Glassfrogs, Centrolenidae, are a charismatic group of Neotropical Treefrogs distinguished by the transparent skin on their undersides, generally combined with a leaf-green dorsal surface. These Frogs lay their eggs in out-of-water environments close to streams, and have forward directed eyes. The males often have spines on their humeri. The Family Centrolenidae takes its name from the genus Centrolene, the third most species-rich genus in the group, currently containing 24 confirmed species and six possible ones. The genus has been well studied genetically, with DNA sequences available for 21 of the 24 confirmed species. Sixty three species of Glassfrogs, from ten genera, have been described from Ecuador to date, including 12 species of Centrolene, with DNA sequences available for 11 of these.
In a paper published in the journal ZooKeys on 22 February 2023, Paul Székely of the Museo de Zoología and the Laboratorio de Ecología Tropical y Servicios Ecosistémicos at the Universidad Técnica Particular deLoja, and the Research Center of the Department of Natural Sciences at Ovidius University Constanţa, María Córdova-Díaz, Daniel Hualpa-Vega, and Santiago Hualpa-Vega, also of the Museo de Zoología at the Universidad Técnica Particular de Loja, and of the Fundación Green Jewel, and Diana Székely, again of the Museo de Zoología and the Laboratorio de Ecología Tropical y Servicios Ecosistémicos at the Universidad Técnica Particular de Loja, and the Research Center of the Department of Natural Sciences at Ovidius University Constanţa, describe a new species of Centrolene from the Refugio de Vida Silvestre El Zarza in Zamora Chinchipe Province, southern Ecuador.
The new species is named Centrolene zarza, in reference to the Refugio de Vida Silvestre El Zarza, a nature reserve founded in 2006, in order to protect the Cordillera del Cóndor’s biological richness, with a particular emphasis on its Amphibians and the Amazonian Tapir; the reserve is home to more than 50 species of Amphibians, as well as the Amazonian Tapirs, and other distinctive Mammal species, such as Jaguars, Oncilla (Spectacled Bears), and countless species of Plants and Birds. The species is described from two female and five male specimens, all collected within the reserve.
Centrolene zarza is a medium-sized Glassfrog, with the holotype female measuring 25.5 mm from snout to vent and weighing 1.05 g. The dorsal surface of the species is light green, being slightly darker above the head and arms, The flanks are white or transparent, the underside transparent. The bones, visible through the skin, are green, other internal organs white or yellowish. The head is slightly narrower than the body, but still wider than it is long. The snout is rounded, with slightly elevated nostrils. The eyes are moderately sized, with a diameter 34% of the head length, the iris is yellow with thick and thin black reticulations. Some warts are present on the dorsal surface, these are elevated, sometimes enameled, and marked by white spots. The limbs are slender.
Two clutches of eggs were observed, both laid on the upper side of leaves, about 3 m above a stream. These clutches contain 13 and 33 eggs respectively, and were apparently not tended by adults. Székely et al. were able to hatch the eggs in the laboratory, but not raise them as far as metamorphosis.
Centrolene zarza was found only in the vegetation bordering two small streams within the Refugio de Vida Silvestre El Zarza, although within this limited range it was apparently quite abundant, being seen or heard on 50% of occasions when the site was visited, typically on the upper side of leaves. Males were heard calling in January, March, June, October, and November, although they were distinctly more active in March and October. No direct interactions between Frogs were observed.
Given this very limited distribution, less than 7 km ², Székely et al. recommend that Centrolene zarza be treated as being Critically Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species. They further note, that while the species entire known distribution is within a protected area, that area is now surrounded by mining concessions, with mining reaching the northern boundaries of the reserve and signs of illegal mining within the reserve, particularly along the banks of streams.
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