List of species endemic to Mendocino County, California

This is a list of plant and animal species, subspecies and varieties that are endemic to Mendocino County, California, or to Mendocino and no more than one neighboring county.

Flora

 * Chorizanthe howellii, a flowering plant in the buckwheat family found only near Fort Bragg
 * Cuscuta pacifica var. papillata, a parasitic plant found only in the salt marshes of Mendocino county
 * Eriogonum kelloggii, a species of buckwheat found only on Red Mountain near Leggett
 * Harmonia guggolziorum, a flowering aster found in two locations near Hopland
 * Limnanthes bakeri, a meadowfarm plant known in only 20 locations near Willits
 * Pinus contorta var. bolanderi, the Mendocino shore pine tree, a variety of the more widespread lodgepole pine
 * Sedum eastwoodiae, a flower in the stonecrop family found only on Red Mountain near Ukiah

Fauna

 * Aplodontia rufa nigra (Point Arena mountain beaver), a mid-sized rodent regarded as a living fossil and found only near Point Arena
 * Opercularia ampluscolonia, a protist that inhabits ponds in Mendocino County
 * Plebejus idas lotis (Lotis blue butterfly), a possibly extinct gossamer-winged butterfly last recorded near Mendocino town in 1983
 * Speyeria zerene behrensii (Behrens' silverspot butterfly), found only near Point Arena

Mendocino County and one adjacent county
In addition, the following are endemic to an area contained in Mendocino and only one neighboring county:

Flora

 * Arctostaphylos mendocinoensis, a species of manzanita found only in Mendocino and Sonoma counties
 * Astragalus agnicidus, a species of milkvetch found only in Mendocino and Humboldt counties
 * Cupressus pygmaea, a species of cypress tree found only in Mendocino and Sonoma counties
 * Lewisia stebbinsii, a flowering purslane found only in Mendocino and Trinity counties
 * Veratrum fimbriatum, the fringed corn lily, a relative of the lily found only in Mendocino and Sonoma counties

Fauna

 * Helminthoglypta arrosa pomoensis, the Pomo Bronze Shoulderband, a 39 mm land snail found in redwood forests in Mendocino County (in the Big River, Navarro River, and Russian Gulch watersheds) and Sonoma County