This species is currently known only from three locations, all within the mountains of the Groot Winterhoek Wilderness Area, Western Cape Province, South Africa. It has been recorded at elevations ranging 900–1,100 m asl. It is unlikely that this species occurs outside of the reserve (A. Turner pers. comm. August 2016). The known extent of occurrence (EOO) is about 7 km2 and its area of occupancy (AOO) is 0.06 km2.
Habitat and Ecology
This species is known from thickly vegetated seeps dominated by restioid vegetation, on gentle mountain slopes within montane fynbos. It depends on primarily wet habitats. It breeds by direct development, laying between 6–12 eggs annually (A. Turner, pers. comm. in Dawood and Stam 2006).
One of the three known subpopulations is monitored twice a year. This is the second largest of the three subpopulations and the largest number of calling males is estimated to be less than 50 individuals. Fire and post-fire impacts on number of mature individuals are expected to cause large fluctuations (approximately a five-fold change in abundance at the monitored site; A. Turner pers. comm. 2009) in subpopulation sizes, and the species as a whole is threatened due to the small number of locations. The fluctuations experienced by this species are so far are below the typically used 10-fold increase or decrease (IUCN 2001); however, a five-fold reduction in population size has been observed on two occasions, and it is expected that fires have the potential to reduce subpopulations by a factor of ten or more depending on the severity and timing of the fire.
The best suitable seeps within Groot Winterhoek Wilderness Area (25-30% of all seeps) have been surveyed. One possible location outside of this reserve might have this species, but it is inaccessible and not yet explored (A. Turner pers. comm. August 2016). There is limited suitable habitat outside of the reserve, notably to the immediate north, west and east (it needs montane seeps), and further south other members of the genus occupy suitable habitat. So it is likely to be confined to the Reserve.
The main threat to this species is damage to its habitat, which is primarily threatened by excessively short fire-return intervals and invasion by alien plants. Although the area currently has low densities of alien plant species and an acceptable fire-return interval, these are ever-present and ongoing threats. The invasion of alien invasive woody vegetation increases the impact of fires, which may lead to more dramatic population fluctuations. An additional threat to this species is the proximity of one subpopulation to human residences which may result in water contamination. Active management is required in order to prevent threats escalating.
Most of the known range of this species falls within a protected area: the Groot Winterhoek Wilderness Area. A monitoring programme has been set up to monitor the population near human habitation.
Active management is required, especially with regard to alien invading plants.
Perceived threats and the effects of fire on this and other species in the genus requires research. More research is required on life history and dispersal of this species.
Red List Status
Critically Endangered (CR)
This species is listed as Critically Endangered because its extent of occurrence (EOO) is 7 km2, its area of occupancy (AOO) is 0.06 km2, it is known from only three locations, combined with extreme fluctuations in the number of adult individuals, and a continuing decline in the area and quality of its habitat due to fire and post-fire impacts. Habitat degradation, as alien plant invasion increases the frequency and impact of fires, may lead to more dramatic population fluctuations.
IUCN SSC Amphibian Specialist Group & South African Frog Re-assessment Group (SA-FRoG) 2016. Arthroleptella subvoce. The IUCN Red List of Threatened Species 2016: e.T61860A77161647. http://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T61860A77161647.en .Downloaded on 16 December 2018