Invasive virile crayfish (Faxonius virilis Hagen, 1870) hybridizes with native spothanded crayfish (Faxonius punctimanus Creaser, 1933) in the current river watershed of Missouri, U.S.
Crayfishes are a diverse group of freshwater crustaceans which have proven to be harmful invasive species and are a leading cause of displacement of native crayfishes. Invasive species can harm populations of native species through hybridization which facilitates the displacement of native species and leads to a decrease in diversity. Hybridization has rarely been documented between crayfish species and the only genetically documented reports of North American crayfish species hybridizing have been between invasive rusty crayfish (Faxonius rusticus Girard, 1852) and two congeners. Virile crayfish (Faxonius virilis Hagen, 1870) is the most widely distributed crayfish in North America and occurs in its native range from the Hudson Bay watershed in Canada south to across the midwestern United States. Faxonius virilis has been introduced throughout North America and parts of Europe and is considered invasive in many locations. Faxonius virilis is invasive in the Ozark National Scenic Riverways (ONSR) in Missouri, U.S., and has been detected in the park since 1986. Setting out to document an updated range of F. virilis in the ONSR, we began developing a F. virilis-specific eDNA assay and noticed a discordance between the phenotype and mitochondrial DNA barcode of some native spothanded crayfish (Faxonius punctimanus Creaser, 1933) specimens. We compared mitochondrial, phenotypic, and microsatellite data and found that invasive F. virilis have hybridized with native F. punctimanus in the ONSR. Our research adds to the rarely documented occurrences of crayfish hybridization and supports previous researchers' remarks that undocumented hybridization between native and nonnative crayfish may be more common than previously thought. While the invasion of F. virilis has had a genetic impact on a native crayfish, the long-term evolutionary consequences are unknown.