Arthonia atra

Ascomycota › Arthoniomycetes › Arthoniales › Arthoniaceae › Arthonia

Description

A thin white to pale-grey crust with numerous raised black lirellae. These narrow fruiting bodies may be simple or branched, and their discs usually remain slit-like.

Source: ITALIC — Arthonia atra

Chemistry

Thallus: usually K−, occasionally faintly K+ yellow; C−, KC−, P−, UV−. No characteristic lichen substances are reported. The epithecium and inner exciple can turn olive-green with K in section.

Source: ITALIC — Arthonia atra

Habitat and Substrate

A bark-dwelling species of temperate regions, occurring especially on smooth tree bark.

Source: ITALIC — Arthonia atra

Similar Species

Compare Graphis scripta and other script lichens. Older literature uses the name Opegrapha atra.

Sources: ITALIC; BLS identification revision

How to Identify

Use the Arthoniaceae key; check the carbonised exciple, asci and three-septate spores.

Source: BLS identification revision

Important Links

ITALIC — description, chemistry and images

British Lichen Society — species account and British distribution

GBIF — taxonomy and global occurrence records

AFL — species account and photographs

Identification Bibliography

Cannon, P., et al. (2020). Arthoniales: Arthoniaceae. Revisions of British and Irish Lichens, 1, 3–48.

Nimis, P. L., et al. ITALIC: The Information System on Italian Lichens. Online account: Arthonia atra.

For identification, use the relevant key and compare the microscopic characters and chemical reactions. Photographs alone may be insufficient for closely similar crustose species.