• 1Proposed
  • 2Under Assessment
  • 3Preliminary Assessed
  • 4Assessed
  • 5Published

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
Proposed by
Jessica Allen
Sergio Perez-Ortega, Toby Spribille
Jessica Allen, Troy McMullin
Comments etc.
André Aptroot, Anders Dahlberg, Christoph Scheidegger

Assessment Notes

Taxonomic notes

From Brodo (1986):Thallus dull yellowishwhite
grading into light brown and reddish-brown at
the more exposed tips; rarely shades of olive-gray in
places ... 3-5 cm long; main branching isotomic to
anisotomic-dichotomous, with more-or-less
perpendicular spinulose branches developing from
splits in the thallus; branches splitting lengthwise and
opening into rather wide linear soralia filled with
spinulose isidia and spinules, often with brown tips;
main branches 0.3 - 0.5mm wide ... very brittle ... .
Apothecia and pycnidia not seen.

Why suggested for a Global Red List Assessment?

This species has a very narrow distribution (12 km diameter area) and is threatened by development and changes in fire regimes.
Criterion A: It does not apply due to the lack of monitoring data.
Criterion B:
    B1: The extent of occurrence in less than 100 km2
    B2: The area of occupancy is less than 10 km2 (Geocat calculates 8 km2).
      a) There exist a single location that is severely fragmented due to development. Two communities (Los Osos and Baywood have grown considerably during the last 30 years) (Carlberg & Knudsen 2007)
      b) Due to recent development a continuous decline is estimated for 1) extent of occurence, ii) area of occupancy, iii) quality of habitat

C) Criterion C does not apply as no information about number of thalli (or number of trees occupied) is available.

D) Criterion D does not apply as number of mature individuals is not known.
Criterion D2 apply for Vulnerable category as AOO < 20km2 and number of locations is <5.

Assessment: Sulcaria isidiifera may be assessed as Critically Endangered according to Criterion B1 (a,b), B2 (a, b) and Vulnerable according to Criterion D2.

Geographic range

This species is only known to occur in an area seven miles across in San Luis Obispo County, California.

Population and Trends

Populations of this lichen have been lost due to development (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).

Mediterranean-type Shrubby Vegetation


This species is threatened by residential development and changes in fire regimes.

Housing & urban areasFire & fire suppressionIncrease in fire frequency/intensityDroughts

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.

Site/area protectionSite/area managementSpecies managementSpecies recoveryReintroductionEducation & awarenessFormal educationTrainingAwareness & communicationsLaw & policyLegislationNational level

Research needed

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

Population size, distribution & trendsSpecies Action/Recovery PlanPopulation trends

Use and Trade


Brodo, IM 1986: A new species of the lichen genus Sulcaria (Ascomycotina, Alectoriaceae) from California. - Mycotaxon 27: 113-117.

T. Carlberg and K. Knudsen 2007: Sulcaria isidiifera, sponsorship for the CALS Conservation Committee. - Bulletin of the California Lichen Society 14(2): 45-47.

Known distribution - countries

Regional Population and Trends

Country Trend Redlisted