Dermatocarpon luridum
Dermatocarpon luridum
Dermatocarpon luridum and the other members of the genus Dermatocarpon are commonly called stippleback lichens because they have fruiting structures called perithecia that are flask-shaped structures embedded in the nonfruiting body (thallus), with a hole in the top to release spores, causing an appearance of being covered with small black dots.
Thallus a mat of multiple lobes up to approx. 15mm in width, grey or pale to dark brown, lacking pruina, bight green when wet, lobes lacking rhizines but thallus with holdfasts, medulla in section reacting red with Melzer's reagent (the only British Dermatocarpon to do so); fruitbodies perithecia, immersed in groups in the thallus. Locally frequent on wet rocks, generally on the margins of lochs and rivers where it may be periodically submerged.
Thallus a mat of multiple lobes up to approx. 15mm in width, grey or pale to dark brown, lacking pruina, bight green when wet, lobes lacking rhizines but thallus with holdfasts, medulla in section reacting red with Melzer's reagent (the only British Dermatocarpon to do so); fruitbodies perithecia, immersed in groups in the thallus. Locally frequent on wet rocks, generally on the margins of lochs and rivers where it may be periodically submerged.