Species Delimitation and Description of n. sp. (Nematoda: Criconematidae), a Morphologically Cryptic, Parthenogenetic Species from North American Grasslands.

Nematode surveys of North American grasslands conducted from 2010 to 2015 frequently recovered a species of criconematid nematode morphologically resembling . These specimens were recovered from remnant native prairies in the central tallgrass ecoregion of North America, and not from surrounding agroecosystems. Historical records indicate that is a cosmopolitan species feeding on a wide range of agronomic and native plants. DNA barcoding indicates North American grasslands contain at least 10 phylogenetically distinct lineages of that resemble, but are not, . Analysis of the two most common lineages reveals two distinctly different population structures. The variation in population structure suggests unique evolutionary histories associated with their diversification. These two major lineages share a sympatric distribution and their slight morphological differences contrast with a high level of genetic separation. Based on their genetic divergence, fixed diagnostic nucleotides, population structure, species delimitation metrics, and a sympatric distribution, we believe that one of these distinct lineages warrants formal nomenclatural recognition. Herein, we provide formal recognition for n. sp. and discuss its relationship to other lineages discovered in native North American grasslands.