Arthonia meridionalis Arthoniaceae
Arthonia meridionalis

Growth type crustose. Chemical results negative
BLS conservation evaluation: VU D2 NR

A Mediterranean and southern Atlantic species that has only been recorded in Britain from the Isle of Portland, Dorset. It occurs on limestone rocks and stones in sheltered, well-lit hollows below large boulders.

Forms irregular, slightly raised patches of chalk-white thallus with numerous round or slightly elongated apothecia. The apothecia are black, thinly white pruinose and either immersed or level with the thallus. Asci 8-spored, spores colourless, 1-septate, 12-15 4.5-6 m. Photobiont trentepohlioid.

Similar: Diplotomma alboatrum has muriform spores


Arthonia meridionalis

Arthonia meridionalis

Arthonia meridionalis
Arthonia meridionalis
On limestone, Portland, Dorset. February 2016

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