The species belongs to the section Nervosae within the genus Anzia due to the presence of a chondroid axis.
This species occurs only with two small populations on one volcano in the world. It is threatened by accidental extinction by trampling, grazing and possibly collecting.
Criterion A: There are not reports about the trends of population size over long time periods, so it is not possible to apply this criterium.
Criterion B: Both B1 and B2 subcriteria could be applied as the extent of occurrence is smaller than 100 km2 and the area of occupancy is surely smaller than 10 km2. However, the species does not fit the two necessary conditions for this criterium. It only fits B1a (or B2a) as we can consider it occurs in a single population worldwide. However no information is available to apply b) or c) conditions about the population size over time.
Criterion C. No information is available about the total number of individuals of this species. Thus, subcriteria C1 or C2 are not applicable.
Criterion D. The total number of individuals is unknown but the Area Of Occupancy is smaller than 20 km2 and the number of locations is 1 which fits subcriterion D2 (Vulnerable).
Criterion E. No quantitave analyses have been carried out.
The species has been assessed as Vu (D2) until more research on the actual number of individuals and population size is carried out.
The species is known from a single peak -old volcano- Pico do Castello on the small Island of Porto Santo in the Madeira Archipelago (Portugal).
The total populations consists of a few dozen square meters at most.
Population Trend: Uncertain
The species grows on bare volcanic rock, in dry, sun exposed habitat (Haugan 1992).
Trampling by tourists and collecting by lichenologists, possibly also animals grazing.
Currently nor conservation actions has been taken to protect the species neither the area is protected.
Conservation translocation to additional outcrops on the same island and to the main island (Madeira) could be effective measures to increase size and robustness of population.
It would be necessary to assess the actual number of individuals in the area as well as the degree of genetic diversity of the population.
Niche modelling in order to help in the search for additional potential habitats in the vecinity of the known population and on the main island (Madeira).
Haugan, R 1992: Anzia centrifuga, a new lichen species from Porto Santo, Madeira. - Mycotaxon 44(1): 45-50