Microtus californiens (Peale, 1848) . Mammalia in Repts. U.S. Expl. Surv., 8:46.

TYPE LOCALITY: USA, California, Santa Clara Co., vicinity of San Francisco Bay, San Francisquito Creek near Palo Alto (as fixed by Kellogg, 1918:5) .

DISTRIBUTION: Oak woodlands and grasslands of Pacific coast, from SW Oregon through California, USA, to N Baja California, Mexico.

STATUS: U.S. ESA and IUCN - Endangered as M. c. scirpensis .

SYNONYMS: aequivocatus, aestuarinus, constrictus, edax, eximius, grinnelli, halophilus, huperuthrus, kernensis, mariposae, mohavensis, neglectus, paludicola, perplexibilis, sanctidiegi, sanpabloensis, scirpensis, stephensi, trowbridgii, vallicola.

COMMENTS: Broadly affiliated with other North American species of Microtus, but evidence for nearest specific relative contradictory (compare assessments of Anderson, 1959; Hooper and Hart, 1962; Moore and Janecek, 1990). Zagorodnyuk (1990) acknowledged enigmatic phyletic stature as sole member of californicus species group, subgenus Mynomes . Geographic races delineated by Kellogg (1918); Gill (1980) recorded instances of sterility in hybrids between M. c. californicus and M. c. stephensi .