Polytypic species and hybridization in quaternary freshwater ostracods of North America
Abstract Quaternary fresh-water ostracods of nominal species Candona patzcuaro and C. rawsoni (each including several synonyms) are considered to belong to a single, polytypic species on the basis of geographic distribution and hybridization evident in faunas from Missouri. Data are insufficient to permit designation of subspecies. “C. patzcuaro” and “C. rawsoni” thus are treated informally, as phena. Occurrences of these phena in North America indicate shifting of ranges and secondary intergradation at middle latitudes which can be correlated broadly with glacial advances and retreates and associated climatic change.