Addendum to post
This is a revised edition of the original post. This revision includes corrections and information gained during correspondence with the preeminent herpetologist Dr. Philippe Kok, who was kind enough to point out a few errors and necessary additions.
First, the errors.
1) Our specimen of O. cryptica was not the first record of the genus Oreophrynella found at a talus slope. O. macconneli (a different species of Oreophrynella not found on Auyan) has been recorded as low as 800 meters in Guiana.
2) The distribution we found for this animal, while different from that found by the Terramar-Goelet Museum expedition, is not entirely unusual, as it is in the same altitudinal band (approx 1700 meters) as the original specimens.
Now, the additions.
1) It would seem that O. cryptica prefers the type of habitat we found our specimen in at Penon- forested we areas as oppose to dry rocky areas that O. quelchii is found in on Roraima.
2) It is very probable that O. cryptica is common on Auyan, but the habitat that it is found in makes this frog difficult to spot. It mostly prefers wet mossy areas, and spends its time in leaf litter. 3) This species seems to be present in greater concentration near the Libertador area. It was heard by Dr. Kok a few kilometers northeast of Libert
ador, and also seen there by Adrian Warren. It would be interesting to see how the population density of this animal varies on Auyan with altitude and vegetation.
Plan of action
This new information has made it possible to formulate an addition to the Tepui Watch 2014 plan. Specifically, we will be looking for O. cryptica in similar vegetational assemblages as those of the talus slope areas, and attempt to conduct a population density analysis. We will also focus or efforts to finding additional specimens of this rare endemic frog in the Libertador area.
Oreophrynella found near Penon
As I previously posted, Biokryptos has been conducting our latest and most ambitious project to date: Tepui Watch 2014. This is a camera trapping transect survey which follows the "Laime Trail", a path from campo Guayaraca to the northern lagoons and finally terminates in the Valle Encantado in the western portion of Auyan Tepui. The project has three phases: talus slope surveying, trail surveying, and finally camera trapping in unexplored regions of Auyan.
At this time, we have concluded the talus slope survey of the southern portion of Auyan, having spent some five months in and around campo Guayaraca and Penon, at 1000 meters and 1500 meters respectively. The talus slopes of Auyan represent an under surveyed periphery of this tepui- some 200 square kilometers of pristine forests and complex transitional vegetation. This is due to the fact that the majority of previous exploration has been focused on the summit environments of Auyan, and the talus slopes are difficult to transverse and survey. However, with the realities of global climate change we can no longer ignore this transitional vegetation zone, as it is currently in a state flux due to vertical displacement of flora driven by climate change. The talus slopes can tell us how the flora and fauna of Auyan will change in the future, so long as we maintain continual surveillance of this area.
As our camera trap team collected the data from the traps at Penon and moved them up to the next target area, the labyrinth structure and forests around the El Oso formation on the summit, they conducted a transect survey of the talus slopes from 1500 to 2200 meters. Between Penon and Libertador (the first summit camp), they made a startling discovery....they found and recorded the presence of an extremely rare species of frog, the highly endemic and enigmatic Oreophrynella cryptica.
|Oreophrynella cryptica, found between camp Penon and the summit of Auyan Tepui|
Diagnosis and history of Oreophrynella cryptica
This small species of frog was first mentioned on Auyan in 1959 under the name O. quelchii, then collected in 1974 by the late Adrian Warren in temporary pools near campo Libertador, at 2400 south of campo Naranja. The species O. cryptica was first described by Senaris ( Senaris, J. C. Una nueva especie de Oreophrynella (Anura; Bufonidae) de la cima del Auyan-tepui, Estado Bolivar, Venezuela. Memoria de Sociedad de Ciencas Naturales La Salle 53(140): 177-183) from two female specimens found at the eastern section of the Auyan Tepui massif. The Biokryptos specimen was found far from the collection point of Senaris, in between Campo Penon (1838 meters) and Libertador (2400 meters), in the southern access point of the "Laime trail" on Auyan Tepui.
O. cryptica differs from other species of Oreophrynella in that they posses large cranial crests, and have smaller, smoother, less dense skin tubercles. They are morphologically similar to O. huberi from Cerro El Sol ( an isolate to the north of Auyan Tepui), with a different coloration than O. huberi which is a rufous orange. The specimen of O. cryptica which serves as the holotype is a dark reddish brown dorsally, with a yellow/orange conspicuous lateral stripe. The entire ventral portion of O. cryptica is yellow/orange as well. Our specimen of O. cryptica seems to lack this lateral stripe and the ventral portion is yellow/green, which is unusual and requires further analysis.
The genus Oreophrynella is fascinating to study from a natural history standpoint, as it seems highly endemic to the point that all species are considered single tepui endemics with the exception of O. nigra which has been found on Kukenan and Yuruani Tepuis. While originally considered a species derived from the in situ evolution of a paleofaunal ancestor, recent molecular phylogenetic analysis indicates that the populations of Oreophrynella are recently speciated during the Pleistocene. This supports the hypothesis the the various species of Oreophrynella maintained contact through temperature and ecosystem corridors during the Pleistocene, when tepui ecosystems were some 500 meters lower in elevation than they are today.
However, our find seems to change some of these notions, as this specimen was found in a non-summit ecosystem for the first time approximately 1700 meters (While this is true for O. cryptica, other species of Oreophrynella have been found at lower altitudes. See the addendum at the beginning of the post for further details). Our specimen was found in talus slope forest, which while rocky is floristically diverse.
On a note of some relevance to the operation of Biokryptos, I would like to state that this discovery supports the notion that the most qualified field observers are the indigenous Pemon people, who are familiar with their territory and its natural history. This discovery could not have been made without Biokryptos member and primary camera trapping operator Arturo Berti, who made this discovery. His diligence, expertise and professionalism has made this project possible. I would also like to thank Alberto Pomares and Vittorio Assandria, who have organized all the technical elements of this project, and continually work to improve our processes.