Description: This maritime species of damp siliceous rock has a pale brown to white superficial thallus with conspicuous perithecia (with involucrellum) and ellipsoid spores in the middle range for Verrucaria species (19–25 x 9–11.5µm). It is apt to be confused with V. muralis (see elsewhere) which, though lacking a superficial thallus on limestone pebbles, usually has one when growing on siliceous rocks; this however is often poorly developed by comparison and the spores narrower. The species is poorly known and consequently records are few.

Key Identification Features:

• Thallus whitish, superficial; spores in the middle range
• Look for it in the upper (‘grey’) lichen zone of maritime cliffs and shores where it occurs in the same habitat as coastal Ramalina species.

Original text submitted by Vince J. Giavarini

Distribution Map from NBN: Verrucaria internigrescens at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Verrucaria internigrescens at iNaturalist World Species Observations database.