Ensatina

The ensatina (Ensatina eschscholtzii) is a species complex of plethodontid (lungless) salamanders^[2] found in coniferous forests, oak woodland and chaparral^[3] from British Columbia, through Washington, Oregon, across California (where all seven subspecies variations are located), all the way down to Baja California in Mexico. The genus Ensatina originated approximately 21.5 million years ago.^[4] It is usually considered as monospecific, being represented by a single species, Ensatina eschscholtzii, with several subspecies forming a ring species.

Ensatina
Monterey Ensatina (Ensatina eschscholtzii eschscholtzii)
Conservation status
Least Concern  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Amphibia
Order:	Urodela
Family:	Plethodontidae
Subfamily:	Plethodontinae
Genus:	Ensatina Gray, 1850
Species:	E. eschscholtzii
Binomial name
Ensatina eschscholtzii Gray, 1850
Synonyms
Ensatina klauberi Heredia oregonensis Plethodon croceater Urotropis platensis

Description

Ensatina eschscholtzii klauberi, the large-blotched ensatina

E. eschscholtzii eschscholtzi, the Monterey ensatina

The subspecies Ensatina e. eschscholtzii, the Monterey ensatina, can be found in Santa Cruz and Monterey Counties and into the California coastal mountains. With a head-to-tail length of just between 3–5 in (7.6–12.7 cm), E. e. eschecholtzi can be identified primarily by its tail, which is narrower at the base; it is the only subspecies that has such a tail structure, as well as five toes on the hind limbs.

Males often have longer tails than the females, and many of these salamanders have lighter-colored limbs, compared to the rest of the body. The adult females lay eggs underground, often in sets of threes, which hatch directly into fully-formed salamanders, skipping the usual aquatic juvenile phase.

The subspecies Ensatina eschscholtzii klauberi, or the large-blotched ensatina, can be found along the mountain ranges of Southern California, and south into a small region of the Sierra Juarez in northern Baja California.

E. e. klauberi is similar in size to E. e. eschscholtzii; it is mid-sized, with adults growIng a total length of 3–6 in (7.6–15.2 cm). Females tend to have shorter, wider bodies compared to the males. However, this subspecies differs from E. e. eschscholtzii in its coloration—nearly black, with blotches of orange, tail, and dark eyes.^[5]

As a ring species

Ensatina eschscholtzii has been described as a ring species in the mountains surrounding the Californian Central Valley.^[2] The complex population forms a horseshoe shape around the mountains, and although interbreeding can happen between each of the 19 populations around said horseshoe, the Ensatina eschscholtzii subspecies on the western end of the horseshoe cannot interbreed with the Ensatina klauberi on the eastern end.^[6] As such, it is thought to be an example of incipient speciation, providing an illustration of "nearly all stages in a speciation process" (Dobzhansky, 1958).^[2][7] Richard Highton, zoologist, argued that Ensatina is a genus of multiple species and not a continuum of one (meaning, by traditional definitions, it is not a ring species).^[8]

Distribution and habitat

They are generally thought to be found in high elevations, from 520 to 2400m, in conifer forests and oak woodlands. However, populations were discovered along the coast in Volcán Riveroll, a volcanic area located in Baja California. It is thought that they are able to survive in this anomalous region due to the high moisture that comes in from the coast. It is unclear how these populations were able to end up in this coastal region, but it is hypothesized that “the subspecies was once more broadly distributed and became isolated as a result of climate change during the late Pleistocene and Holocene.” ^[9] If this is true, then it is estimated that Ensatina klauberi has been living in this region for thousands of years.

Relationships with humans

Ensatina can usually be found under logs or brush, by or in streams and lakes, and in other moist places. They are easily distressed by improper handling, because they rely on cutaneous respiration, their thin skin is very sensitive to heating, drying and exposure to chemicals from warm hands. They may exude a sticky milky secretion from the tail.^[10]

Subspecies

E. e. platensis from Fresno County, California

• Yellow-blotched ensatina — E. e. croceater (Cope, 1868)
• Monterey ensatina — E. e. eschscholtzii Gray, 1850
• Large-blotched ensatina — E. e. klauberi Dunn, 1929
• Oregon ensatina — E. e. oregonensis (Girard, 1856)
• Painted ensatina — E. e. picta Wood, 1940
• Sierra Nevada ensatina — E. e. platensis (Jiménez de la Espada, 1875)
• Yellow-eyed ensatina — E. e. xanthoptica Stebbins, 1949