A New Species of Minute Noblella (Anura: Strabomantidae) from Southern Peru: The Smallest Frog of the Andes

We describe a new species of Noblella from the upper Cosñipata Valley in southern Peru (Cusco Region). Specimens were found in the leaf litter of a cloud forest between 3025 and 3190 m elevation. The most distinctive character of the new species is its diminutive size (maximum SVL female 12.4 mm, male 11.1 mm). With an average snout–vent length of 11.4 mm (n = 7) in adult specimens, the new species is the smallest Andean frog, and one of the smallest anurans in the world. The new frog is rare (between 30 and 75 frogs/ ha) and found only in montane scrub and forest habitats near the ecotone with the high-Andean puna grasslands. Although the amphibian fungal infection (Batrachochytrium dendrobatidis) has been recorded in southern Peru, no infections were detected in the new species.

Resumen

Describimos una nueva especie de Noblella de la parte alta del Valle Cosñipata en el sur de Perú (Región Cusco). Los especímenes fueron encontrados en la hojarasca del bosque nublado a elevaciones entre 3025 y 3190 m. La característica más destacada de la nueva especie es su tamaño diminuto (longitud hocico–cloaca máxima 12.4 mm en hembras y 11.1 mm en machos). Con una longitud promedio de 11.4 mm (n = 7) en individuos adultos, esta especie es la ranita más pequeña de los Andes, y entre los anuros más pequeños del mundo. Esta nueva ranita es rara (densidad entre 30 y 75 individuos/ha) y habita los matorrales y bosques nublados cerca del ecotono con los pajonales altoandinos (puna). La infección causada por el hongo Batrachochytrium dendrobatidis ha sido reportada en anuros del sur de Perú; sin embargo no detectamos la presencia de este hongo en individuos de la nueva especie.

Fig. 1

Noblella pygmaea (MUSM 26320, holotype, SVL 12.4 mm) in lateral (A), dorsal (B), and ventral (C) views. Photos by A. Catenazzi.

Fig. 2

Lateral (A) and dorsal (B) views of head and ventral views of hand (C) and foot (D) of Noblella pygmaea (MUSM 26320).

Fig. 3

Type locality (indicated by an arrow) of Noblella pygmaea in southern Peru.

Fig. 4

Elevation profile (right) and estimated density (left; average number of frogs/100 m² + SE) of Noblella pygmaea and sympatric species of Bryophryne and Psychrophrynella between 2800 and 3400 m elevation in the upper Cosñipata Valley, based on 10 × 10 m² quadrat plots during the wet seasons of 1998, 1999, and 2008 and the dry season of 2007 (n = 72).

Fig. 5

Montane forest at the quadrat plot where one specimen of Noblella pygmaea (MUSM 26318) was collected, 250 m east of the type locality, on 1 August 2007. Photo by A. Catenazzi.

Contributor Notes

Associate Editor: D. Kizirian.

¹ Staatliche Naturhistorische Sammlungen Dresden, Museum für Tierkunde, Königsbrücker Landstrasse 159, D-01109 Dresden, Germany; E-mail: edgar.lehr@snsd.smwk.sachsen.de. Send reprint requests to this address.

² Division of Integrative Biology, University of South Florida, 4202 East Fowler Avenue, SCA110 Tampa, Florida 33620. Present address: Department of Integrative Biology, University of California at Berkeley, 3060 Valley Life Sciences Building #3140, Berkeley, California 94720; E-mail: acatenazzi@gmail.com.

Received: 18 Dec 2007

Accepted: 24 Sept 2008