In Search of Critically Endangered Species: The Current Situation of Two Tiny Salamander Species in the Neotropical Mountains of Mexico

Abstract

Worldwide, one in every three species of amphibian is endangered, 39 species have gone extinct in the last 500 years and another 130 species are suspected to have gone extinct in recent decades. Of the amphibians, salamanders have the highest portion of their species in one of the risk categories, even higher than the frogs. To date there have been few studies that have used recent field data to examine the status of populations of endangered salamanders. In this study we evaluate the current situation of two tiny salamanders, Parvimolge townsendi and Thorius pennatulus, both of which are distributed at intermediate elevations in the mountains of the northern Neotropics and are considered to be critically endangered; the first has been proposed as possibly extinct. By carrying out exhaustive surveys in both historical and potentially suitable sites for these two species, we evaluated their abundance and the characteristics of their habitats, and we estimated their potential geographic distribution. We visited 22 sites, investing 672 person-hours of sampling effort in the surveys, and found 201 P. townsendi salamanders in 11 sites and only 13 T. pennatulus salamanders in 5 sites. Both species were preferentially found in cloud forest fragments that were well conserved or only moderately transformed, and some of the salamanders were found in shade coffee plantations. The potential distribution area of both species is markedly fragmented and we estimate that it has decreased by more than 48%. The results of this study highlight the importance of carrying out exhaustive, systematic field surveys to obtain accurate information about the current situation of critically endangered species, and help us better understand the crisis that amphibians are facing worldwide.

Amphibian Diversity and Threatened Species in a Severely Transformed Neotropical Region in Mexico

“…However, more data are needed based on field surveys (i.e. surveying canopy microhabitats, extending sampling effort to the dry season) to be able to provide a reliable assessment of their level of risk (see Sandoval-Comte et al [ 29 ]).…”

Spatial and temporal variation in amphibian metacommunity structure in Chiapas, Mexico

“…Our results point to the former for these amphibian assemblages, while some studies elsewhere, for other types of system, have shown the latter to apply (Keith et al 2011). It has long been known that sampling size affects the outcomes of biodiversity studies (Preston 1960), species-specific sampling (Sandoval-Comte et al 2012) and of community analyses (Lande et al 2003). Although we compared the same number of sites, the distribution of individuals varied between the two years, seemingly reflecting environmental variation driving the community dynamics (Grøtan et al 2012, Guo et al 2002).…”

Microhabitat Types Promote the Genetic Structure of a Micro-Endemic and Critically Endangered Mole Salamander (Ambystoma leorae) of Central Mexico

“…Exact collection localities were determined using a global positioning system and the microhabitat where the individual was found was noted. To compare the observed abundance between sites, we calculated the rate of encounter [23] .…”