This species is known only from the southern slopes of Mount Manengouba at 1,750-2,000 m asl in western Cameroon. As the area is well sampled and well known (research has been ongoing there from 2005-2011), and the species is a habitat specialist and is increasingly surrounded by unsuitable habitat, it is appropriate to use the known range as a proxy for its estimated area of occupancy (AOO) of 15 km2. The estimated extent of occurrence (EOO) can be considered as equal to the AOO for the same reasons.
Amiet in Gartshore (1986) predicted that the species would be found in the Rumpi Hills and even Nigeria, but in the 26 years since the publication of that prediction no record has been signalled (N. Gonwouo pers. comm. 2012). However, the Rumpi Hills, a site relatively close to Mount Manengouba which has relatively similar intact forest, has not been well investigated in recent years (N. Gonwouo pers. comm. 2012). Thus it is unknown whether the species is likely to occur more widely.
Habitat and Ecology
The species has been found in and around a small stream running through dense secondary bush and montane forest; it has not been recorded from primary forest because this habitat has been destroyed. It hides under large rocks and small stones, and presumably breeds in streams.The extent and quality of its forest habitat on Mount Manengouba is declining.
No quantitative population status information is currently available for this species. However, despite visits to all known sites in 2011 and 2012, the last sighting was in 2010 and it was last heard calling in August 2012. As with other amphibian species on Mount Manengouba, it has been seen and heard less frequently over the years, causing experts to believe it is disappearing. While the cause of this population decline is currently unknown, it may be related to ongoing declines in habitat and increasing human pressure on its remaining habitat, but it is not thought to be natural fluctuation (M. Hirschfeld pers. comm. 2012).
The major threat is increasing habitat loss as a result of agricultural encroachment, including plantations of tree crops, expanding human settlements, and removal of wood by local people for firewood and building materials.
On Mount Manengouba, trampling by livestock in the forest is a threat to this species and degrades its habitat. The use of herbicides and pesticides here is suspected to have long-term effects on the stream habitat, affecting the larval stage, and this threat is expected to increase as human activity in the area increases (N. Gonwouo pers. comm. 2012). Deforestation on Mount Manengouba also occurs due to the unsustainable collection of bark from Prunus africanus, a high-elevation tree endemic to the Cameroon highlands, by the method of tree ringing. The tree's bark is used in small amounts for medicinal purposes by local people. However, it is also sold to pharmaceutical companies in large amounts, in which case all the bark is removed from the individual trees, resulting in their death. The consequence of the latter practice changes the microclimate required for the species' survival (Gonwouo pers. comm. 2012). Furthermore, as with other high-elevation species, the species' habitat may be affected by climate change (Gonwouo pers. comm. 2012), although this necessitates further research.
It does not occur in any protected areas. The protected area network in western Cameroon urgently needs to be expanded to include the remaining montane forest habitats, particularly those on Mount Manengouba, which has been proposed as a protected area (N. Gonwouo pers. comm. 2012). On Mount Manengouba, the harvesting of Prunus africanus should be sustainably managed, including education of the local people (N. Gonwouo pers. comm. 2012). There is a need for further survey work to determine the species' current population status, life history and ecology, and the potential impact of climate change.
Red List Status
Critically Endangered (CR)
This species is listed as Critically Endangered (CR) because its estimated area of occupancy (AOO) and extent of occurrence (EOO) are 15 km2, which narrowly misses the CR threshold for AOO but is well within the limits for EOO. This could be a miscalculation and, due to unbridled habitat loss, could drop rapidly in the near future. The EOO is equal to the AOO as the species is a habitat specialist surrounded by unsuitable habitat in a well-sampled area. It is restricted to only one threat-defined location, and the extent and quality of its forest habitat on Mount Manengouba is declining, completely lacking protection on any level.
IUCN SSC Amphibian Specialist Group 2014. Cardioglossa trifasciata. The IUCN Red List of Threatened Species 2014: e.T54410A16866334. http://dx.doi.org/10.2305/IUCN.UK.2014-3.RLTS.T54410A16866334.en .Downloaded on 16 January 2019