Molecular and morphological diversification of a cryptic group of terrestrial frogs in a high-altitude tropical hotspot

Verónica L. Urgiles, University of Central Florida

Pristimantis quintanai, a new species described from the highlands of southern Ecuadorean Andes in collaboration with the rural environmental promotors from the Rio Paute basin. The new species was named after the Mexican herpetologist Pedro Quintana-Ascencio.

Direct-developing frogs in the genus Pristimantis constitute the most diverse genus of terrestrial vertebrates in the world. In the tropical Andes of Ecuador, Pristimantis frogs represent almost 40% of known amphibians. Furthermore, numerous recent species descriptions demonstrate that we have only documented a small percentage of the true diversity within this genus. Species-level taxonomic resolution and diversification in Pristimantis have long been recognized as challenging, mainly because of the presence of complexes of cryptic species. This characteristic is suggested to be a result of repeated environmental selection pressures across similar altitudes, leading to morphological convergence among species. Thus, my project explored the diversity and molecular diversification of a high elevation, and endemic clade of terrestrial frogs from the southern Andes of Ecuador: the Pristimantis orestes species group. 

To achieve this goal, I conducted expeditions and obtained samples from 35 localities across the southern Ecuadorean Andes. I sampled across elevations between 2500 and 4500m, which included type localities of previously described amphibians within the P. orestes group. When possible, I also recorded the calls of male specimens from the sampling localities. Also, while in Ecuador, I visited museum collections to generate morphological comparisons with type material from other Pristimantis species. I extracted DNA and amplified two mitochondrial (12S, 16S) and one nuclear gene (RAG-1) from five specimens for each locality. In total, I generated 480 new sequences. I obtained other available sequences from Pristimantis in GenBank and reconstructed a phylogenetic tree using both maximum likelihood and Bayesian inference. I also generated morphological comparisons for each collected specimen based on other Pristimantis species from Ecuador and Peru. Further, I analyzed and described the recorded calls and create comparisons with available call data from other Pristimantis.

Given that several species within the group were previously described based on morphological data only, I generated the first genetic characterization of these species based on individuals collected from the type localities. Based on the phylogenetic analysis, I recovered 25 strongly supported clades, 18 of which represent undescribed Pristimantis species.

Based on the data collected with this grant, and integrating phylogenetics, genetic distances, morphological comparisons, call data, and geographical data, I have already delimited and described two new species of Pristimantis that I named P. cajanuma and P. quintanai ( Both species are endemic to the montane forest of Ecuador and based on their very restricted distributions (<40km2), we suggested that they should be considered as Near Threatened. I am also in the process of delimiting and describing an additional five new species of Pristimantis. Further, I will be testing hypothesis of diversification within this group using ancestral state reconstruction. 

The support of the Systematics Association was essential to cover the expenses of a field work, in particular funding a field assistant to collect specimens. This funding also supported visits to Ecuadorean Museums, allowing to generate the critical comparisons to type material that were necessary to delimit and describe new species within the P. orestes group.