About Rana muscosa Camp, 1917
Rana muscosa, formally published by Camp in 1917, ranges from 4 to 8.9 centimetres (1.6 to 3.5 inches) in length, with females typically larger than males. Its coloration and patterning are highly variable: the base color is yellowish, brownish, or olive, overlaid with black and brown markings. The underside of the hind legs comes in different yellow hues, ranging from bright sun yellow to pale yellow, and larger individuals may show faint orange hints on their hind legs. The throat ranges in color from white to yellow, and the thighs may be light orange or yellow. Along with its overall variable coloration, the species has a dorsal pattern of dark spots that vary in both shape and size. The specific epithet muscosa comes from the Latin word meaning "mossy" or "full of moss", a reference to the species' coloration. When handled, the frog releases a defensive odor that resembles garlic. This frog inhabits mountain creeks, lakes, lakeshores, streams, and pools, and prefers sunny areas. It rarely travels far from water, and can stay underwater for very long periods of time, likely through cutaneous gas exchange. Adults are often found on rocks near shorelines. Close proximity to water is critical because the species lays its eggs either underwater attached to rocks or in shallow water. Tadpoles require a permanent water habitat for at least two years while they develop, as tadpoles can die from lack of moisture, particularly during dry summers. Rana muscosa has been recorded at elevations between approximately 1,214 and 7,546 feet (370 and 2,300 m) in California. Its suitable habitats are primarily located north of California in the Sierra Nevada, and south of California in the Transverse Ranges. The frog emerges from its wintering site shortly after snowmelt. Its breeding season starts once peak meltwater flow has passed, occurring around March through May in the southern part of its range, and as late as July in higher, more northern mountains. The time to reach breeding maturity varies from 1 to 4 years, depending on snow levels and temperature. Very cold temperatures can cause larval death. Fertilization is external, and egg clusters are secured to vegetation in flowing water, or left floating freely in still water. Juveniles may remain tadpoles for 3 to 4 years before completing metamorphosis, though this development rate varies greatly based on the area's temperature and elevation. Tadpoles are grouped into two classes: first-year tadpoles and second-year tadpoles, and metamorphosis usually occurs during the tadpole's second summer. Individuals undergoing the transition from tadpole to young frog are called metamorphs, and are classified as juveniles once they survive their first winter. The frog becomes reproductively mature after 2 years in the juvenile stage. Overall, growth and development rates are slower at higher elevations.
