New Species of Marsupial Frog (Hemiphractidae: Gastrotheca) from an Isolated Montane Forest in Southern Peru

Abstract

We describe a new species of marsupial frog (genus Gastrotheca) from an isolated patch of cloud forest in the upper reaches of the Pachachaca River, a tributary of the Apuro ´mac River in southern Peru (Apuro ´mac Region). The new species is small with males less than 30 mm and a single female 35.3 mm in snout-vent length. A juvenile was collected from inside an epiphytic bromeliad at ,3 m, suggesting that this species is arboreal or uses bromeliad tanks as microhabitats. We describe the advertisement call, which has a dominant frequency above 2.2 kHz. Based on morphology and advertisement call, the new species is most similar to Gastrotheca piperata described from the Yungas of Bolivia. The new species differs from G. piperata by having smaller size, no dermal fold on the tarsus, a bluntly rounded to vertical snout in profile, gray coloration on dorsal surfaces of Fingers I and II and by producing advertisement calls that have a higher dominant frequency and a smaller number of pulses. RESUMEN.—Describimos una nueva especie de rana marsupial (genero Gastrotheca) de un parche aislado de bosque nublado en las nacientes del ro ´o Pachachaca, un afluente del ro ´o Apuro ´mac en el sur de Peru ´ (Region Apuro ´mac). La nueva especie es pequena, con machos que miden menos de 30 mm y una hembra 35.3 mm en longitud hocico-cloaca. Un juvenil fue capturado dentro de una bromelia epo ´fita a una altura de ,3 m, lo cual sugiere que esta rana es arborea o usa las bromelias como microhabitats. Describimos el canto nupcial, cuya frecuencia dominante es de mas de 2.2 kHz. En base a morfologo ´a y canto nupcial, la nueva especie se asemeja masa Gastrotheca piperata descrita de las Yungas de Bolivia. La nueva especie se diferencia de G. piperata por su menor tamano, ausencia de pliegue tarsal, hocico redondeado o vertical en vista lateral, coloracion gris en la superfice dorsal de los dedos I y II y por producir un canto nupcial con frecuencia dominante mas alta y menor numero de pulsos. Biological inventories and phylogenetic and taxonomic research in the cloud forests of southeastern Peru over the past decade have led to the description of many new species of amphibians (Lehr and Catenazzi, 2008, 2009a,b). These recent discoveries point to the exceptional diversity of montane and high-elevation taxa in the eastern slopes of the Andes. Beta diversity of montane taxa is likely to be much higher than currently known, and as new inventories are conducted, we predict that many additional species will be discovered. These discoveries will help us better understand patterns of species abundance and distribution in relation to the heterogeneous environment of the eastern cordilleras and inter-Andean valleys of southern Peru. The herpetofauna of the Apurimac region is poorly known. The west and central portions of this region are dominated by species that have a wide geographic distribution in the puna and other high-elevation habitats of the Peruvian Altiplano, such as Gastrotheca marsupiata, Pleurodema marmoratum, and Tachymenis peruviana. However, the eastern portion of the Apurimac Region has more species, several of which are endemic. The inter-Andean dry valleys of the Apurimac canyon and of its tributaries, for example, are inhabited by two endemic squamates, the lizard Stenocercus apurimacus and the snake Drymoluber apurimancesis (Lehr et al., 2004). These valleys often present heterogeneous environments, from dry, scrublike vegetation in places where the cordilleras function as rain shadows, to cloud forests where local topography intercepts moisture and favors the formation of fog. Many of these habitats are difficult to access and are poorly known biologically. Based on museum collections, G. marsupiata is the only marsupial frog that has been reported previously from Apurimac. William E. Duellman collected a series of this species in four locations between Abancay and Huancavelica (voucher specimens at the Museum of Natural History,