Verrucaria macrostoma Verrucariaceae
Verrucaria macrostoma f. macrostoma

Growth type crustose
Chemical reactions negative.

Occurs on calcareous rocks, limestone and on mortar

The well-developed, mid-brown thallus is darker in exposed locations but paler brown in shade with rounded or lobed areoles often cracking into large secondary areoles. Areoles are +/- subsquamulose, the black perithecia (3/4 immersed) not leaving pits when decayed.

Similar: V. macrostoma f. furfuracea is blastidiate, perithecia absent.
V. nigrescens has smaller aureoles, usually darker in colour

Verrucaria macrostoma

Verrucaria macrostoma
Verrucaria macrostoma
Wool churchyard, Dorset. September 2012. Rollright Stones, Oxfordshire, September 2011

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