This species is known only from the Kosñipata Valley (1,400–1,900 m asl), Cusco Region, in the eastern slopes of the Andes in southern Peru. Similar valleys have been surveyed elsewhere in southern Peru, but the species has not been found outside the vicinity of its type locality (A. Catenazzi pers. comm. May 2014).
Habitat and Ecology
Its habitat is tall primary and secondary Amazonian cloud forest with some tree ferns and bromeliads and luxuriant undergrowth of mosses and ferns. In the past, individuals have been recorded perched on and calling from the upper sides of ferns along a dripping cliff at night (this species is often found close to streams and waterfalls). Eggs are deposited on leaves and the larvae develop in streams.
It was once frequent in small streams and near waterfalls, especially at elevations between 1,600–1,800 m asl at the type locality (A. Catenazzi pers. comm. May 2014). It has disappeared from all streams it occupied at the type locality in the Kosñipata Valley in the period from 2000 to 2006. Preliminary data indicate the arrival of Batrachochytrium dendrobatidis to this region between 2000 and 2007 (A. Catenazzi unpublished data). It has not been seen since 2005, despite intensive and targeted surveys at known occupied streams in 2008, 2009, and each year during 2012–2017 (A. Catenazzi pers. comm. April 2017), suggesting that this species may be possibly extinct. If it is still extant, the population size would likely be less than 50 mature individuals (A. Catenazzi pers. comm. May 2014).
It used to be frequent in small streams and waterfalls where it could be observed throughout the year, and where it was especially abundant during the peak of the rainy season (December-March; A. Catenazzi pers. comm. May 2014). Many sympatric, stream-breeding anuran species have disappeared during the same period (Catenazzi et al. 2011). As Batrachochytrium dendrobatidis was first reported from Cusco in 2002, and given that an epizootic episode occurred in the period from 2000 to 2006, it is thought to be implicated in the population decline and possible extinction of this species (A. Catenazzi pers. comm. May 2014).
Its range is contained within Parque Nacional Manu and its buffer zone in the Kosñipata Valley, Cusco Region, Peru.
Should it still be extant, ex situ and species recovery considerations are recommended for this species.
Given its disappearance from its only known locality, surveys in nearby suitable habitat are urgently needed to determine if the species is still extant.
Red List Status
Critically Endangered (CR)
Listed as Critically Endangered in view of the relatively recent (2000–2005) collapse of its entire known population in the buffer zone of a well protected national park in southeastern Peru, possibly involving chytridiomycosis, which has been confirmed in the area. Should the species still be extant, it is likely that it survives in low numbers, possibly less than 50 mature individuals.
IUCN SSC Amphibian Specialist Group 2017. Nymphargus truebae. The IUCN Red List of Threatened Species 2017: e.T54999A60338909. http://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T54999A60338909.en .Downloaded on 18 January 2019