Alsodes vittatus: Rare frog species rediscovered in Chile after 130 years

For more than a century it was considered lost, but now it is back: Alsodes vittatus, an endemic amphibian species from Chile, has been rediscovered in the Región de La Araucanía. There had been no confirmed sightings of this rare frog species for around 130 years. Its rediscovery could not only lead to a reassessment of its conservation status, but also raises new questions about genetic diversity and taxonomic classification.

A forgotten frog and its controversial discoverer

The story of A. vittatus begins with an expedition in 1893. The French entomologist Philibert Germain, who actually specialized in insects, also collected amphibians and other wildlife during a research trip in the Chilean Andes. At the Hacienda San Ignacio de Pemehue, he took samples along a river, including three frogs that were later described as a new species by the German naturalist Rudolph Philippi.

Philippi, who played a key role in the taxonomy of Chilean amphibians, initially named the species Cyclorhamphus vittatus in 1902. Later revisions transferred it to the genus Alsodes. But Philippi’s scientific legacy is not without controversy: Many of the amphibian species he described were later called into question or declared invalid. The rediscovery of A. vittatus shows, however, that his work still provides valuable clues for research today.

Why did the species remain undiscovered for so long?

After its original description, A. vittatus fell into obscurity. Despite targeted searches in the 1990s and early 2000s, the species could not be documented again. Only decades later did it become clear that earlier expeditions had probably searched in the wrong place.

A team led by the herpetologists Claudio Correa, Edvin Riveros-Riffo and Juan Donoso from the University of Concepción took up the challenge again. Using historical records, the scientists reconstructed Germain’s route from 1893. They found that earlier searches had begun on the wrong side of the estate—one possible reason why the species remained undiscovered for so long. Environmental changes or imprecise historical information had probably made orientation more difficult.

The breakthrough: A targeted search succeeds

With this new insight, the team systematically searched the correct region in 2023 and 2024—successfully. Several populations of A. vittatus were documented. The frogs were discovered at three sites close to one another along streams in the Andean foothills, more precisely in the headwaters of the Lolco and Portales rivers.

The variability in coloration and patterning was especially remarkable: While some animals had a distinctive pale dorsal stripe, in others it was only weakly developed or absent altogether. This diversity raised new questions about intraspecific diversity.

DNA analysis: Is it really A. vittatus—or a new species?

Modern DNA analyses confirmed the identity of the finds, but a surprising contradiction emerged: While Philippi had described the original specimens as “intensely black,” the rediscovered frogs now show a broad color palette ranging from olive green to brown. This could indicate that A. vittatus has greater genetic diversity than previously assumed—or that it may be a previously unknown, closely related species.

An analysis of mitochondrial DNA also showed that the newly discovered populations of A. vittatus are paraphyletic with respect to A. neuquensis. This means that they cannot be clearly distinguished genetically from this Argentinian species. A central question for research is therefore: Is this a single species that has developed differently on both sides of the Andes, or do two separate species exist here? Further studies are needed to resolve this taxonomic uncertainty.

Habitat and threats

The rediscovered populations of A. vittatus inhabit the temperate forests of the Andean foothills in the La Araucanía region. They were found near streams in areas with Nothofagus and Araucaria forests.

But the habitat of this species is threatened. Intensive land use—especially livestock farming, deforestation and the spread of invasive species such as introduced trout—is putting pressure on the populations. Trout prey on tadpoles and could drastically reduce the frogs’ reproductive success.

Another threat is the expansion of pine plantations. These monocultures alter the water balance and can displace the natural habitats of A. vittatus through soil acidification and changed microclimates.

Added to this are the impacts of climate change: Decreasing snow amounts and altered precipitation patterns could affect the sensitive aquatic ecosystems that are essential for the reproduction and survival of A. vittatus. If the species does in fact contain a previously unrecognized diversity of genetic lineages, some populations may be better adapted to these environmental changes than others—another question that future research will have to clarify.

Importance for species conservation

Until now, A. vittatus has been classified by the IUCN as “Data Deficient”. The current discovery could now lead to a reassessment of its threat status. In view of the threats from human disturbance, invasive species and climate change, the researchers propose classifying the species as “Endangered”.

It is particularly concerning that A. vittatus is not known from existing protected areas. This means that its survival depends entirely on unprotected, potentially threatened habitats. The scientists therefore call for the designation of new protected areas and greater efforts to preserve the sensitive ecosystems in which this rare amphibian species survives.

Scientific publication on the rediscovery

The results of the rediscovery of Alsodes vittatus were published in a scientific study. The researchers Claudio Correa, Edvin Riveros-Riffo and Juan Donoso presented their findings in the journal ZooKeys (2025). Their publication describes not only the localities and genetic analyses, but also discusses open questions about species validity and the taxonomic classification of the newly discovered populations.

The rediscovery of Alsodes vittatus is not only an important find, but also raises fundamental questions about the identity and genetic diversity of the species. Whether it really is Philippi’s lost species or whether science is dealing here with a previously unknown species will only become clear through future research.

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Source

• Correa, C., Riveros-Riffo, E., & Donoso, J. (2025). Rediscovery of Alsodes vittatus after 130 years: Phylogenetic implications and conservation status update. ZooKeys, 1230, 1–20. https://doi.org/10.3897/zookeys.1230.135523