Ben Tapley, ZSL’s Curator of Herpetology, describes the discovery of a new frog species in Vietnam.
As a child I was fascinated by amphibians. The sheer array of species and their diverse forms and behaviours was something that captivated me – a fascination which remains to this day. In my lifetime the number of amphibian species has approximately doubled and there are now over 7,700 species described by science. Some researchers estimate that there may be a staggering 12,000 amphibian species in total.
Over the past couple of decades however, amphibian declines have been making the headlines; nearly half of amphibian species are threatened with extinction and they are the most threatened vertebrate group on the planet. This appears at odds with the rate of new species descriptions, so why are so many new amphibian species being described?
Many currently recognised amphibian species are in fact species complexes; this means that an apparently widely distributed species is in fact many different species that appear to be similar in appearance. With the rise of integrated taxonomy (the use of multiple methods to delineate a species) it has become apparent that we have grossly underestimated amphibian species diversity.
One region that has been particularly rich in amphibian species discovery is mainland Southeast Asia, particularly Vietnam. More than 70 new species of amphibian have been described from Vietnam in the past 12 years alone and there are many more awaiting description.
In 2015, ZSL in partnership with Hoang Lien National Park's Centre for Conservation and Rescue of Organisms and the Australian Museum we began a project aimed at conserving two newly described and highly threatened amphibian species that were only known from the Hoang Lien Range, a stunning rugged mountain range in the far north of the country which extends into China. This mountain range has long attracted amphibian biologists to its misty slopes and approximately 80 amphibian species have been recorded in the area. It was during recent work in this area that we encountered a diminutive small brown frog that didn't quite look like any described species.
One evening we were en route to a small stream where we had decided to carry out an amphibian survey; we were on the back of mopeds eager to get to our carefully chosen field site. We were passing through a patch of exceptionally degraded forest and heard something that we thought could be a horned frog calling. We parked up the bikes and began exploring the roadside. After half an hour of crawling through wet grass we finally managed to locate a single male leaf frog emitting an insect like call only a couple of meters from the road. Just 3cm in length it had vivid red thighs and appeared to resemble a species that had been described from eastern China in the 1920s, but something about its shape and colouration was not quite right.
We diligently recorded the vocalisations and took the samples that were required to determine whether or not this species was new to science. Genetic samples and the call recording were analysed by the team at the Australian Museum and with the assistance of the team at the Natural History Museum in London I began the painstaking task of comparing our frog to all other related frogs, making careful notes of the combination of characteristics that could be unique or make it stand out from other frogs in this group.
Soon it was clear that we were in fact dealing with a species new to science. The vivid orange red colour of the thigh was one of the most obvious characters that differentiated this species from its relatives and so we named it Megophrys rubrimera - the red-thighed horned frog.
Why is this new finding significant? For me this species epitomises the problems faced by amphibians globally. The species, being new, is of course like the majority of amphibian species poorly known. And being small and predominantly brown does not attract the same attention as being furry, orange and stripy! This tiny frog had been encountered by biologists working in the region over 15 years ago but no one had taken the time to pay it much attention and it had been overlooked.
Furthermore it is probable that this new species is highly threatened, as the only forest patches it is known from in Vietnam are extremely degraded and encroached upon by agriculture. It has a particularly restricted range and likely only occurs in a small area (about 385 km2 to be precise) and is therefore very probably in need of conservation attention.
Without a name it is extremely difficult to place a species on the conservation agenda, but now we finally know some basic information about this species (where it lives, what it looks like, what it sounds like and a little about the larval stage), the red-thighed horned frog can now at least be incorporated into the conservation decision making process for this area. We hope that now we know about it, this small brown frog will no longer be overlooked, and will continue to call from road side verges (and forests!) in this area for many years to come.
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