A team of researchers has identified a new species of frog, named Dryadobates erythropus, from a single specimen that has been preserved for over six decades. The specimen was collected in 1963 by American herpetologist Doris M. Cochran during her research in Curitiba, Brazil. Unfortunately, this species is likely extinct in the wild, as no other specimens have been found.
The findings were published in the journal Zootaxa by a collaborative effort between researchers from the University of São Paulo (USP) and the Smithsonian Institution. The only known specimen is housed at the Smithsonian’s National Museum of Natural History in Washington, D.C. This frog, measuring approximately 14 millimeters, is classified as “probably extinct” due to the destruction of its habitat and the lack of additional sightings over the past 60 years.
The Dryadobates genus includes at least 13 species, with four having gone extinct between the 1960s and 1980s. Taran Grant, a professor at USP and the first author of the study, noted, “The living species of this genus are diurnal frogs, quite abundant, which would be easy to find in the wild. Given that the habitat of D. erythropus has been destroyed and that no other specimen has been collected in extensive surveys in various locations in São Paulo and Paraná, it’s most likely extinct.”
Historical Context and Discovery
The name Dryadobates draws from Greek mythology, referring to Dryades, tree nymphs, while the suffix “bates” translates to “one who walks.” The species name, erythropus, means “red foot,” a nod to rural workers in northern Paraná who worked barefoot on the region’s reddish soil. Several other species within this genus have been named for the Brazilian states where they were found, with two of those also believed to be extinct.
To pinpoint the precise location of where the frog was collected, Grant examined additional records alongside the specimen’s original label. The Smithsonian possesses an extensive archive related to its researchers, which includes Cochran’s travel diary. This diary proved instrumental in establishing the frog’s collection location, as it contained details about the environment in which the frogs were found.
Grant explained, “Based on what we knew about the distribution of this group, when we saw the reference to Curitiba, we thought it might have been confused with an animal collected in Rio de Janeiro. However, the animal’s characteristics do not match those Cochran described as having been collected in a lagoon in Rio de Janeiro. The Tarumã notes from January 9, 1963, clearly indicate that two frogs were captured in a ‘large field full of anthills and cow-chewed bushes.’”
The location described in the diary is approximately 550 kilometers south of the closest known species, D. olfersioides, which is also extinct. This distance suggests that there may have been other undiscovered populations of the genus in the region.
Challenges in Genetic Analysis
Of the seven species of Dryadobates formally described, three were identified using historical DNA (hDNA) techniques. These methods can recover genetic material from specimens preserved for over 100 years. Grant attempted to extract hDNA from the 1963 specimen but faced challenges.
Despite permission from the museum curator to remove a small tissue sample for analysis, the effort yielded insufficient genetic material, mostly contamination from human DNA and bacteria. Grant speculated that the frog likely died before being preserved in alcohol, as indicated by the presence of sand on its skin. This suggests that the DNA began degrading much earlier than it would have if proper preservation methods had been employed.
Although the specimen’s condition hindered genetic identification, the researchers were able to classify the frog as a new species based on its morphological characteristics. Grant emphasized the importance of this work, highlighting not only the need to protect natural habitats but also paying tribute to the contributions of Cochran and Doris Blake, both of whom made significant strides in their respective fields.
He concluded, “If it weren’t for them, we wouldn’t know that we once had this species.”
As research continues to evolve, there is hope that advances in technology may eventually allow for further genetic identification of this and other long-lost species.
