Common Boulder Lichen vs Concentric Boulder Lichen

Porpidia macrocarpa compared with Porpidia crustulata

Key Differences

• Common Boulder Lichen is Near Threatened while Concentric Boulder Lichen is Vulnerable.

Taxonomic Classification

Rank	Common Boulder Lichen	Concentric Boulder Lichen
Kingdom same	Fungi (균계)	Fungi (균계)
Phylum same	Ascomycota (자낭균류)	Ascomycota (자낭균류)
Class same	Lecanoromycetes (요강버섯강)	Lecanoromycetes (요강버섯강)
Order same	Lecideales (Lecideales)	Lecideales (Lecideales)
Family same	Lecideaceae	Lecideaceae
Genus same	Porpidia	Porpidia
Species	Porpidia macrocarpa	Porpidia crustulata

Evolutionary Relationship

Common Boulder Lichen and Concentric Boulder Lichen share a common ancestor at the Genus level: Porpidia.

Conservation Status

Common Boulder Lichen

NT — Near Threatened

Concentric Boulder Lichen

VU — Vulnerable

Physical Characteristics

Attribute	Common Boulder Lichen	Concentric Boulder Lichen
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

Common Boulder Lichen

Habitat

Native to Europe and North America and South America, inhabiting ecosystems characteristic of the region.

Range

Widely distributed across Europe (4 countries), North America (United States), and South America (Colombia). Listed as Near Threatened, this species requires ongoing monitoring to prevent population decline.

Concentric Boulder Lichen

Habitat

Native to Europe and North America, inhabiting ecosystems characteristic of the region.

Range

Distributed across Denmark, Norway, Portugal, Sweden, and United States. Currently classified as Vulnerable on the IUCN Red List, this species faces significant conservation challenges across its range.

Common Boulder Lichen

The common boulder lichen (<em>Porpidia macrocarpa</em>) is a crustose lichen species with a wide distribution across Europe and the Americas, recorded in Colombia, Denmark, Norway, Portugal, Sweden, and the United States. This species typically inhabits siliceous rock surfaces in a variety of exposed terrestrial environments across both North and South America and Europe. The common boulder lichen is classified as Near Threatened on the IUCN Red List, suggesting that its populations face potential pressures and require monitoring. As a slow-growing crustose lichen, it often colonizes hard rock substrates including granite and quartzite, forming a close symbiotic relationship between its fungal and algal components. It plays an important role in the early stages of soil formation through the gradual weathering of rock surfaces. Biological traits of this species remain poorly documented in the scientific literature.

Concentric Boulder Lichen

<em>Porpidia crustulata</em>, commonly known as the Concentric Boulder Lichen, is a crustose lichen in the family Porpidiaceae formed through a symbiotic relationship between a fungal partner (mycobiont) and photosynthetic green algae (photobiont). Like all crustose lichens, it grows tightly appressed to its substrate—typically siliceous or acidic rock surfaces including boulders, cliff faces, and pebbles in open, well-lit habitats—forming thin, grayish to pale thalli marked by scattered black apothecia (reproductive discs). <em>Porpidia crustulata</em> derives nutrition entirely through photosynthesis conducted by its algal partner, requiring no external organic food source. The species has been documented in Denmark, Norway, Portugal, Sweden, and the United States, suggesting a broad boreal to temperate distribution across the Northern Hemisphere. It is currently classified as Vulnerable by the IUCN, indicating significant conservation concern, likely linked to threats including air pollution, acidification, quarrying of rocky habitats, and changes in land use that reduce the availability of suitable substrates. Crustose lichens are typically slow-growing, long-lived organisms with limited capacity for rapid range shifts in response to environmental change. Biological traits such as individual lifespan, growth rates, and reproductive output remain poorly documented at the population level.

Shared Countries

Both species can be found in 5 countries:

🇩🇰 Denmark 🇳🇴 Norway 🇵🇹 Portugal 🇸🇪 Sweden 🇺🇸 United States