Description: Rana muscosa is 1.5 to 3.5 inches long. Its color and patterning are variable. It is yellowish, brownish, or olive with black and brown markings. Its species name muscosa is from the Latin meaning "mossy" or "full of moss", inspired by its coloration. It may have light orange or yellow thighs. When handled, the frog emits a defensive odor reminiscent of garlic.
Habitat: The habitat includes sunny riverbanks, meadow streams, isolated pools, and lake borders in the Sierra Nevada, cool rocky stream courses fed by springs and snow melt in southern California. The species seems to prefer sloping banks with rocks or vegetation to the water's edge. It has been observed that the frogs in southern California are typically found in steep gradient streams in the chaparral belt and may range into small meadow streams at higher elevations. In contrast, Sierran frogs are most abundant in high elevation lakes and slow-moving portions of streams. This frog seldom is found away from water, but it may cross upland areas in moving between summer and winter habitats. Wintering sites include areas nearshore under ledges and in deep underwater crevices
Range:Rana muscosa occurs in the southern Sierra Nevada of California and in mountains to the south in southern California. In southern California south of the Sierra Nevada, the historical range extended from Palomar Mountain in San Diego County northward and westward through the San Jacinto, San Bernardino, and San Gabriel Mountains of Riverside, San Bernardino, and Los Angeles counties; these formed four isolated clusters of montane populations. Additionally, the species occurred as an isolated cluster of populations on Breckenridge Mountain, south of the Kern River in Kern County, and in the Sierra Nevada (west of the crest) in Tulare, Inyo and Fresno counties, extending north to Mather Pass. The mountain ridges that separate the headwaters of the South Fork Kings River from the Middle Fork Kings River, from Mather Pass to the Monarch Divide, form the northern border of the range.
Rana muscosa is now extirpated on Palomar and Breckenridge mountains and in much of the former range elsewhere in southern California and the southern Sierra Nevada. In the mountains of southern California, it exists as highly isolated populations (USFWS 2012). Historical elevational range in the mountains of southern California was 1,220-7,560 feet.
Diet: This species feeds on insects such as beetles, ants, bees, wasps, flies, and dragonflies. It is also known to eat tadpoles. Adults of the Rana muscosa eat aquatic and terrestrial invertebrates and anuran larvae; availability of larval anuran prey may be an important factor in distribution, body condition, and survival of adults. Larvae eat algae, organic debris, plant tissue, and minute organisms in water.
Reproduction: Its breeding season begins once the highest meltwater flow is over, around March through May in the southern part of its range, and up to July in higher mountains to the north. Fertilization is external, and the egg cluster is secured to vegetation in a current, or in still waters sometimes left floating free. The juvenile may be a tadpole for 3 to 4 years before undergoing metamorphosis.
Status: The frog is an endangered species under the US Endangered Species Act. The International Union for Conservation of Nature has also listed it as endangered. Its NatureServe conservation status is Imperiled.
Disclaimer: ITIS taxonomy is based on the latest scientific consensus available, and is provided as a general reference source for interested parties. However, it is not a legal authority for statutory or regulatory purposes. While every effort has been made to provide the most reliable and up-to-date information available, ultimate legal requirements with respect to species are contained in provisions of treaties to which the United States is a party, wildlife statutes, regulations, and any applicable notices that have been published in the Federal Register. For further information on U.S. legal requirements with respect to protected taxa, please contact the U.S. Fish and Wildlife Service.
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