An international team of scientists has described seven new species of Madagascar's elusive diamond frogs (Rhombophryne), revealing that one of the island's most mysterious groups of amphibians is even more diverse than previously thought.
Knowing where species occur – and even recognising that they are distinct species – is fundamental to understanding biodiversity and protecting it. Combining museum collections, fieldwork and advanced DNA analyses, the researchers uncovers previously hidden diversity and resolves a long-standing taxonomic puzzle. By clarifying the identities and distributions of these secretive frogs, the research provides an important foundation for future conservation efforts in Madagascar's rapidly disappearing forests.
"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.
Diamond frogs are among Madagascar's most distinctive amphibians. Some species are remarkably round, resembling the rain frogs of mainland Africa, and spend much of their lives hidden beneath the forest floor. Others are long-legged moss dwellers or strong-bodied terrestrial species. Although most appear brown at first glance, several conceal flashes of orange or striking white or black markings on their thighs and lower backs, which may serve to startle predators.
These secretive habits make diamond frogs some of Madagascar's least-studied vertebrates.
Twelve years in the making
The project began more than twelve years ago after researchers repeatedly encountered frogs that clearly represented undescribed species. Resolving their identities proved challenging because scientists could not confidently match historical species names with modern genetic lineages.
"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.
The breakthrough came through museomics – the sequencing of DNA from historical museum specimens. By combining genetic data from these historical collections with newly collected material, alongside analyses of external and skeletal anatomy and frog calls, the researchers were able to match historical names to the correct evolutionary lineages and resolve decades of taxonomic uncertainty.
Historical museum specimens proved essential for resolving the identities of several 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.
A foundation for conservation
The study represents a close collaboration between researchers and institutions in Madagascar and Europe. It also demonstrates how closely biodiversity research and conservation are linked. Many diamond frogs inhabit forests that are increasingly fragmented by deforestation, yet scientists still know remarkably little about the biology of many species.
"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 informing conservation planning in Madagascar. During a protected area planning workshop held in March 2026 as part of the country's Biodiversity 30x30 Program, several of the newly described species – including Rhombophryne quentini – contributed directly to proposals to strengthen and expand protected areas.
Even after describing seven new species – bringing the total number of known Rhombophryne species to 27 – the researchers conclude that additional, currently unnamed species almost certainly remain to be discovered and scientifically described.
Although the study helps to answers many long-standing questions, Dr. Mark D. Scherz believes it is only the beginning.
"Every newly described species represents millions of years of unique evolutionary history. The more we learn about Madagascar's remarkable amphibians, the clearer it becomes that there is still an enormous amount left to discover," he said.
