea Sohn 1969, and the genus Praecypridea Sames, Whatley and Schudack 2010(b) is included. The genus Cypridea is emended anew. As for the subgeneric taxonomy, the North American species Cypridea (Pseudocypridina) inornata (Peck 1951) is now considered a junior synonym of Cypridea (P.) setina (Anderson 1939), Cypridea (P.) laeli Sohn 1979 considered an ecophenotype of Cypridea (P.) piedmonti (Roth 1933), and Cypridea (Longispinella) asymmetrica Sohn 1979 designated synonymous (sexual dimorph) to C. (L.) longispina Peck 1941. Sexual dimorphism is presumed in several species of Cypridea and mixed reproduction corroborated as being the most likely reproductive mechanism among taxa of this genus. Cypridea? minuta (Peck 1951) most probably represents an early representative of the sulcate Bisulcocypridea Sohn. Ostracod correlations mainly based on representatives of Cypridea strongly suggest a much higher maximum age for some Lower Cretaceous formations (Lakota Formation, South Dakota and Wyoming, and Cedar Mountain Formation, Utah) of the Western Interior foreland basin, i.e., Berriasian to Early Valanginian instead of Barremian or Aptian.
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