Jelly lichen

Arctomia fascicularis is a lichenized fungus forming a jelly-like, gelatinous thallus that swells when wet, a texture arising from its association with cyanobacterial photobionts rather than green algae. As a member of the Arctomiaceae, it grows in small, often inconspicuous colonies on bark, mossy substrates, or rock surfaces in humid, sheltered microhabitats. Like other cyanolichens, it likely contributes to nitrogen fixation within its ecosystem, enriching substrates and supporting nutrient cycling in the forest communities it inhabits.

The species has an unusually broad but highly fragmented distribution, with records spanning temperate, boreal, and some subtropical and tropical regions across Europe, the Americas, Africa, Asia, and Oceania, including Norway, the United Kingdom, New Zealand, Chile, Japan, and Kenya, among many others. It occurs exclusively in terrestrial habitats, generally tied to specific humidity and shade conditions.

No reliable population figures exist, and the population trend is currently unknown, though the species is classified as Critically Endangered. Its persistence is threatened by ongoing deforestation and habitat fragmentation, conversion of land for agriculture, and shifts in microclimatic conditions linked to climate change, which affect the moisture levels the species depends upon. Competition from invasive species and the vulnerability inherent in small, isolated populations further compound the risk, increasing susceptibility to genetic bottlenecks.

Conservation actions specific to this species are not well documented, though it likely benefits indirectly from forest protection and habitat conservation programs in the countries where it occurs. Given its sensitivity to microhabitat disturbance, ongoing fragmentation, and lack of population monitoring, its outlook remains precarious, with continued decline probable in the absence of targeted habitat safeguards.

Occupies temperate montane forests with dense understory vegetation between 800-2,200m elevation, particularly favoring areas with high humidity and stable temperature regimes. Requires specific microhabitat conditions including fallen logs, moss-covered rocks, and areas with consistent moisture levels.