The poison frog that fooled scientists for decades
Researchers discovered that a poison frog species described decades ago was based on a mix-up involving the wrong museum specimen. The frog tied to the official species name turned out to be brown, not the colorful animal shown in the original photo. After tracing old records and images, scientists corrected the error and reclassified the frog as part of an already-known species. The case underscores how vital museum collections are—and how even small mistakes can ripple through science for years.
Scientists at the University of Kansas Biodiversity Institute and Natural History Museum recently uncovered a mistake that dates back decades involving a poison frog specimen from Peru. The frog had been incorrectly identified and designated as a holotype, which is the single preserved specimen used to officially define a species. While modern taxonomy may also rely on supporting materials such as photographs or genetic information, the holotype remains the primary reference point.
The research team published its findings in the journal Zootaxa.
Why Holotypes Matter in Species Science
"When you describe a species, you assign one specimen that bears the name of that species," said lead author Ana Motta, collection manager of herpetology at the Biodiversity Institute. "If I find something else later that looks like that species, I need to go to the holotype and compare things to know if that new population belongs to that species or is something else. So, the holotype is the specimen that represents the species."
This system ensures that scientists around the world are referring to the same organism when discussing a species.
A Photo, a Catalog Number, and a Critical Mix-Up
The error traces back to 1999, when a researcher encountered a published photograph of a brightly colored frog from the Peruvian rainforest near the Ecuadorian border. Unable to match it to a known species, he described it as new using only the photograph of a specimen housed in the University of Kansas herpetology collection. The frog was logged under specimen number KU 221832 and given the scientific name Dendrobates duellmani.
"Each specimen gets a catalog number. It's like a barcode," Motta said. "All photos, genetic data, calls, whatever we have associated with that specimen are linked to that catalog number. When the researcher saw the photo, instead of asking for the specimen, they asked for just the catalog number, and they were given the wrong catalog number that belonged to another specimen. So, they associated the wrong specimen with the new species description. The true specimen was real. It just had another catalog number."
How the Error Was Discovered
The problem came to light years later when herpetologists visiting the Biodiversity Institute asked to examine the holotype while studying related frog species.
"We had visitors -- experts in this frog group -- studying many species," Motta said. "Because the holotype represents the species, they wanted to look at the holotype to understand other populations. When they got the specimen with the described number, they realized: This is not it. The frog is very colorful, and the numbered one was brown."
That discovery prompted Motta and her colleagues to investigate how the mistake occurred.