Three new species of toads have been discovered in Tanzania that give birth to live cubs

An international team of biologists has described three new species of tree toads from Tanzania that do not lay eggs but give birth to fully formed cubs. This is the rarest phenomenon among amphibians - this mode of reproduction is found in less than 1 per cent of all frog and toad species. The results are published in the journal Vertebrate Zoology.

The researchers studied the collections of the Natural History Museum in Berlin, where specimens collected more than 120 years ago are kept. Using modern genetic methods known as "museomics" (museomics ), scientists were able to isolate DNA from the oldest exhibits and determine which species they belonged to. This allowed them to clarify the family relationships and describe three previously unknown species of tree toads of the genus Nectophrynoides, which live in the Eastern Arc Mountains of Tanzania.

"Back in 1905, the German zoologist Gustav Tornier reported a startling discovery - a toad that gives birth to live cubs. We now know that such species do exist and there are more of them than thought," explained study co-author Professor Mark Schertz from the Natural History Museum of Denmark.

For a long time the only known species of viviparous toad was thought to be Nectophrynoides viviparus, but modern research has shown that this name hides a whole group of species. Three of them - Nectophrynoides luhomeroensis, N. uhehe and N. viviparus sensu stricto - are officially recognised as new to science.

As biologist J. Christoph Liedtke of the Spanish National Research Council explains, live birth among amphibians is an extremely rare strategy. Apart from African tree toads, only a few species from South America and Southeast Asia reproduce in a similar way.

"Live birth is one of the most amazing displays of evolution in amphibians. These findings emphasise how important it is to conserve the rainforests of East Africa, home to these unique animals," said Simon Loader of London's Natural History Museum, co-author of the paper.

The Eastern Arc Mountains are considered a biodiversity hotspot, home to many endemic species found nowhere else on Earth. However, scientists warn that these ecosystems are being rapidly destroyed by deforestation and climate change. Already several species of the genus Nectophrynoides are on the brink of extinction: one species is extinct in the wild and another has not been observed since 2003.

"If we lose these forests, we will also lose one of the most unusual phenomena in the amphibian world - live births in toads," says John Lyakurwa of the University of Dar es Salaam, who was involved in the study.