Description
A stocky, medium to large salamander. Terrestrial adults have a brownish black dorsum and bright red venter. The skin is grainy in appearance. Aquatic males (breeding season only) have a brownish dorsum with bright red venter, and a broad, dark stripe across vent. The skin is smooth or slimy (Stebbins 1972; Petranka 1998). Snout to vent length of adults 5.9 to 8.1 cm (14-19.5 cm total length. Larvae are pond-type with incompletely developed or non-existent balancers and even, dark pigmentation on the sides and dorsum. A moderately high tail fin extends forward but does not reach the shoulders (Stebbins 1985; Petranka 1998).

Taricha rivularis may be distinguished from close relatives (T. granulosa and T. torosa) by relatively prominent eyes, brown iris, and bright red ventral coloration with a dark bar across its vent (Stebbins 1951; Petranka 1998).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: United States

U.S. state distribution from AmphibiaWeb's database: California

	View distribution map in BerkeleyMapper.
	View Bd and Bsal data (203 records).

The range of Red-bellied newts covers northwestern California, including Sonoma, Mendocino, and Humboldt Counties. The habitat is characterized by coastal redwood forests and cold, rocky, forest streams with moderate to fast current (Petranka 1998; Stebbins 1972).

In 2014, several individuals were discovered in Santa Clara County, significantly south (ca. 130 km) from its previously known range (Reilly et al. 2014). These adults were seen with egg masses so recruitment is likely. Reilly et al (2014) tried to determine the origin of this disjunct population by comparing a few molecular markers with populations from the north of San Francisco Bay. However due to the extremely low genetic diversity across its range it was inconclusive whether the population in Santa Clara County represents a previously unknown but natural range extension or an introduced population.

Life History, Abundance, Activity, and Special Behaviors
Adults appear above ground after the first few rains during the autumn months and begin to orient towards breeding sites in late January, with peak migration in early March. Movements are concentrated in the five hours following sunset on warmer, humid nights with moderate or no rain. Breeding occurs in fast-moving streams, and does not take place in standing water like related species of Taricha. Animals show philopatry and return to the same (or nearby) sites to breed each year. Courtship includes a period of amplexus where the male grasps the female and rubs her head with his. Eventually, the male deposits a spermatophore on the substrate and the female picks this up in her cloaca. Females deposit eggs in small, flattened masses, usually one layer thick. Masses contain 5-15 eggs, average 9. Egg deposition sites are in fast-flowing water on the undersides of stones or attached to rootlets. Eggs hatch after 20-30 days and larvae metamorphose after four months (by August). The juvenile stage lasts 5 years, during which time the animal is rarely seen above ground. Individual red-bellied newts may live as long as 15 years. See Petranka (1998) for references.

Diet is likely composed of terrestrial and aquatic invertebrates although this has been poorly studied (Petranka 1998). When attacked, T. rivularis assumes the characteristic "unken reflex" of all species of Taricha: the tail and head are raised to expose the bright red belly as a warning to predators (Brodie 1977). All Taricha produce the neurotoxin known as tetrodotoxin, which is toxic to their predators and humans (Brodie et al. 1974; Petranka 1998).

Trends and Threats
Taricha rivularis can be considered common. However, long-term population studies are lacking for this species (Petranka 1998).

Based on low genetic diversity, limited geographic range and potential habitat, and high potential for habitat disturbance, Reilly et al (2014) recommends conservation protection for this species.

Possible reasons for amphibian decline

Loss of genetic diversity from small population phenomena

Comments

See another account at californiaherps.com.

This species was featured as News of the Week on 2 August 2021:

Most amphibians secrete distasteful or toxic substances from their skin. Several groups wield toxins that can be lethal to other animals, or even to themselves. Animals can evolve resistance to toxins through mutations in proteins that prevent toxins from binding. Although these mutations can provide resistance, they often occur in important regions of a protein, such as those critical to nervous system functions. Thus, a problem arises: how can animals avoid the negative effects of mutations that also provide resistance? A pair of recent studies, one on the toxic salamanders Taricha (Gendreau et al. 2021) and another on frogs of the genus Leptodactylus (Mohammadi et al. 2021), which consume toxic toads, suggest that gene duplication is the key; one gene copy can help animals develop toxin resistance while the other copy maintains a functional nervous system. Both studies also show evidence for a fascinating molecular process known as gene conversion, wherein duplicate copies of one gene retain more similar-than-expected DNA sequences. During homologous recombination, two copies of a genome line up and exchange pieces of DNA; however, when two copies of a gene are near each other in the genome, the wrong genes can line up and exchange genetic material, maintaining genetic similarity between duplicate copies of a gene. In newts, gene conversion appears to have copied resistance-conferring mutations from one gene domain to another. In Leptodactylus frogs, strong natural selection countered the force of gene conversion, resulting in one toxin-resistant gene and one toxin-sensitive gene. How newts and frogs regulate the use of these different gene copies remains unknown and will be an exciting future research topic. (RT)

References

Brodie, E. D., Jr. (1977). "Salamander antipredator postures." Copeia, 1977, 523-535.

Brodie, E. D., Jr., Hensel, J. L., and Johnson, J. A. (1974). ''Toxicity of the urodele amphibians Taricha, Notophthalmus, Cynops, and Paramesotriton (Family Salamandridae).'' Copeia, 1974(2), 506-511.

Petranka, J. W. (1998). Salamanders of the United States and Canada. Smithsonian Institution Press, Washington D.C. and London.

Reilly, S.B., Portik, D.M., Koo, M.S., and Wake, D.B. (2014). ''Discovery of a New, Disjunct Population of a Narrowly Distributed Salamander (Taricha rivularis) in California Presents Conservation Challenges.'' Journal of Herpetology, 48(3), 371-379 .

Stebbins, R. C. (1972). Amphibians and Reptiles of California. University of California Press, Berkeley, Los Angeles, London.

Stebbins, R. C. (1985). A Field Guide to Western Reptiles and Amphibians. Houghton Mifflin, Boston.

Stebbins, R.C. (1951). Amphibians of Western North America. University of California Press, Berkeley.

Twitty, V. C. (1964). ''Taricha rivularis (Twitty). Red-bellied Newt.'' Catalogue of American Amphibians and Reptiles. American Society of Ichthyologists and Herpetologists, 9.1-9.2.

Species Account Citation: AmphibiaWeb 2021 Taricha rivularis: Red-bellied Newt <https://amphibiaweb.org/species/4289> University of California, Berkeley, CA, USA. Accessed Jan 24, 2025.

Citation: AmphibiaWeb. 2025. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 24 Jan 2025.

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