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

Mobergia calculiformis (W.A. Weber) H. Mayrhofer & Sheard

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Scientific name
Mobergia calculiformis
(W.A. Weber) H. Mayrhofer & Sheard
Common names
Coastal Popcorn Lichen
Palomitas Costeras
IUCN Specialist Group
Assessment status
Under Assessment
Proposed by
Jessica Allen
Frank Bungartz
Frank Bungartz, Manuela Dal Forno, María de los Angekes Herrera Campos, Christian Parrinello, Daniel Ramos, Reinaldo Vargas
Jessica Allen, Jason Hollinger, Daphne Stone

Assessment Notes

still needs habit photos
still needs literature, especially on Baja Race and Escalera Nautica
still needs map of current and historic distribution
needs KML file


A2a,c - we estimate at least a 50% overall population reduction based on:
50% of the extant subpopulations are in protected areas, one of those is impacted by tourism, the other one might be affected in the future by the Escalera Nautica and is even threatened by currently ongoing infrastructure projects; all US subpopulations are already extirpated, the other 50% extant subpopulations are either minute (Sierra La Giganta) and/or threatened by urbanization (Sierra La Giganta and south of San Quintín).

Although the EOO is large, the AOO is less than 70km2 and we have severe fragmentation of the subpopulations, plus a continuing decline in extent of occurrence, area of occupancy, and at least projected decline of the number of locations and subpopulations.

Taxonomic notes

Mobergia is an unusual genus in the Physciaceae with only two species. The unusual conspicous “popcorn” morphology makes this species extremely easy to recognize.

Why suggested for a Global Red List Assessment?

The historic reports from the US are now all extirpated. In Baja California and Baja California Sur several viable subpopulations exist along the Pacific coast, the most northern one below San Quinitin is heavily impacted and in part eradicated by agriculture and urbanization. The one on the islands is a popular tourist site. The one near the fishermen town Santa Rosaliíta is in danger from the Escalera Nautica (a road building project). The one in Baja Sur is very small at the western flanks of the Sierra de la Giganta.

Geographic range

Originally reported from coastal California (USA) and both Baja California and Baja California Sur (Mexico). All US locations have been revisited by K. Knudsen (pers. comm.) who confirmed that these subpopulations are now extirpated.
This leaves the Mexican sites (almost all in Baja California) as the only surviving subpopulations. The only one from Baja California Sur has not recently been confirmed.
Using the known extant sites from the Baja peninsula GeoCat calculates EEO as 108,000 Km2 and the AOO as 72km2. The relatively large EEO is a result of the specimens from Guadalupe Island, much off the coast, almost 250 km away from the mainland peninsula.

Population and Trends

All US subpopulations are extirpated. In Mexico we can distinguish 4 IUCN locations still extant:
(1) subpopulation immediately south of San Quintín is very heavily urbanized and the habitat has drastically changed.
(2) subpopulation near Santa Rosaliíta is still in very good shape, the small fisherman village not much frequented by tourism and the species relatively abundant according to an informal survey by F. Bungartz & R. Vargas in May 2018; but this location will be very drastically changed, if the Mexican government approves the Escalera Nautica project (plans to criss-cross the peninsula with a network of roads to allow tourists to move their sailing boats from the Pacific to the Sea of Cortés).
(3) subpopulation on Guadalupe Island recently became a biosphere reserve; although in a protected area this subpopulation is today heavily impacted by tourism and its accompanying development.
(4) subpopulation on the western flanks of Sierra La Giganta is not well documented and the southernmost outlier, Ciudad Insurgentes further south is a huge, heavily urbanized area, at the Pacific coast near the port of Adolfo Lopéz Mateos a large seashore resort is being built.

Population Trend: Decreasing

Habitat and Ecology

The species is semi-vagrant, saxicolous and attached to pebbles and larger coastal rock, cliffs, and boulders. It occurs only along the Pacific coast in a heavily fog-induced desert of the Baja peninsula (when similar habitat had still not been replaced by urban and agricultural development in the US, the species presumably was common there too).

HotRocky ShorelineSea Cliffs and Rocky Offshore Islands


The northernmost extant subpopulation south of San Quintín is very heavily impacted by agricultural and urban development as well as tourism. These populations are currently not protected.
Specimens at the subpopulation along the pacific coast between El Rosario and Santa Rosaliíta are still very abundant and currently may be considered the ones best preserved. These sites are at least in part located in and near the Parque Natural del Desierto Central de Baja California, but the sites are nevertheless projected to be heavily developed as part of the Escalera Nautica project. Like most of the Baja desert sites an additional threat are the various off-road races (e.g., Baja 1000 Race).
A single, isolated location with another subpopulation in Sierra Giganta in Baja Califfornia Sur is poorly known (has not been visited since 1989), but the site lies just north of the heavily urbanized city of Insurgentes. 
The site of the subpopulation inside the Guadalupe Island Biosphere Reserve is healthy, but sites are impacted by tourism.     

Housing & urban areasCommercial & industrial areasTourism & recreation areasShifting agricultureSmall-holder grazing, ranching or farmingScale Unknown/UnrecordedMining & quarryingRenewable energyRoads & railroadsUtility & service linesShipping lanesFlight pathsRecreational activitiesRun-offSoil erosion, sedimentationHabitat shifting & alteration

Conservation Actions

Most current conservation actions are focusing on the preservation of plant habitat and habitat for birds and small mammals, but lichens are still largely ignored. Raising public awareness for the very unique lichen biota of the peninsula is critically important and particularly on the Pacific site the sensitive fog desert habitat needs to be better protected from a broad range of destructive impact: tourism, off-road driving (e.g., Baja 1000 race), urbanization, infrastructure, agriculture, etc.

Site/area protectionSite/area managementNational level

Research needed

The current size and extent of the different subpopulations are insufficiently known. Some sites (e.g. Sierra La Giganta, Baja California Sur) have not recently been visited and need to be surveyed whether the species there still persists. Others, like Guadalupe Biosphere Reserve are formally protected by law, but no actual species management plans focusing on lichen preservation have been developed. Species Action/Recovery Plans need to be developed urgently for the locations close to population centers/urban and agricultural areas (e.g., south of San Quintín).

The species is one of two unique ones in the genus and taxonomically easily recognized, large and conspicuous, but its population trends are virtually completely unknown.

Population size, distribution & trendsLife history & ecologyThreatsActionsSpecies Action/Recovery PlanArea-based Management PlanPopulation trendsHabitat trends

Use and Trade



Mayrhofer, H., Sheard, J.W. (2004) Mobergia. In: Nash, TH, III, Ryan, BD., Diederich, P., Gries, C. & Bungartz, F (eds.): Lichen Flora of the Greater Sonoran Desert Region, Vol. 2. Lichens Unlimited, Arizona State University, Tempe, Arizona, pp. 364-365.
Mayrhofer, H., Sheard, J.W. & Matzer, M. (1992) Mobergia (Physciaceae, lichenized Ascomycetes), a new genus endemic to western North America.  The Bryologist 95(4): 436-442.
Spjut, RW 1995: Occurrence of Mobergia calculiformis (Physciaceae, Lecanorales) in the northern Vizcaino Desert of Baja California, Mexico. In: Daniëls, FJA, Schulz, M. & Peine, J. (eds.): Flechten Follmann. Contributions to lichenology in Honour of Gerhard Follmann. Geobotanical and Phytotaxonomical Study Group, Botanical Institute, University of Cologne, Cologne, pp. 475-482.
Bellemere, A 1994: A propos de genres nouveaux de Lichens (1992). Bulletin d’Informations de l’Association Française de Lichénologie 18(2): 7-12.

Escalera Nautica Project: https://www.cielomarbaja.com/​escalera-nautica-nautical-ladder/

Known distribution - countries

Regional Population and Trends

Country Trend Redlisted