Two new species of worm salamanders described from the Andes

Salamanders are a diverse group of amphibians found mainly in the northern hemisphere.

The largest group of salamanders are the lungless salamanders, known more formally as the Plethodontidae. These amphibians have done away with their lungs entirely and instead breathe through their skin and the lining of their mouths.

Some of these salamanders live on the ground among the leaf litter, caves and streams, while others have taken to the trees and become arboreal. Another group make their living underground.

Burrowing through the soil and eating any invertebrates they find on their way has caused many of the species within this group to become incredibly long and snake-like, with tiny legs and reduced digits on their hands. This has given rise to their common name of worm salamanders.

Because of their subterranean lives these little amphibians are not particularly well studied. But a series of expeditions that started near a newly protected patch of Ecuadorian rainforest and ended up in the Museum's collections has now resulted in two new species of worm salamanders being described.

Dr Jeff Streicher, the Senior Curator in Charge of Amphibians and Reptiles at the Museum, helped an international team led by Carolina Reyes-Puig of San Francisco University of Quito to describe both of these new species, including finding one of the new species in the Museum's own collections. The research has been published in the journal Peer J.

'These salamanders are very rarely encountered because they spend most of their lives underground,' explains Jeff. 'They are absolutely weird.

'I mean their hands and feet look like they are wearing mittens.'

Two new species for the price of one

The first of the new species (Oedipina villamizariorum) was found while Jeff's colleagues were searching for an entirely different type of burrowing amphibian known as caecilians. As they dug through the ground on the hunt for these, they came across a worm salamander. 

Once it was taken back to the lab and its DNA was tested by Dr Santiago Ron, it was clear that they had a new species on their hands. To compare it with other closely related species, Jeff was asked to look through the collections at the Museum. 

'Comparisons to similar specimens led to the discovery of the second species, which is only known from a single specimen that is in our collection registered at the Museum in 1901,' explains Jeff. Amusingly, one of Jeff's colleagues Dr David Wake actually looked at this very specimen in 2011 and even back then suspected that it was not quite what it seemed.

'Dave thought that the specimen was probably something new, based just on the outside of its body,' says Jeff. 'But when we scanned it, it turns out that the salamander also has a novel skull character that is not present in any other species in this genus.'

While they haven't attempted to extract any DNA from the specimen, the skull is so distinctive that it was used as unequivocal proof that they had a second new species, now called Oedipina ecuatoriana.

The Great Interchange

While in the UK there are only a couple of species, known more usually as newts, salamanders are most diverse in North and Central America, with the number of species decreasing as they get closer to the equator. 

This distribution is rather curious, because as a general rule the number of species tends to increase from the poles down towards the topics.

'In plethodontid salamanders we see the inverse with the highest diversity at higher latitudes,' says Jeff. 'So actually it is in the mountains of North and Central America where most species of plethodontid salamanders are found. As you go further south and you get to South America we observe fewer and fewer species.

'These two new species are now the furthest south their genus has been found.'

This is likely a result of historic geography, as North America and South America have been mostly separated by a wide channel of sea throughout geologic history. This stretch of water was last closed when the volcanic Isthmus of Panama rose up and bridged the two continents around three million years ago. 

When this happened it allowed for what is known as the Great American Interchange. During this event, animals such as giant ground sloths and marsupials went north, while others such as mammoths and some salamanders moved south.

Because salamanders are generally small and don't tend to move large distances, it is likely that few species have managed to make it that far down into South America.

The Dracula Reserve

The two new species both come from northern Ecuador, suggesting that there is likely a hidden diversity of this hard-to-find group of salamanders making their way beneath the trees and bushes of the Andes Mountains.

'There are probably many undescribed species,' says Jeff. 'That would make sense because they are tiny and so they can't move around very much. The salamanders probably stay in a small area all year round as it is a relatively stable environment.

'Fingers crossed that someone will come across more in the field so that we will get new insights into their biology.'

There is still a lot that is unknown about these animals, but it is hoped that some of that detail might one day get filled in. The first species was found near a newly formed protected area called the Dracula Reserve that is managed for the non-profit organization EcoMinga Foundation, named not for the blood thirsty count but the genus of orchids which it was set up to protect.

This will hopefully mean that more scientists will be able to safely visit this region and start to study the animals and plants that live there in increasing detail.