Rationale
Prostalia granulata is assessed as Endangered (EN). It is found along the east coast of South Africa, where its distribution is estimated based on only three fairly widely spaced locations, with an estimated area of occurrence (AOO) of no more than 20 km² and a severely fragmented population. A continuing decline in the number of mature individuals is inferred based on only a handful of specimens existing in museum collections as well as no recorded sightings of the species for over three decades. The extent and quality of the habitat of the species are also inferred to be declining based on land use change due to agriculture and urban development, and the spread of invasive alien vegetation.
Distribution
Prostalia granulata is endemic to South Africa, where it is found along the east coast. The species is only known from three locations. Its extent of occurrence (EOO) is ca 62,000 km², but the area of occupancy (AOO) is just 12 km² with an upper estimate of 20 km².
Population trend
Trend
The population size and trend of this species is unknown. The subpopulations are very small and isolated with probably no exchange between them. The population is therefore considered severely fragmented as these small subpopulations are likely to be non-viable. The species is very rarely encountered in the field and has not been collected for 38 years, despite the geographic area where the species is recorded to occur being fairly well surveyed. Therefore, a continuing decline in the number of mature individuals is inferred.