Lost for more than a century: the rediscovery of Alsodes vittatus (Philippi, 1902) (Anura, Alsodidae), one of the rarest and most elusive amphibians from Chile

The legacy of the 19^th-century naturalist Rudolph Philippi to the taxonomy of Chilean amphibians has been controversial since most of the species he described in 1902 have been questioned or invalidated. Here, we describe the rediscovery of <i>Alsodesvittatus</i>, a species that was not observed for 130 years after being collected, in three places very close to the type locality in the Andean foothills of the La Araucanía Region, Chile. The species was identified phenotypically by the vertebral line of some individuals, which turned out to be an intrapopulationally polymorphic trait. A phylogenetic analysis with mitochondrial genes, including most of the species of the genus, showed that the discovered populations of <i>A.vittatus</i> are paraphyletic with respect to the only individual of <i>A.neuquensis</i> included. We also describe populations from another area where <i>A.vittatus</i> was searched in the past, which we assigned here to <i>A.igneus</i> due to its geographic location and phylogenetic and phenotypic affinity. All these populations are part of two well-supported clades, but their relationships with nearby species (e.g., <i>A.norae</i> and <i>A.barrioi</i>) remain uncertain. These results ratify that the diversity and phylogenetic relationships of the genus in the Chilean Andes, particularly in the La Araucanía Region, are not yet well established. We discuss the possibility that <i>A.vittatus</i> and <i>A.neuquensis</i>, known until now only in Argentina, are the same species, and suggest downgrading the conservation status of <i>A.vittatus</i> from Critically Endangered to Endangered, considering the information from the new localities discovered.