Diadophis punctatus

Numerous data suggest that more than one lineage exists (Blanchard 1942, Gehlbach 1974, Pinou et al. 1995, Feldman and Spicer 2006). Using mitochondrial data sampled from specimens across their range, Fontanella et al. (2008) found at least 14 lineages that do not follow the geographic range of the subspecies, and may be independently evolving taxa. While D. punctatus may be divided into several species in the near future, Crother (2017) refrain from making any changes at present. Evidence to synonymize the various races into a single species has been poorly presented, and the arrangement in Crother (2017) follows the traditional subspecies groupings.

The range extends from the Pacific coast to the Atlantic coast of North America (Conant and Collins 1991, Stebbins 2003). The northern limit of the more or less continuous portion of the range reaches Nova Scotia, southern Quebec, southern Ontario, Minnesota, southeastern South Dakota, eastern Nebraska, southeastern Colorado, and Arizona. The southern limit extends to San Luis Potosi (Mexico), the Gulf Coast of the United States, and southern Florida. The species also occurs disjunctly in western North America in eastern Washington, eastern Oregon, Idaho, Nevada, Utah, and Arizona, and it ranges from southern Washington through western Oregon and throughout much of California (except the Central Valley and deserts) into northwestern Baja California, including Islas Todos Santos and San Martin along the Pacific Coast (Grismer 2002). This species has been introduced on Grand Cayman Island (probably via ornamental plants from southern Florida), but it is unknown whether or not the species is established there (Schwartz and Henderson 1991).

This species is represented by thousands of occurrences or subpopulations.

No major threats have been identified. Many local populations have been lost or reduced as a result of habitat destruction (Ernst and Ernst 2003), but these appear to amount to a small minority of the total distribution.