Distribution and population structure of Ambystoma altamirani from the Llano de Lobos, state of México, Mexico

Ambystoma altamirani is an endangered salamander found in high mountain streams in the vicinity of Mexico City, and its populations might be threatened by urban growth. Here we report our research on a previously unstudied population of A. altamirani at the Llano de Lobos in the Sierra de las Cruces. The study ran from September 2018 to September 2019. The number of observed individuals was relatively constant across months. The only months when we observed gilled adults were February and July, and the only months when we saw juveniles without gills were January, February, and August, suggesting that the transformation of juveniles to adults takes place twice a year, once in January–February and once in July–August. We observed egg masses in December and January, and larvae from March to May and also in July. The sex ratio was significantly female-biased (about 2:1). We observed A. altamirani at 3 of the 25 permanent sites during the study period. Our comparison of the characteristics of occupied sites with those of unoccupied sites suggests that availability of sunlight (i.e., less cover) and low levels of human impact are important for occupancy by A. altamirani. These findings are consistent with observations of other populations of A. altamirani, suggesting that these characteristics might be important in their management and conservation.