Assessment Notes

Justification

This is a Macaronesian endemic, only known worldwide from Porto Santo Island. This species is not currently protected and is at high risk of extinction. There are under 100 individuals, which meets the criterion D threshold for Endangered of under 250 mature individuals. Although this species has a restricted distribution and occurs in a single subpopulation, there is no information on continuing declines and therefore, this species cannot be assessed under criteria B or C. Therefore, this species is assessed as Endangered.

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Taxonomic notes

This species is morphologically different from all other Ramalina species in Macaronesia (Aptroot and Schumm 2008) and elsewhere in the world. See Aptroot and Schumm (2008) for a key to distinguish this species from others.

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Geographic range

This is a Macaronesian endemic and is only known worldwide from Porto Santo Island. It was described in 1990 and has never been found anywhere else, but is always observed by lichenologist visiting the only locality.

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Population and Trends

The area of occupied habitat of the population is certainly less than 100 m². This species occurs on several volcanoes, but only at higher altitude (above 200 m asl), and it is only known from Porto Santo. The extent of occurrence (EOO) is c. 10 km².

In May 2015, an attempt was made to assess the total number of individuals of this species. About 100 individuals were found in four different localities (Aptroot pers. comm.). The species was never present in large groups, but mixed in between other, locally more common Ramalina species. However, only 10% of the suitable habitat could be investigated as much of it is on steep rock surfaces.

Population Trend: stable

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Habitat and Ecology

This species is found on exposed rock faces of old volcanoes. It is always scattered between other, dominant, Ramalina species.

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Threats

The threats to this species are trampling by tourists who go off the tracks and collecting by lichenologists.

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Conservation Actions

Tourism to the summit of the Pico de Facho should be strictly regulated, either by forbidding access altogether (which will impossible to control) or rather by opening a small trail and putting an information shield in place alerting the tourist on the unique lichens present, and the harm done to them by trampling. This species should feature on a leaflet with protected plants.

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Use and Trade

This species is not utilised.

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Source and Citation

Aptroot, A. 2015. Ramalina erosa. The IUCN Red List of Threatened Species 2015: e.T70382699A70382708. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T70382699A70382708.en .Accessed on 3 February 2024

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• Country occurrence