Porpidia crustulata

The common name "concentric boulder lichen" refers to the striking concentric circles of dark apothecia (fruiting bodies) that often develop on top of the light gray thallus. P. crustulata specimens are sometimes mistaken for their close relatives Porpidia macrocarpa, but P. crustulata can be distinguished by its smaller apothecia and thinner margin.{{cite journal | title=The lichen genus Porpidia in Poland I. P. cinereoatra and P. crustulata| author=Agnieszka Jabłońska | journal=Herzogia | url=https://blam-bl.de/images/Herzogia_21/H21-Jablonska_full.pdf}}

Porpidia crustulata has been measured to grow at a rate of 0.4-0.6 mm in diameter per year. The same study indicated that the photobiont layer thins as the lichen grows, potentially limiting the maximum size of individual lichens to around 8 cm diameter. Additionally, the study used scanning electron microscopy to identify the partner photobionts of their sampled lichens as two variants from the genus Chlorella: Chlorella "sp. GC" and free-living Chlorella sorokiniana.{{cite journal |author=Li Bo |title=Relationship between the algal partners and the growth of lichen-forming fungus Porpidia crustulata |journal=Symbiosis |date=2014 |volume=62 |issue=2 |pages=101–109 |doi=10.1007/s13199-014-0275-1|bibcode=2014Symbi..62..101L }}

Porpidia crustulata have been observed over a wide range, including the Americas, Africa, Eurasia, Australia, and Greenland.{{cite web |title=concentric boulder lichen (Porpidia crustulata) |url=https://www.inaturalist.org/taxa/182467-Porpidia-crustulata |access-date=26 May 2025 |website=iNaturalist |language=en-US}} It can live in climates ranging from temperate to alpine/arctic.

In North America it is more common in eastern temperate and southern boreal regions, and rarer in the west.{{cite journal | title = The Lichen Genus Porpidia (Porpidiaceae) in North America | author=Sharon Gowan | journal= The Bryologist | date=1989 | volume=92 | issue=1 | pages=25–59 | doi=10.2307/3244016| jstor=3244016 }}

Porpidia crustulata is thought to prefer siliceous rocks, especially pebbles, in exposed locations. However, it has also been observed growing on non-calcareous rocks like sandstone and granite, bricks, mortar, an old leather shoe, and wood.

{{Empty section|date=May 2025}}

{{Empty section|date=May 2025}}

{{Reflist}}

{{Taxonbar|from=Q10567565}}

Category:Lichen species

Category:Lecideales