California giant salamander

{{Speciesbox

| name = California giant salamander

| image = Dicamptodon ensatus01.jpg

| status = NT

| status_system = IUCN3.1

| status_ref = {{cite iucn |author=Hammerson, Geoffrey; Bury, Bruce |date=2004 |title=Dicamptodon ensatus |volume=2004 |page=e.T59080A11866765 |doi=10.2305/IUCN.UK.2004.RLTS.T59080A11866765.en |access-date=14 November 2021}}

| genus = Dicamptodon

| species = ensatus

| authority = (Eschscholtz, 1833)

| synonyms = *Triton ensatus
{{small|Eschscholtz, 1833}}

| synonyms_ref =

}}

The California giant salamander (Dicamptodon ensatus) is a species of salamander in the family Ambystomatidae. Dicamptodon ensatus is endemic to California, in the western United States. The species once additionally included individuals now belonging to the species D. aterrimus (Idaho giant salamander) and D. tenebrosus (coastal giant salamander), under the common name Pacific giant salamander, which now refers to the genus and family.

Taxonomy

The Pacific giant salamander (D. ensatus) was thought to consist of three geographic populations: an Idaho group, a group in northern California, and a group in Oregon and Washington.{{cite journal|title=Geographic variation and systematics of salamanders of the genus Dicamptodon Strauch (Ambystomatidae)|author=Nussbaum, Ronald A.|authorlink=Ronald Archie Nussbaum|journal=Miscellaneous Publications Museum of Zoology, University of Michigan|issue=149|pages=1–94|date=1976-04-23|url=http://deepblue.lib.umich.edu/bitstream/2027.42/56393/1/MP149.pdf|accessdate=2011-09-29}} In 1989 genetic studies showed that the D. ensatus populations consisted of three species: the Idaho giant salamander (Dicamptodon aterrimus) in Idaho, and two highly divergent species with a narrow hybrid zone in California, the coastal giant salamander (Dicamptodon tenebrosus) (ranging from northern California to Washington) and the California giant salamander (Dicamptodon ensatus) (ranging from Santa Cruz County to Mendocino County).{{cite journal|title=Hybridization and Cryptic Species in Dicamptodon (Caudata: Dicamptodontidae)|author=Good, David A.|author-link=species:David A. Good|journal=Evolution|date=July 1989|pages=728–744|jstor=2409302|volume=43|issue=4|doi=10.2307/2409302|pmid=28564189}}{{Cite web |title=California Giant Salamander - Dicamptodon ensatus |url=https://www.californiaherps.com/salamanders/pages/d.ensatus.html |access-date=2023-04-14 |website=www.californiaherps.com}} A fourth species of Dicamptodon, Cope's giant salamander (D. copei), lives on the Olympic Peninsula, Washington.

Habitat

The natural habitats of D. ensatus are damp temperate forests and clear, cold freshwater streams, ponds, and lakes.

File:Dicamptodon ensatus terrestrial adult.jpg

Studies have found the California giant salamander to be a good indicator species for the health of headwater streams.Fong, Darren, and Howell, J.A., 2006, Distribution and abundance of California giant salamander (Dicamptodon ensatus) and signal crayfish (Pacifastacus leniusculus) in the Upper Redwood Creek Watershed, Marin County, California: U.S. Geological Survey Open-File Report 2006–1066, 49 p.

Description

The adult California giant salamander can reach 17–30.5 cm (6.7–12 inches) in total length (including tail). Like most salamanders, the California giant salamander has four toes on the front feet and five toes on the back feet. The California giant salamander's tail is approximately 40% of the total length of the salamander and is laterally compressed. The head, back, and sides of the salamander have a marbled or reticulate pattern of dark blotches on a light brown or brassy-colored background. They have a broad head with a shovel-like snout and a fold of skin across the throat called the gular fold. The eyes are medium in size and have a brass-flecked iris and a large black pupil. This species is one of the few salamanders capable of vocalizing.{{cite web

|url=http://globaltwitcher.auderis.se/artspec_information.asp?thingid=42744

|title=California Giant Salamander: Dicamptodon ensatus

|author=Hogan, C. Michael

|year=2008

|editor=Nicklas Stromberg

|url-status=dead

|archiveurl=https://web.archive.org/web/20090130123737/http://globaltwitcher.auderis.se/artspec_information.asp?thingid=42744

|archivedate=2009-01-30

}}

Terrestrial adults search for prey such as snails, slugs, insects (such as beetles, caddisfly larvae, moths, and flies), other invertebrates, small mice (such as white-footed mice), shrews, possibly reptiles, and other amphibians (including reports of smaller D. ensatus) under surface objects and in tunnels.{{cite web | url=https://amphibiaweb.org/species/3866 | title=AmphibiaWeb - Dicamptodon ensatus }} Aquatic adults and larvae eat aquatic invertebrates, fish, snakes, and other amphibians.{{Cite web |last=Gonder |first=Michelle |title=Dicamptodon ensatus (California Giant Salamander) |url=https://animaldiversity.org/accounts/Dicamptodon_ensatus/ |access-date=2023-04-14 |website=Animal Diversity Web |language=en}} California giant salamanders are preyed upon by the American water shrew (Sorex palustris) and the western aquatic garter snake (Thamnophis couchi).

Disease has been known to lead to significant mortalities of California giant salamanders. In 2021, California Department of Fish and Wildlife observed poor body conditions and skin lesions on individuals at multiple sites. It was found to be the result of parasitic infections.Miller, Jaimie L., et al. "Morbidity in California Giant Salamander (Dicamptodon Ensatus Eschscholtz, 1833) Caused by Euryhelmis Sp. Poche, 1926 (Trematoda: Heterophyiidae)." International Journal for Parasitology: Parasites and Wildlife 23 (2024): 100908. Web.

Reproduction and development

The California giant salamander breeds from March to May, with egg-laying peaking in May. Eggs are concealed several feet below the surface in cold, slowly flowing water often beneath rocks and coarse woody debris in stream bottoms. Adults sometimes stay near their nests. Larvae may lose their external gills and transform to terrestrial adults after 1 to 2 years. In permanently perennial streams, adults may retain their gills and become aquatic adults. (See Neotenes below.)

Geographic range

The California giant salamander is endemic to Northern California and lives up to {{convert|6500|ft|m}} primarily in damp, coastal forests including coast Douglas fir (Pseudotsuga menziesii var. menziesii) and California coast redwood (Sequoia sempervirens) in both montane and valley-foothill riparian habitats. They tend to be common where they occur. The adult terrestrial form is found under surface litter and in tunnels, while the adult aquatic and larval forms are found mainly in cool, rocky streams and occasionally in lakes and ponds.{{cite report|title=California Giant Salamander|author=Kucera, Thomas|year=1997|publisher=California Department of Fish and Game|url=http://nrm.dfg.ca.gov/FileHandler.ashx?DocumentVersionID=17590|accessdate=2011-09-29}}

It is found in two (possibly three) isolated regions. The first range includes Sonoma, Napa, and Marin Counties, southwestern Lake County, western Glenn County, and southern Mendocino County. The other documented region is south of the San Francisco Bay from central San Mateo County to southern Santa Cruz County plus western Santa Clara County. The California giant salamander does not occur in the East Bay, forming a gap between these two populations.{{Cite web |title=IUCN Red List maps |url=http://maps.iucnredlist.org/map.html?id=59080 |access-date=2023-04-14 |website=Explore and discover Red List species ranges and observations}} There is an unconfirmed sight record from Big Sur in Monterey County, approximately 75 miles (100 km) to the south of the documented population in the Santa Cruz area.

Neotenes

Some California giant salamander larvae continue to grow into adults and become sexually mature without losing their external gills. This process is called neoteny. Adult-sized neotenes have a uniform brown coloring on their heads, sides, and backs and retained external gills which allow them to live in perennial streams as aquatic adults.