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Sulcaria isidiifera Brodo

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Scientific name
Sulcaria isidiifera
Common names
splitting yarn lichen
Iron Maiden's Hair
IUCN Specialist Group
Assessment status
Assessment date
IUCN Red List Category
IUCN Red List Criteria
McMullin, T., Allen, J. & Lendemer, J.
Scheidegger, C.

Assessment Notes

The content on this page is fetched from The IUCN Red List of Threatened Species: https://www.iucnredlist.org/species/70386122/70386125


This species is assessed as Critically Endangered (CR) on the basis of it having a very narrow distribution (10 km diameter area), correlating to an extent of occurrence of less than 100 km², and an area of occupancy of just 8 km². A continuing decline in the extent of occurrence, and the number of mature individuals is reported, and it is considered that this species severely fragmented and found in 1-4 locations based on the threats of development and changes to the fire regimes.

Geographic range

This species is narrowly restricted to a small area of old-growth coastal chaparral scrub on stable sand dunes in San Luis Obispo County, California, U.S.A.

Population and Trends

Sulcaria isidiifera was first discovered in 1984 and was formally described in 1986 (Brodo 1986). It is only known to inhabit an area that is 7 miles across at its widest point (Carlberg and Knudsen 2007). Repeated visits in recent years, including a 2012 visit from C. Bratt (one of the original two people that discovered it), documented significant observed decline in the population and habitat fragmentation (C. Bratt pers. comm., Carlberg and Knudsen 2007). Most known occurrences are within three state parks: Montana de Oro State Park, Morro Bay State Park, and Los Osos Oaks State Reserve, with the highest abundance at Montana de Oro (Reifner 1995). The rest of the population is on private or unregulated land (Carlberg and Knudsen 2007).

Population Trend: decreasing

Habitat and Ecology

This is a corticolous species that is restricted to old-growth coastal chaparral scrub (Carlberg and Knudsen 2007). It occurs on the branches of trees and shrubs such as: Adenostoma fasciculatum, Quercus dumosa, Q. agrifolia, and Ceanothus ramulosus (Brodo 1986, Carlberg and Knudsen 2007).


This species is threatened by residential development and changes in fire regimes. Development is the biggest threat to this species. Two communities, Los Osos and Baywood, have grown substantially in the last thirty years since Sulcaria isidiifera was discovered. They are within the range of this species and new development is reducing the already small area of suitable habitat.

Conservation Actions

This species needs to be listed as an endangered species in the United States. Additionally, efforts need to be made to protect populations from residential development. Because of the small population size of this species and significant loss of habitat, reintroduction to areas where it has been lost should be attempted.

Monitoring the abundance and health of this species needs to begin immediately. Also, the viability of reintroduction should be explored.

Source and Citation

McMullin, T., Allen, J. & Lendemer, J. 2019. Sulcaria isidiifera. The IUCN Red List of Threatened Species 2019: e.T70386122A70386125. https://dx.doi.org/10.2305/IUCN.UK.2019-3.RLTS.T70386122A70386125.en .Downloaded on 30 January 2021

Country occurrence