A remarkable find in Tanzania has revealed three previously unknown species of tree toads, all exhibiting the rare and fascinating ability to give birth to live young. This discovery, made by an international team of researchers, underscores the ongoing significance of natural history collections and highlights the urgent need for conservation efforts in the region. The findings, published in the open-access journal Vertebrate Zoology, challenge conventional understandings of frog reproduction and shed light on the incredible diversity found in East Africa’s Eastern Arc Mountains.
Challenging the Standard Narrative of Frog Reproduction
Most textbooks depict a straightforward lifecycle for frogs: eggs hatch into tadpoles, which then undergo metamorphosis into froglets and eventually mature into adults. “That’s the standard paradigm,” explains Assoc. Prof. Mark D. Scherz, Curator of Herpetology at the Natural History Museum of Denmark and co-author of the study. “But there is actually a lot of diversity in amphibian reproduction.”
A Century-Old Mystery Solved Through ‘Museomics’
The story of live-bearing frogs dates back to 1905 when German researcher Gustav Tornier presented his discovery of a toad from Tanzania giving birth to live young to the Royal Prussian Academy of Sciences in Berlin. The key specimens used in Tornier’s original work, housed at the Museum für Naturkunde in Berlin, were instrumental in this new study. Utilizing cutting-edge techniques known as “museomics,” researchers were able to extract DNA from these century-old specimens, clarifying their origins and boosting the team’s confidence in their findings.
“Some of these specimens were collected over 120 years ago,” says Dr. Alice Petzold of the University of Potsdam, who conducted the museomics analysis. “Our museomics work was able to reveal exactly which populations those old specimens belonged to.”
Live-Bearing: A Rare Adaptation
While initially the only known live-bearing frog species, it is now understood that these Tanzanian “Tree Toads” (genus Nectophrynoides ) and their relative, the Nimba toad (Nimbaphrynoides occidentalis ), reproduce this way. This method is exceptionally rare, practiced by fewer than 1% of all frog species worldwide, making these newly discovered species particularly intriguing.
Uncovering Hidden Diversity
Recent phylogenetic analyses hinted at previously unrecognized diversity within the tree toad group. Researchers combined extensive museum visits, examination of hundreds of preserved specimens, and the application of “museomic” methods to extract DNA to gain a clearer picture of their morphology and identify the new species.
An Imperiled Biodiversity Hotspot
The new species inhabit the Eastern Arc Mountains of Tanzania, an area recognized as a biodiversity hotspot where many species are found nowhere else on Earth. However, these mountains and their lush forests are facing serious threats. Habitat fragmentation, driven by deforestation, is negatively impacting the region’s biodiversity, including these unique toads.
“The forests where these toads are known to occur are disappearing quickly,” says John V. Lyakurwa, a researcher at the University of Dar es Salaam and a co-author on the study. Most of the tree toads are already critically endangered. Tragically, one species, Nectophrynoides asperginis, is already extinct in the wild, while another, Nectophrynoides poyntoni, hasn’t been observed since its discovery in 2003.
These discoveries highlight both the diversity of live-bearing toads and the urgent importance of protecting East Africa’s forests.
This remarkable find emphasizes the value of natural history collections and the need for continuous exploration and conservation to fully understand and protect the planet’s biodiversity. By safeguarding these vulnerable forests, we can ensure that these extraordinary toads—and the unique reproductive strategy they embody—persist for future generations to study and appreciate
