Blunt-headed salamander

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Blunt-headed salamander
Blunt-headed Salamander imported from iNaturalist photo 348717823 on 16 February 2024.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Amphibia
Order: Urodela
Family: Ambystomatidae
Genus: Ambystoma
Species:
A. amblycephalum
Binomial name
Ambystoma amblycephalum
Taylor, 1940

The blunt-headed salamander (Ambystoma amblycephalum) is a mole salamander endemic to Mexico. It is only known from the vicinity of its type locality, near Morelia, in Michoacán state in Southwestern Mexico. [2] It inhabits a landscape consisting of a mosaic of natural grasslands and pine-oak forests at elevations of about 2,000 m (6,600 ft) asl. Breeding takes place in ponds. [1] An average adult has a mass of 6.18 grams while wet. [3] Adult females of the species range from 42-93 mm and males range from 45.4-70.5 mm in standard length. [4]

It has both neotenic and terrestrial populations. Neotenic populations are perennibranchiate and retain their fins. Neotenes are very long with extremely short, blunt heads and round eyes. They have relatively short, thick gills. Their coloring is dark brown-gray dorsally, with a lighter gray under-belly. They have small, dark marks on their head and back. [5]

Habitat

Blunt-headed salamanders are native only to a small region of Michoacán located in Mexico. They inhabit pine forests in hilly regions located near agricultural sites. These areas are typically subjected to fragmentation. [4] They also are found in grasslands, and mostly exist on land. They need wetland areas with ponds for breeding. Some have been found to utilize cattle ponds with muddy bottoms during larval stages. [1] Blunt-headed salamanders have been discovered hiding under logs nearby to ponds and wetland breeding sites. Their region has humid weather during all seasons, with the rainy season occurring in the summer. The area contains an arrangement of native grass and shrub species. [4]

Lifecycle

The blunt-headed salamander requires aquatic environments for breeding. Egg masses are laid attached to roots or other vegetation nearby to ponds such as algae. These masses contain between 170 and 220 individual eggs. Most eggs had a transparent layer of gelatinous material, a few eggs were found to be opaque. The diameter of each egg ranged from 4.5-5.5 mm (0.177-0.217 inches). [5]

Larva

The larva or tadpole stage of the blunt-headed salamander involves development in an aquatic environment. The larvae of this species range from 60-77 mm (2.36-3.03 inches) in standard length. The larvae possess gills with red coloration, as well as a large dorsal fin. [4] It was found that certain aquatic insects and their larval forms may be a part of the diet of the blunt-headed salamander larvae. These include water fleas such as Daphnia and aquatic beetles such as Belostomatidae and Platambus mexicanus. [5]

Adult

Some adults of this species are known to retain larval traits, also known as neoteny. The neotenic adults retain their gills and fins, and continue to require aquatic environments throughout their adult lives. Other adults of the species are terrestrial, living in grasslands and pine-forests. They spend a majority of the year in underground burrows, and will emerge during mating season to migrate to the water.

Morphology

Females range from 42-93 mm (1.65-3.66 inches) in standard length. Including the tail, females can have total lengths up to 161 mm (6.34 inches). Males of this species are typically smaller than females. Their standard lengths range from 45.4-70.5 mm (1.79-2.78 inches). Their total length has been recorded up to 128.8 mm (5.07 inches). [4] Their tails are similar in length to their bodies. They have 70-80 maxillary-premaxillary teeth and 11 costal grooves. [5] Their limbs are long and webbing of the feet is found in adults.

Coloration differs based on the lifecycle stage of the salamanders. Some individuals ranged from black to an olive-green dorsally, and ventrally are grey with some creme-colored spots. These spots are primarily observed in adult males. Few individuals have been found to possess redness on their gills. This was noted in younger individuals, with the older ones being faded. [5]

Conservation concerns

The blunt-headed salamander is currently listed as critically endangered by the IUCN. The Mexican government officially protects the blunt-headed salamander and the species maintains a special protection status in the country. [5] Along with many other species of amphibians, they are at risk of habitat loss, habitat fragmentation, pollution, and predation. The habitat risks are mainly due to new development and logging practices. The primary threat of this species is the loss of ponds necessary for breeding due to agricultural expansion. [1] Along with agricultural expansion, they also face the risk of pesticides impacting water quality. There is also risk of poaching by local individuals. It is believed that some individuals consume these salamanders.

Related Research Articles

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Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All ten extant salamander families are grouped together under the order Urodela from the group Caudata. Salamander diversity is highest in eastern North America, especially in the Appalachian Mountains; most species are found in the Holarctic realm, with some species present in the Neotropical realm.

<span class="mw-page-title-main">Mole salamander</span> Genus of amphibians

The mole salamanders are a group of advanced salamanders endemic to North America. The group has become famous due to the presence of the axolotl, widely used in research due to its paedomorphosis, and the tiger salamander which is the official amphibian of many US states, and often sold as a pet.

<span class="mw-page-title-main">Tiger salamander</span> Species of amphibian

The tiger salamander is a species of mole salamander and one of the largest terrestrial salamanders in North America.

<span class="mw-page-title-main">California tiger salamander</span> Species of amphibian

The California tiger salamander is a vulnerable amphibian native to California. It is a mole salamander. Previously considered to be a subspecies of the tiger salamander, the California tiger salamander was recently designated a separate species again. The California tiger salamander distinct population segment (DPS) in Sonoma County and the Santa Barbara County DPS are listed as federally endangered, while the Central California DPS is listed as federally threatened. The Sonoma County, south San Joaquin, and the Santa Barbara County DPS have diverged from the rest of the California tiger salamander populations for over one million years, since the Pleistocene and they may warrant status as separate species.

<span class="mw-page-title-main">Jefferson salamander</span> Species of amphibian

The Jefferson salamander is a mole salamander native to the northeastern United States, southern and central Ontario, and southwestern Quebec. It was named after Jefferson College in Pennsylvania.

<span class="mw-page-title-main">Ringed salamander</span> Species of amphibian

The ringed salamander is a species of mole salamander native to hardwood and mixed hardwood-pine forested areas in and around the Ozark Plateau and Ouachita Mountains of Arkansas, Oklahoma, and Missouri. This species of salamander has slander body, small head, and long tail. They are usually found to have various dorsal color from dark gray to dark brown. Various close relatives are found such as marbled salamander and spotted salamander. This species of salamander has cannibal behavior especially those in large body size.

<span class="mw-page-title-main">Frosted flatwoods salamander</span> Species of amphibian

The frosted flatwoods salamander is an endangered salamander species native to the Southeastern United States.

<span class="mw-page-title-main">Northwestern salamander</span> Species of amphibian

The northwestern salamander is a species of mole salamander that inhabits the northwest Pacific coast of North America. These fairly large salamanders grow to 8.7 in (220 mm) in length. It is found from southeastern Alaska on May Island, through Washington and Oregon south to the mouth of the Gualala River, Sonoma County, California. It occurs from sea level to the timberline, but not east of the Cascade Divide. Its range includes Vancouver Island in British Columbia and The San Juan Islands, Cypress, Whidbey, Bainbridge, and Vashon Islands in Washington.

<span class="mw-page-title-main">Long-toed salamander</span> Species of amphibian

The long-toed salamander is a mole salamander in the family Ambystomatidae. This species, typically 4.1–8.9 cm (1.6–3.5 in) long when mature, is characterized by its mottled black, brown, and yellow pigmentation, and its long outer fourth toe on the hind limbs. Analysis of fossil records, genetics, and biogeography suggest A. macrodactylum and A. laterale are descended from a common ancestor that gained access to the western Cordillera with the loss of the mid-continental seaway toward the Paleocene.

<span class="mw-page-title-main">Taylor's salamander</span> Species of amphibian

Taylor's salamander is a species of salamander found only in Laguna Alchichica, a high-altitude crater lake to the southwest of Perote, Mexico. It was first described in 1982 but had been known to science prior to that. It is a neotenic salamander, breeding while still in the larval state and not undergoing metamorphosis. The lake in which it lives is becoming increasingly saline and less suitable for the salamander, which is declining in numbers. The International Union for Conservation of Nature (IUCN) has rated it as being "critically endangered".

<span class="mw-page-title-main">Anderson's salamander</span> Species of amphibian

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<span class="mw-page-title-main">Lake Patzcuaro salamander</span> Species of amphibian

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<span class="mw-page-title-main">Marbled salamander</span> Species of amphibian

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<span class="mw-page-title-main">Yellow-peppered salamander</span> Species of amphibian

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<span class="mw-page-title-main">Lesser siren</span> Species of amphibian

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<span class="mw-page-title-main">Barred tiger salamander</span> Species of amphibian

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<span class="mw-page-title-main">Tarahumara salamander</span> Species of amphibian

The Tarahumara salamander is a freshwater species of mole salamander in the family Ambystomatidae, endemic to Mexico. Its natural habitats are temperate forest, subtropical or tropical moist montane forest, subtropical or tropical high-altitude grassland, rivers, freshwater marshes, pastureland, and ponds.

References

  1. 1 2 3 4 IUCN SSC Amphibian Specialist Group (2016). "Ambystoma amblycephalum". IUCN Red List of Threatened Species . 2016: e.T59050A53973313. doi: 10.2305/IUCN.UK.2016-1.RLTS.T59050A53973313.en . Retrieved 12 November 2021.
  2. Frost, Darrel R. (2014). "Ambystoma amblycephalum Taylor, 1940". Amphibian Species of the World: an Online Reference. Version 6.0. American Museum of Natural History. Retrieved 8 March 2014.
  3. "Ambystoma amblycephalum Taylor 1940 - Encyclopedia of Life". eol.org. Retrieved 2024-04-27.
  4. 1 2 3 4 5 "AmphibiaWeb - Ambystoma amblycephalum". amphibiaweb.org. Retrieved 2024-04-27.
  5. 1 2 3 4 5 6 Hernandez, Axel; Dufresnes, Christophe; Raffaëlli, Jean; Jelsch, Emmanuel; Dubey, Sylvain; Santiago-Pérez, Ana Luisa; Rosas-Espinoza, Verónica Carolina; Nuñez, Pablo Berea (2022-12-31). "Hope in the dark: discovery of a population related to the presumably extinct micro-endemic Blunt-headed Salamander ( Ambystoma amblycephalum )". Neotropical Biodiversity. 8 (1): 35–44. doi:10.1080/23766808.2022.2029323. ISSN   2376-6808.