Description
Ambystoma leorae, or the Leora’s Stream Salamander has an average snout-vent-length of 76.5 mm (Lemos-Espinal et al. 2017). It has a rounded head characteristic of Ambystoma genus. Additionally, it has four robust limbs, with four fingers on forelimbs and five toes on hind limbs. Adults commonly retain neotenous features such as external gills (Monroy-Vilchis et al. 2015).

Diagnosis:

Ambystoma leorae has a smaller snout-vent length than other Ambystoma mole salamanders, including Ambystoma mexicanum and Ambystoma lermaense, which also reside in Mexico (Sunny et al. 2014).

Coloration:

Ambystoma leorae is dark brown or black, with lighter yellow or brown mottling across its back and tail. Individuals all have mottling, but exact coloration varies between darker and lighter shades (Shaffer et al. 2008). They are not sexually dimorphic in coloration (Lemos-Espinal et al. 2017).

Variation:

Individually, there is mild variation in coloration with slightly lighter and darker shades of A. leorae (Shaffer et al. 2008). Males tend to have swelling in the cloacal region on both sides of the tail while females do not (Lemos-Espinal et al. 2017).

Distribution and Habitat

Country distribution from AmphibiaWeb's database: Mexico

View distribution map in BerkeleyMapper.

Ambystoma leorae can be found near the town of Río Frío, in Iztaccihuatl-Popocatepetl National Park, Mexico. The species is considered a microendemic because it is believed to only be restricted to six small locations within this region and nowhere else in the world (Sunny et al. 2014).

It prefers cold freshwater streams, pools, and slow-moving streams with high oxygen content in humid, high-altitude pine forests at elevations of about 3,000 meters above sea level (Shaffer et al. 2008, Sunny et al. 2014). There is a wide variety of vegetation in the region, including pines, firs, oaks, Mexican Alders, Mexican Strawberry Trees, Manzanitas, Mexican Lupine, Pineapple Sage, Mühlenberg Grass, Old-man Bush, Toluca Bentgrass, and Fescue Grass (Lemos-Espinal et al. 2017).

Life History, Abundance, Activity, and Special Behaviors
This species is highly aquatic across all life stages. Its eggs and larvae develop in the water, and the adults do not stray far from their natal streams (Reilly and Brandon 1994).

Adults exhibit neoteny; they retain some juvenile features such as filamentous external gills. In addition, Ambystoma retain longitudinal rows of teeth as they develop from larvae to adults. This partial paedomorphosis allows adults to take advantage of the same aquatic food sources as their larvae (Reilly and Brandon 1994).

The temperature of the water in which it lives ranges between 6 - 15^°C (Monroy-Vilchis et al. 2015). Adults can be found in sites with mud, sand, or mud/gravel. Some streams have a “sinuous” condition because of erosion along the banks of the stream. Crevices formed by this erosion have been noted as a common place for the salamander to lay its egg masses (Lemos-Espinal et al. 2017).

In comparison to most salamanders (including other Ambystoma), A. leorae produces a relatively low number of eggs. The egg masses range from about 6 - 9 eggs. The low number of eggs is compensated by the fact that they lay larger eggs than other mole salamanders (Sunny et al. 2014). Eggs are laid in muddy bottom streams, attached to vegetation. They have been observed laying eggs on vegetation within crevices along the banks of the streams. Observations suggest that egg-laying occurs from April to June. This is similar to other populations of Mexican Ambystoma, as this particular month range correlates with the rainy season in central Mexico (Lemos-Espinal et al. 2017).

Their diet consists of aquatic insects (Lemos-Espinal et al. 2017).

Ambystoma mexicanum are found nearby and occupy a similar niche. Extrapolating from A. mexicanum, it is likely that A. leorae has few natural predators. However, A. mexicanum is experiencing population declines due to the introduction of the two exotic fish: carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) (Zambrano et al. 2010). These fish do not prey on the adult salamanders directly but compete with salamanders for food and eat their eggs.

Larva
The larvae have gills and a snout-vent-length between 19 - 103 mm (Monroy-Vilchis et al. 2015).

This species is highly aquatic across all life stages. Its eggs and larvae develop in the water, and the adults do not stray far from their natal streams (Reilly and Brandon 1994). Larvae are usually only found in sites with mud bottoms and submerged aquatic vegetation/algae (Lemos-Espinal et al. 2017).

Trends and Threats
Ambystoma leorae has an IUCN Red List of Threatened Species status of “Critically Endangered” (Shaffer 2008). Additionally, it is considered a threatened species by the Mexican Government (SEMARNAT 2010). This species, once common, has undergone steady decline (Shaffer et al. 2008) to the point that several researchers thought it had gone extinct. However in the 1990s and 2010s, relic populations were identified (Sunny et al. 2013). In 2011, 161 individual specimens were documented in Iztaccihuatl-Popocatepetl National Park - the highest count of the species ever recorded (Sunny et al. 2014). Their populations declined due to various sources of habitat degradation including stream pollution logging of pine forests, predation from invasive fish species, livestock farming/ranching, and development of urban, residential, tourist, and recreational areas have all contributed to the decline of this species, with invasive fish as a more minor threat (Shaffer et al. 2008, Lemos-Espinal et al. 2017).

If the amphibian pathogen, Batrachochytrium salamandrivorans, were to be introduced to the Western Hemisphere, it could have drastic impacts on A. leorae (IUCN 2020).

Relation to Humans
Historically, humans used this species as a food source. However, with the species’ decline, this practice has been mostly discontinued. As a former delicacy, A. leorae is a culturally significant species to local peoples in the area (Shaffer et al. 2008, IUCN 2020).

Possible reasons for amphibian decline

General habitat alteration and loss
Habitat modification from deforestation, or logging related activities
Intensified agriculture or grazing
Urbanization
Predators (natural or introduced)
Introduced competitors

Comments
Ambystoma leorae has relatively high levels of genetic diversity for its limited population/range. However, it still shows signs of having undergone a genetic bottleneck (Sunny et al. 2013).

The species epithet, "leorae," is in honor of Leora T. Forbes, who was the wife of the collector of the type specimens (Tighe 2023).

References

IUCN SSC Amphibian Specialist Group. (2020). "Ambystoma leorae." The IUCN Red List of Threatened Species 2020: e.T59061A53974072. https://dx.doi.org/10.2305/IUCN.UK.2020-2.RLTS.T59061A53974072.en. Accessed on 19 October 2022.

Lemos-Espinal, J. A., Smith, G. R., Estrella Zamora, A. B., Woolrich-Piña, G., Montoya Ayala, R. (2017). “Natural history of the critically endangered salamander Ambystoma leorae (Caudata:Ambystomatidae) from the Río Tonatzin, Mexico.” Phyllomedusa 16,1: 3-11 [link]

Monroy-Vilchis, O., Zarco-González M. M., Domínguez-Vega, H., Sunny, A. (2015). “Ambystoma leorae (Taylor, 1943). New records, natural history notes and threat status.” Herpetozoa 27(3/4),166-168 [link]

Reilly, S. M., Brandon, R. A. (1994). “Partial paedomorphosis in the Mexican stream ambystomatids and the taxonomic status of the genus Rhyacosdiredon Dunn.” Copeia 1994(3),656-662 [link]

SEMARNAT (Secretara de Medio Ambiente y Recursos Naturales). (2010). Norma Oficial Mexicana NOM-059 Ecol-2010. Protección ambiental-Especies nativas de México de flora y fauna silvestres- Categorías de reisgo y especifaciones para su inclusion, exclusion o cambio- Lista de especies en riesgo. Diario oficial (Segunda Seccion, 30-dic).

Shaffer, H.B., Parra-Olea, G., Wake, D. (2008). "Ambystoma leorae." The IUCN Red List of Threatened Species 2008: e.T59061A11877775. http://dx.doi.org/10.2305/IUCN.UK.2008.RLTS.T59061A11877775.en. Downloaded on 15 February 2018.

Sunny, A., Monroy-Vilchis, O., Fajardo, V., Aguilera-Reyes, U. (2013). “Genetic diversity and structure of an endemic and critically endangered stream river salamander (Caudata: Ambystoma leorae) in Mexico.” Conservation Genetics 15(1), 49-59. [link]

Sunny, A., Monroy-Vilchis, O., Reyna-Valencia, C., Zarco-Gonzalez, M. (2014). “Microhabitat types promote the genetic structure of a micro-endemic and critically endangered mole salamander (Ambystoma leorae) of Central Mexico.” PLoS One 9(7), e103595 [link]

Tighe, K.A. (2023). Catalog of type specimens of recent Caudata and Gymnophiona in the National Museum of Natural History, Smithsonian Institution. Smithsonian Contributions to Zoology 654.

Zambrano, L., Valiente, E., Vander Zanden, M.J., (2010). “Food web overlap among native axolotl (Ambystoma mexicanum) and two exotic fishes: carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) in Xochimilco, Mexico City.” Biological Invasions 12(9), 3061-3069 [link]

Species Account Citation: AmphibiaWeb 2023 Ambystoma leorae: Leora’s Stream Salamander <https://amphibiaweb.org/species/3837> University of California, Berkeley, CA, USA. Accessed Nov 21, 2024.

Citation: AmphibiaWeb. 2024. <https://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Nov 2024.

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