Friday, March 24, 2017

[Herpetology • 2017] Pristimantis ecuadorensis • Diversification of the Rainfrog Pristimantis ornatissimus in the Lowlands and Andean Foothills of Ecuador

 Pristimantis ecuadorensis
Guayasamin, Hutter, Tapia, Culebras, Peñafiel, Pyron, Morochz, Funk & Arteaga, 2017 


Geographic barriers and elevational gradients have long been recognized as important in species diversification. Here, we illustrate an example where both mechanisms have shaped the genetic structure of the Neotropical rainfrog, Pristimantis ornatissimus, which has also resulted in speciation. This species was thought to be a single evolutionary lineage distributed throughout the Ecuadorian Chocó and the adjacent foothills of the Andes. Based on recent sampling of P. ornatissimus sensu lato, we provide molecular and morphological evidence that support the validity of a new species, which we name Pristimantis ecuadorensis sp. nov. The sister species are elevational replacements of each other; the distribution of Pristimantis ornatissimus sensu stricto is limited to the Ecuadorian Chocó ecoregion (< 1100 m), whereas the new species has only been found at Andean localities between 1450–1480 m. Given the results of the Multiple Matrix Regression with Randomization analysis, the genetic difference between P. ecuadorensis and P. ornatissimus is not explained by geographic distance nor environment, although environmental variables at a finer scale need to be tested. Therefore this speciation event might be the byproduct of stochastic historic extinction of connected populations or biogeographic events caused by barriers to dispersal such as rivers. Within P. ornatissimus sensu stricto, morphological patterns and genetic structure seem to be related to geographic isolation (e.g., rivers). Finally, we provide an updated phylogeny for the genus, including the new species, as well as other Ecuadorian Pristimantis.


Pristimantis ecuadorensis sp. nov. Guayasamin, Hutter, Tapia, Culebras, Peñafiel, Pyron, Morochz, Funk, Arteaga.
Eleutherodactylus ornatissimus Lynch & Duellman 1997, in part.
Pristimantis ornatissimus Arteaga, Bustamante & Guayasamin 2013, in part.

Suggested common name in English: Ecuadorian Rainfrog
Suggested common name in Spanish: Cutín de Ecuador

Diagnosis: Pristimantis ecuadorensis is characterized by the following combination of characters: (1) skin on dorsum shagreen, that on venter smooth; discoidal fold defined posteriorly, (2) tympanic membrane and tympanic annulus evident, oval, (3) snout long, acuminate in dorsal view, rounded in profile, (4) upper eyelid lacking tubercles, (5) dentigerous process of the vomer present, bearing teeth, (6) males having vocal slits and Type I nuptial pads, (7) first finger shorter than second, (8) fingers with lateral fringes, (9) ulnar tubercles absent, (10) heel and tarsus lacking tubercles or folds, (11) inner metatarsal tubercle oval, 4–5x round outer metatarsal tubercle, (12) toes bearing lateral fringes; webbing absent; discs large; fifth toe much longer than third, (13) in life, greenish yellow dorsum with transversal black stripes that may form a reticulated pattern; iris light blue to grayish green or grayish yellow; in preservative, dorsum cream with black stripes, and (14) SVL in adult males 25.4 mm (n = 1) and 37.1–40.2 in adult females (n = 2).

Distribution: Pristimantis ecuadorensis is known only from three nearby localities on the western slopes of the Ecuadorian Andes, provinces of Cotopaxi and Pichincha, at elevations between 1450–1480 m. The localities are: 3 km NE of San Francisco de Las Pampas, Palo Quemado, and Tandapi. With the information at hand, the distribution of P. ornatissimus sensu stricto is constrained to the Chocoan lowlands and Pacific Andean foothills (< 1100 m) of Ecuador. 

Natural History: Information for Pristimantis ecuadorensis is mainly available from the type locality (Fig 8), San Francisco de Las Pampas, a forested valley along the Río Toachi, located at 1480 m in the northwestern slopes of the Ecuadorian Andes. The locality has a mean annual precipitation of 2325 mm. In this area, P. ecuadorensis is found in primary forest and closely associated with the leaf axils of bromeliads, Heliconia plants and palm fronds (genera Ceroxylon and Wettinia) (field notes of Giovanni Onore, César Tapia, and W. E. Duellman). Additionally, the species is associated with banana (Musa paradisiaca) and sugar cane plantations (Saccharum officinarum) bordering native forest (Fig 9). In these ecosystems, P. ecuadorensis perch on top of leaves or inside leaf axils (~15–150 cm above the ground), creased leaves or moss of epiphytic plants, and have been heard calling from them. Additionally, by inspecting fecal samples, we found the remains of beetles, crickets and spiders. In captivity, females of P. ecuadorensis reach sexual maturity after 14 months, and males start vocalizing after 10 months.

Etymology: The specific name ecuadorensis refers to the Republic of Ecuador, where the species is endemic. The name is intended to highlight the overwhelming beauty, and cultural and biological diversity of Ecuador.

Fig 1. Color variation in sequenced Pristimantis ornatissimus sensu stricto and Pristimantis ecuadorensis sp. nov. in Ecuador.


Juan M. Guayasamin, Carl R. Hutter, Elicio E. Tapia, Jaime Culebras, Nicolás Peñafiel, R. Alexander Pyron, Carlos Morochz, W. Chris Funk and Alejandro Arteaga. 2017. Diversification of the Rainfrog Pristimantis ornatissimus in the Lowlands and Andean Foothills of Ecuador. PLoS ONE. 12(3): e0172615. DOI: 1371/journal.pone.0172615

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