This species is known from Laguna de Puruanta on the western slopes of the Cordillera de Pimampiro, Provincia Imbabura, and the vicinity of Laguna de San Marcos, on the border between Provincia Pichincha and Provincia Sucumbíos, Ecuador, between 3,000-3,500 m asl (Gluesenkamp and Guayasamin 2008). Both lakes are separated by about 6 km which consist of disturbed and fragmented habitat (Gluesenkamp and Guayasamin 2008). Despite intense (but time-limited) survey efforts, only a handful of specimens have been collected at the known and surrounding areas (A. Gluesenkamp pers. comm. November 2012). Each site is thus considered to be one threat-defined location. Taking its range as a proxy for extent o occurrence (EOO), this is calculated at 88 km2. However, within this EOO, the species' range is limited by elevation and presence of undisturbed habitat.
Habitat and Ecology
It is a nocturnal species occurring in high elevation tropical forests, either associated with epiphytic bromeliads or on the ground, often under logs or at the base of plants of the family Poaceae (Gluesenkamp and Guayasamin 2008). Typical habitats are dense forest patches dominated by Miconia trees, which are covered with a variety of epiphytic plants including ferns, orchids and mosses (Gluesenkamp and Guayasamin 2008). Females lay between 35 and 50 eggs which are presumed to be laid in terrestrial habitats and to undergo direct development, as with other congeners (Ruiz-Carranza and Hernández-Camacho 1976).Given that this species has only been found in very few sites, all undisturbed by human impact, it is probable that it would not tolerate plantations or other disturbance e.g. roadside clearing (A. Glusenkamp pers. comm. March 2013). In addition, very few individuals of any Osornophryne species have been found in roadside habitat or other disturbed areas and none have been found in plantations or agricultural plots of any kind (A. Glusenkamp pers. comm. March 2013). This also suggests that this species is not tolerant of habitat disturbance and human modified habitats.
It is known from the type series, comprised of eight specimens, all adult females (Gluesenkamp and Guayasamin 2008). No males of this species have been found.
It is threatened due to dam construction at Laguna de San Marcos (A. Gluesenkamp and J. Guayasamin pers. comms. November 2012). This is resulting in a loss of forest due to clearance for road access (A. Glusenkamp pers. comm. March 2013). Gluesenkamp and Guayasamin (2008) also indicate further ongoing habitat loss and fragmentation at both sites where this species has been found. Fires have been recorded as a threat for an endemic plant Centropogon cazaletii at Laguna de San Marcos (Moreno and Pitman 2003) and are presumed to also be a threat to this amphibian since it requires vegetation for reproduction. Therefore a combination of forest loss due to human clearance and increasing fires are likely to constitute the greatest threats to this species (A. Glusenkamp pers. comm. March 2013).
Laguna de San Marcos is located within the Reserva Ecológica Cayambe Coca (Moreno and Pitman 2003) but there are no specific projects to protect this species (A. Glusenkamp and J. Guayasamin pers. comms. November 2012). Specific protection of habitats within the vicinity of the dam construction is required. In addition, further surveys are needed to determine the population status and ecology of this species.
Red List Status
Listed as Endangered given that it has an estimated extent of occurrence (EOO) of 88 km2, it is considered to occur in two threat-defined locations, and there is ongoing decline in the quality of its habitat in northern Ecuador.
IUCN SSC Amphibian Specialist Group 2013. Osornophryne puruanta. The IUCN Red List of Threatened Species 2013: e.T18435557A18629766. http://dx.doi.org/10.2305/IUCN.UK.2013-1.RLTS.T18435557A18629766.en