Rana muscosa Camp, 1917

Taxonomic Publication and Size

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.

Dorsal Coloration and Patterning

Its coloration and patterning are highly variable: the base color is yellowish, brownish, or olive, overlaid with black and brown markings.

Hind Leg Underside Coloration

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.

Thigh and Throat Coloration

The throat ranges in color from white to yellow, and the thighs may be light orange or yellow.

Dorsal Spot Pattern

Along with its overall variable coloration, the species has a dorsal pattern of dark spots that vary in both shape and size.

Etymology of Specific Epithet

The specific epithet muscosa comes from the Latin word meaning "mossy" or "full of moss", a reference to the species' coloration.

Defensive Odor

When handled, the frog releases a defensive odor that resembles garlic.

Habitat Preferences

This frog inhabits mountain creeks, lakes, lakeshores, streams, and pools, and prefers sunny areas.

Aquatic Association and Respiration

It rarely travels far from water, and can stay underwater for very long periods of time, likely through cutaneous gas exchange.

Adult Microhabitat

Adults are often found on rocks near shorelines.

Oviposition Site Requirements

Close proximity to water is critical because the species lays its eggs either underwater attached to rocks or in shallow water.

Tadpole Habitat Needs

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.

Elevation Range

Rana muscosa has been recorded at elevations between approximately 1,214 and 7,546 feet (370 and 2,300 m) in California.

Geographic Distribution

Its suitable habitats are primarily located north of California in the Sierra Nevada, and south of California in the Transverse Ranges.

Post-Winter Emergence

The frog emerges from its wintering site shortly after snowmelt.

Breeding Season Timing

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.

Breeding Maturity Timeline

The time to reach breeding maturity varies from 1 to 4 years, depending on snow levels and temperature.

Larval Temperature Vulnerability

Very cold temperatures can cause larval death.

Fertilization and Egg Placement

Fertilization is external, and egg clusters are secured to vegetation in flowing water, or left floating freely in still water.

Tadpole Development Period

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.

Tadpole Age Classes and Metamorphosis Timing

Tadpoles are grouped into two classes: first-year tadpoles and second-year tadpoles, and metamorphosis usually occurs during the tadpole's second summer.

Metamorph and Juvenile Classification

Individuals undergoing the transition from tadpole to young frog are called metamorphs, and are classified as juveniles once they survive their first winter.

Reproductive Maturity Age

The frog becomes reproductively mature after 2 years in the juvenile stage.

Elevation Impact on Development

Overall, growth and development rates are slower at higher elevations.