The species was named in honor of Silas Weir Mitchell (1829–1914), an American medical doctor who also studied rattlesnake venoms.

The race on Isla Ángel de la Guarda is known to become larger, the maximum recorded length for a specimen there being 136.7 cm (53.8 in).

In contrast, the population on El Muerto Island only reaches a maximum of 63.7 cm (25.1 in) in length.

[2] Grismer (1999) argued that C. m. angelensis and C. m. muertensis should be given species status, mainly due to differences in body size.

stephensi as a full species, and Meik et al. (2015) [11] elevated both the southwestern and the Angel de la Guarda speckled rattlesnakes to the state of full species, C. pyrrhus and C. angelensis, whereas the El Muerto Island speckled rattlesnake was considered part of C. pyrrhus The nominate subspecies (C. m. mitchellii ) is classified as "Least Concern" on the IUCN Red List of Threatened Species.