Some of Madagascar’s hardest-to-find frogs have been keeping a long secret.

An international research team has identified seven previously undescribed species of Madagascar’s diamond frogs, or Rhombophryne, using field observations, museum specimens and DNA analysis. The findings push the number of known Rhombophryne species to 27 and resolve a taxonomic problem that had remained unsettled for years.

“Diamond frogs have been hiding their diversity beneath our feet,” said Dr. Mark D. Scherz, Curator of Herpetology at the Natural History Museum Denmark and lead author of the study. “Many species spend most of their lives beneath the leaf litter, and even when they emerge they can look deceptively similar,” he added.

The researchers said accurately identifying species and understanding where they live is key to measuring biodiversity and protecting it. By determining which frogs belong to which species and mapping where they occur, the team said it has created a stronger scientific basis for conservation in Madagascar, where many forests are rapidly disappearing.

Diamond frogs are among Madagascar’s most distinctive amphibians. Some species are extremely round and resemble rain frogs from mainland Africa, spending much of their time concealed beneath the forest floor. Others have long legs and live among moss, while some are sturdier frogs adapted to life on the ground.

Most diamond frogs look brown at first, but several species have vivid markings that stay hidden until the frogs move. These include bright orange flashes or bold white and black patterns on the thighs and lower back. Researchers think these markings may help startle predators.

The project began more than 12 years ago, when scientists repeatedly encountered frogs that appeared to represent species that had never been formally described. Matching older species names with the genetic lineages found in modern specimens proved difficult.

“When I started this project twelve years ago, we already knew there were several species waiting to be described, and almost every expedition to Madagascar revealed another one. Some were relatively straightforward to describe, but others were complicated by uncertainty surrounding older species names. Untangling that puzzle took years,” Scherz said.

A major breakthrough came from museomics, which uses DNA sequencing on historical museum specimens. The team compared genetic information from old collections with DNA from newly collected frogs, and also examined external features, skeletal anatomy and frog calls.

Those lines of evidence allowed the researchers to connect historical species names with the correct evolutionary lineages and clear up taxonomic confusion that had persisted for decades. Museum collections played a central role in establishing the identities of several of the species.

“Museum collections are far more than archives of the past – they are essential scientific resources for understanding biodiversity today,” said Dr. Alice Petzold of the University of Potsdam, who led the museomics work. “By sequencing historical specimens, including the original type specimens, we were able to answer questions that have persisted for generations,” she added.

The study involved scientists and institutions in Madagascar and Europe. The researchers said it also shows a direct link between biodiversity research and conservation, as many diamond frogs live in forests that are becoming increasingly fragmented by deforestation.

“For many species, we still know almost nothing about their breeding biology, population sizes or ecological requirements. Without that knowledge, it becomes much more difficult to assess their conservation status and protect them effectively,” said co-author Dr. Andolalao Rakotoarison of the Institut d’Enseignement Supérieur de Soavinandriana Itasy, Madagascar.

The findings are already feeding into conservation planning in Madagascar. At a protected area planning workshop in March 2026, held as part of the country’s Biodiversity 30×30 Program, several of the newly described frogs, including Rhombophryne quentini, directly informed proposals to strengthen and expand protected areas.

The study appears in Vertebrate Zoology.

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