Scientists have identified a new genus and species of true toad from a single specimen found in the high forests of Mount Kenya, an extinct volcano in Kenya and the second-highest peak in Africa, after Kilimanjaro. Contrary to the prevailing belief that most of Kenya’s amphibian species originated after volcanic activity subsided millions of years ago, the new species — named the Kenyan volcano toad (Kenyaphrynoides vulcani) — may date back as far as 20 million years, making it significantly older than the volcanic formation of Mount Kenya itself.

Artistic rendition of Kenyaphrynoides vulcani (A), drawing of a dorsal view of the left hand of the holotype (B), and dorsal (C) and ventral (D) photographs of the holotype prior to preservation. Image credit: Liedtke et al., doi: 10.1093/zoolinnean/zlad160.

“Many of Kenya’s mountains are volcanic or geologically comparatively new, so to find an ancient lineage that has persisted for millions of years is mind-blowing,” said Dr. Simon Loader, principal curator of vertebrates at the Natural History Museum, London.

“It’s a real conundrum to figure out how it got here.”

“While we’re not certain, it seems like it might once have had a wider distribution and as the climate changed over the past 10’s of millions of years, it tracked the tropical forest as it moved, with the toad’s final destination being the top of Mount Kenya.”

The discovery of the Kenyan volcano toad challenges the notion of the Kenyan Interval, a term used to describe the stark contrast in amphibian diversity between Kenya and its neighboring countries.

While Ethiopia and Tanzania have long been biodiversity hotspots for amphibians, Kenya’s geological history, and the frequency of tectonic activity, has made it a challenging place for these creatures to thrive.

The unique characteristics of Kenyaphrynoides vulcani suggest that the Kenyan Interval may not be as straightforward as previously believed.

When the toad was first discovered in a pitfall on Mount Kenya back in 2015, it already appeared to be very different from the species that are normally found in the region.

“We were really surprised to see this animal — it didn’t look like anything we had seen before but resembled something we knew from Tanzania called Churamiti maridadi, a forest tree toad from the rainforests of the Ukaguru mountains,” said Dr. Patrick Malonza and Dr. Victor Wasonga, curators at the National Museums of Kenya.

Kenyaphrynoides vulcani’s distinct features include a smaller size, a more frog-like body, and distinctive green and brown markings.

Its genetic and morphological differences from other known toad species have led to its recognition at the genus level.

Clues from its physical characteristics, such as enlarged fingertips suggest it may be a climber.

Its thumbs also have sharp points known as nuptial spines which are found in many male frogs and toads, as they help the male grab onto a female and stimulate them into breeding.

“These forest toads found in mountains in East Africa are unusual and don’t look like a typical toad,” said Dr. Hendrik Müller, a researcher at the Martin-Luther-University Halle-Wittenberg.

“More interestingly, several are known have an unusual breeding strategy called ovo-vivipary.”

“In ovo-viviparity the eggs hatch inside the female. This means that the young emerge from the mother as small toads, rather than as tadpoles.”

The discovery is reported in a paper in the Zoological Journal of the Linnean Society.

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H. Christoph Liedtke et al. A new genus and species of toad from Mount Kenya illuminates East African montane biogeography. Zoological Journal of the Linnean Society, published online November 7, 2023; doi: 10.1093/zoolinnean/zlad160