| Articles | Herpetology | Bambu | By Alejandro Arteaga — May 2011 |
Discovering Ecuador's five-hundredth amphibian
500 species of amphibians may seem like too much for a country roughly the size of the state of Colorado. However, 500 may be just half the number of species that actually exist in Ecuador. That missing half needs to be described; otherwise, thousands of wonderful amphibians, which are the most threatened group of vertebrates on the planet, may go extinct before we even find out about their existence.
In this sense, the story of the newest addition to Ecuador's list of frogs may prove helpful, as it may hold the clues to discover those frogs yet unknown to science, and therefore foster interest in their conservation.
Naming a single species is a small step, but it's the first one towards the long-term conservation of that species, so how is it done? Let's look at the example of Ecuador's five-hundredth described amphibian: the Bamboo Rain-Peeper (Pristimantis bambu).
Finding the Bamboo Rain-Peeper was like discovering a secret, a deeply held secret. It all started in February 2008, when me, and my family, were kindly invited by Stuart White and his wife, Patricia to stay at their hacienda (actually a protected area called the Mazar Reserve) at the southern portion of the Sangay National Park.
From the very first moment, I became fascinated with the landscape at Stu's property: it was a combination of pristine montane forest, green pastures and alpacas. Even better, the place looked promising for amphibians (with moist, well-conserved forests). I recognized its potential right away, because I knew that most of Ecuador's unknown amphibians were still hidden in isolated forests in the Andes; specially in the southern Andes, a region in which topographic and ecological complexity has favored speciation, particularly among Rain-Peepers of the genus Pristimantis.
Unfortunately, the weekend was soon over, and I did not get the chance to prove whether Stu's forests were home to new species.
But they were indeed, and that's what I found out on May 2009, during a second visit to Stu's lands. This time, I was enthusiastically supported by Catherine Schloegel from Fundación Cordillera Tropical (the NGO that manages the Mazar Reserve) and I was on a mission: to document all of the reptiles and amphibians living on those forests. With this in mind, I revised all of the available literature about the herpetofauna of the southeastern Ecuadorian Andes.
This was a critical step in recognizing whether the found species were potentially new or not. It also was the step that led me towards the investigator Martín Bustamente from Finding Species, whose support and previous work in the Mazar paved the road towards the description of the Bamboo Rain-Peeper. The next step was to get field assistance and to implement surveys among local people; the former, to improve searching success; and the latter, to gather info about rare species or about historical records.
In regard to field assistance, the discovery of Pristimantis bambu would not have been possible without the help and companionship of Jesse Lewis, Seth Adams and all of the enthusiastic people involved in the Round River Conservation Studies programs at the Mazar Reserve during 2009 and 2010. If all expeditions counted with such a fantastic team, discovering all of Ecuador's missing species would be a piece of cake.
Well, being honest, discovering a species new to science is not an easy task, but in the right place, with the right info, and with the right assistance, the task becomes much easier, even fun. For us, it involved staying up until very late while searching for tiny creatures with the aid of a headlamp, or during day, by turning logs over or by raking the leaf-litter. The result was that many seemingly identical frogs appeared during the following days. I grouped all of these under the same species, but later realized some of them sang differently. Moreover, some of them had different markings; pigmentation; and proportions.
Leaving apart the other easily diagnosable species (i.e. those with salient features such as big-size, brilliant colors, horn-like protuberances, marked patterns, etc.) all the little, brownish and inconspicuous toads were initially identified as Mountaineer Rain-Peepers (Pristimantis orestes). I knew though, that frogs grouped based on phenotypic resemblance often are erroneously identified as just one species; a masquerading effect for cryptic diversity.
To elucidate this enigma. I had to gather data and analyze it side by side. First, individual frogs were documented through drawings and photographs; and second, data about ecological preferences, timing, location, and physical traits was obtained for each of the populations.
The data was Raw, but it gave me the hint I needed: those frogs that had a different song also were restricted to only those patches of forest where the bamboo species (Chusquea sp.) was dominant; the other seemingly identical population was instead distributed on old-growth montane forests and paramos. Neither habitats, nor songs overlapped.
I also realized that taking into consideration this speciation pattern (in which two amphibian populations replace one another altitudinally or ecologically) had been the logic behind many other frog discoveries. I therefore concluded that many wide-ranging species (including the Mountaineer Rain-Peeper) were, as a matter of fact, a complex of many more.
But the situation warranted a second opinion. So I came back to Quito, and met Dr. Juan Guayasamin from the Universidad Indoamérica, which in my opinion is Ecuador's ultimate Pristimantis expert. As he has done many times in the past, Dr. Guayasamin, recognized the incipient Bamboo Rain-Peeper as a potentially new species right away, and consequently gave me the advice and support to gather the evidence needed to properly name the new species.
Evidence, in taxonomy terms, means voucher specimens, tissue samples, sound recordings, pictures in life and associated data. Once equipped with the tools (i.e. collecting permits, plastic containers, a sound recorder and many data sheets) to gather the needed evidence, I went back to search for the awaiting new frogs.
There they were, exactly where I left them. Hundreds of Bamboo-Rain Peepers were active that night, making it possible to collect a reasonably diverse sample of individuals, including singing males (for which the calling was recorded), foraging females, perching juveniles, etc. These were going to be the type collection for the Bamboo-Rain Peeper. That is to say, the group of specimens on which the original description of the species was to be based. It was therefore important that the sample was representative; otherwise, different morphological variations and developmental stages could have been confused with another species.
But the above scenario was not a problem because genetic data was taken from each of the voucher specimens. This was done by taking samples from at least three different types of tissues (skin, muscle and liver) per specimen, and storing those in alcohol-filled Eppendorf tubes. Of course, this procedure had to be performed after the frogs were euthanized, and before they were fixed in 10% formaldehyde and stored, each with a specific ID number, in 70% ethanol.
The field phase was over, and the specimens were deposited in the QCAZ museum of herpetology. The lab phase was next.
First, morphological measurements (such as total length, hand length, weight, etc.) were gathered using digital calipers and electronic scales. Second, radiographies were obtained using X-ray generators. Third, data about morphological traits (such as number and disposition of skin protuberances, body shapes and color patterns) was gathered for each of the specimens. The goal was to obtain information to perform a complete cross-species comparison that would support assigning the new frog to the genus Pristimantis, and to prove the validity of the new taxon; essentially by distinguishing it from the other known frogs that belong to the same genus.
The data set was compared to that of other species housed in museum collections and to all the available literature. The Bamboo Rain-Peeper appeared to be undescribed. But this had to be confirmed through a phylogenetic analysis to determine if Pristimantis bambu was indeed genetically different from other closely related frogs, and by comparing the new species' song to that of others. The Bamboo Rain-Peeper was unique in both respects, confirming thus the initial assumption.
Now, it was time to tell the world what both Dr. Guayasamin and I knew, that Ecuador had yet another new frog, and had therefore reached 500 species of amphibians. To do this, however, all of our supporting data had to be published in a scientific journal, which in turn involves writing a fully detailed article explaining methods, a systematic description, natural history, and a discussion justifying the new addition. We also had the honor to name the new frog, following of course the guidelines of the International Code of Zoological Nomenclature. The chosen name was Pristimantis bambu, as an allusion to the new species' preference for bamboo-dominated montane forests (Chusquea sp.).
In May 2011, almost two years after the initial finding, the article has been aproved, revised and published in the prestigious journal Zootaxa, therefore validating the inclusion of Pristimantis bambu in the list of Ecuador's frogs.
A new species has been born! But the race is still on. We, as humanity, need to find what other unknown creatures are still out there so they too, as the Bamboo Rain-Peeper, hold a chance to be saved before it's too late.
Arteaga-Navarro AF and Guayasamin JM (2011) A new frog of the genus Pristimantis (Amphibia: Strabomantidae) from the high Andes of Southeastern Ecuador, discovered using morphological and molecular data. Zootaxa 2876:17–29. PDF
FCT (2008) Nudo del Azuay Conservation Initiative: An Introduction to the Dudas Watershed (Fundación Cordillera Tropical, Cuenca).
Frost DR (2009) Amphibian Species of the World: an Online Reference. Version 5.3. Available at: http://research.amnh.org/herpetology/amphibia/
Hedges SB, Duellman WE and Heinicke P (2008) New world direct-developing frogs (Anura: Terrarana): molecular phylogeny, classification, biogeography, and conservation. Zootaxa 1737.1–182.
Ron SR, Guayasamin JM and Menendez-Guerrero P (In press) in Amphibian Biology, Decline and Conservation, eds Heatwole K and Wilkinson JW (Surrey Beatty & Sons Pty. Ltd., Australia).
Wiens JJ (2004) Speciation and ecology revisited: phylogenetic niche conservatism and the origin of species. Evolution 58:193–197.