Natural history of the critically endangered salamander Ambystoma leorae (Caudata: Ambystomatidae) from the Río Tonatzin, Mexico

Abstract

Natural history of the critically endangered salamander Ambystoma leorae (Caudata: Ambystomatidae) from the Río Tonatzin, Mexico. In Mexico, many species of Ambystoma are endangered, but unfortunately little is known about their natural history and ecology. We report on aspects of the natural history of A. leorae, a critically endangered endemic salamander, from the Río Tonatzin, State of México, Mexico. We observed egg masses, which were attached to vegetation, from April to June, with a mean of 7.28 eggs per egg mass. Larval A. leorae were found in sections of the Río Tonatzin with muddy bottoms and submerged aquatic vegetation. We observed adult and juvenile salamanders throughout the year except September, but with a peak from May to July. The use of sites along the Río Tonatzin by adult and juvenile A. leorae was driven primarily by vegetation type and substrate type of the site, with mud or sand substrate with grass roots and submerged aquatic vegetation being the most used site types. We found no evidence of sexual dimorphism in A. leorae. Our results suggest that adult and juvenile A. leorae use a variety of stream sites, although larvae appear to be more limited in their use of stream sites. These observations indicate that to maintain this population of A. leorae, the general conditions existing in the Río Tonatzin should be protected, especially the sections with muddy bottoms and aquatic vegetation where larvae, juveniles, and adults are found.

Metamorphosis and seasonality are major determinants of chytrid infection in a paedomorphic salamander

“…Some Ambystoma species are considered obligate paedomorphs which never go through metamorphosis, and others are considered facultative paedomorphs which can metamorphose under certain conditions to transform from aquatic larvae to terrestrial adults (Everson et al ., 2021). Ambystoma altamirani is a facultative paedomorphic salamander with a distribution restricted to the high mountain streams of Central Mexico (Lemos‐Espinal et al ., 1999, 2016; Woolrich‐Piña et al ., 2017; IUCN, 2020). This species is considered threatened by Mexican law (NOM‐059, SEMARNAT, 2015) and Endangered by the IUCN (IUCN, 2020).…”

“…This species is considered threatened by Mexican law (NOM‐059, SEMARNAT, 2015) and Endangered by the IUCN (IUCN, 2020). Populations of A. altamirani are subject to many threats such as urbanization, pollution, land‐use change, the introduction of invasive fish, and diseases (Lemos‐Espinal et al ., 1999, 2016; Frías‐Alvarez et al ., 2008; Basanta et al ., 2021). Because gilled and non‐gilled individuals stay in or near aquatic habitats throughout their entire life (Lemos‐Espinal et al ., 1999; Camacho et al ., 2020), the presence of aquatic pathogens such as B. dendrobatidis may pose a substantial risk to populations' health, and may differentially affect gilled and non‐gilled individuals.…”

Análisis de la categoría de riesgo de los ajolotes de arroyos de alta montaña (Caudata: Ambystoma)

“…Ocupa un área de distribución aproximada de 985,900 km 2 . En ambos estados se reportaron bajas densidades poblacionales entre los años 1985 y 1999, de entre cuatro y 59 individuos; actualmente la población, que parece ser la más estable y abundante, se encuentra en el Monte Tláloc dentro del Parque Nacional Iztaccíhuatl-Popocatépetl (PNIP), donde se han reportado hasta 223 individuos (Sunny et al, 2014b;Monroy-Vilchis et al, 2015;Lemos-Espinal et al, 2017).…”

The relationship between body and substrate color for Ambystoma altamirani (Caudata: Ambystomatidae) from the Arroyo los Axolotes, Mexico

“…For example, larval A. texanum select the substrate that is most similar to their body color . Substrate color is a significant factor in determining the presence or absence of A. leorae (Taylor, 1943) in sites along the Río Tonatzin in the state of México (Lemos-Espinal et al 2017), and a previous study found that Ambystoma altamirani Dugès, 1895 in the Arroyo los Axolotes used black substrates more than expected and white-yellow sites less than expected (Lemos-Espinal et al 2016).…”