Abstract
High Andean environments of central Chile (32°–38°S) are inhabited by several endemic species of the genusAlsodes. Two of them,A.pehuencheandA.hugoi, have geographic distributions restricted to their type locality and surroundings. The Chilean government classifiesA.pehuencheas Critically Endangered (like the IUCN) andA.hugoias Vulnerable. In this study we report 16 new localities ofAlsodes, corresponding to first order streams, located in the Andes of Chile between 35°58’ and 36°32’S (1800–2470 m). In some of these sites, adults and juveniles morphologically similar toA.pehuencheandA.hugoiwere observed, as well as specimens ofAlsodesthat could not be identified by their external morphology. A Bayesian phylogenetic analysis with mitochondrial sequences (cytochrome b) was performed to identify the new populations to species level. All populations around 36°S belong toA.pehuenche, while most of those located south of that area would beA.hugoi. The exception is Cajón de Plaza (36°23’S), where specimens with sequences ofA.hugoiorA.pehuenchecoexist, whose taxonomic status could not be determined. These findings imply not only a westward range extension ofA.pehuenchein Chile of about 14.5 km and ofA.hugoiabout 100 km southward, but also that practically all the first order streams of the Andes of central Chile would be inhabited by populations ofAlsodes. Both results demonstrate the scarce biogeographic knowledge of the genus in the Andes, which has important implications for its conservation at local and species levels.
Highlights
The amphibian fauna of the Andes of southern South America (Chile and Argentina) is relatively poor in comparison to tropical high-altitude environments (Duellman 1979, 1999)
Some of the adults and juveniles were tentatively identified as A. pehuenche or A. hugoi by their external characters (Table 1), but most specimens from Vegas de Miranda could not be identified to species level (Fig. 2D)
The localities of A. pehuenche reported here constitute the third and widest distribution extension since the species was described (Cei 1976), more than doubling the known distribution until 2013 (Correa et al 2013). The occurrence of this species is extended to another hydric system in Chile (Lo Aguirre Grande and Lo Aguirre Chico), not connected directly to Laguna del Maule (Fig. 1)
Summary
The amphibian fauna of the Andes of southern South America (Chile and Argentina) is relatively poor in comparison to tropical high-altitude environments (Duellman 1979, 1999). Alsodes is the most diversified of these genera, with five species (A. montanus (Lataste, 1902), A. tumultuosus Veloso, Iturra & Galleguillos, 1979, A. hugoi Cuevas & Formas, 2001, A. pehuenche Cei, 1976 and A. nodosus (Duméril & Bibron, 1841)) present in the western slopes (Chile) between 33° and 36°S (Charrier et al 2017). Four of these species are endemic to Chile, since A. pehuenche is present in Argentina in a small area around the border between these countries (Valle Pehuenche, its type locality, 36°S) (Corbalán et al 2010, Correa et al 2013).
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