Thallus small, 2-4 mm diam. or irregular and following contours in the rock, areolate. Areoles (200-) 350-500 (-1000) µm diam., 150-250 (-300) μm thick, irregular, usually polygonal, the surface flat or shallowly convex, grey-brown, not or thinly white-pruinose, the radial sides often dark brown. Upper cortex 8-15 μm thick, of 1-2 (-3) layers of brown-walled cells, epinecral layer patchy and variably developed, 0-30 μm thick. Algal layer 65-120 μm thick, with algal cells 8-17 μm diam. Medulla not or weakly J+, 80-180 μm thick, fairly dense, with abundant crystals from the substrate, in places with necrotic brown parts of the host lichen.
Anamorph: conidiomata pycnidia, in locules within the thallus, the walls hyaline, mid brown immediately around the ostiole. Conidiogenous cells conical to doliiform, proliferating peruccrently. Conidia 4-5.5 × 0.5-1 μm, narrowly bacillar, aseptate, hyaline.
Teleomorph: ascomata perithecia, 105-175 μm diam., completely immersed, rarely prominent, 1-3 (-5) in each areole, visible from above due to blackening around the ostiole which may appear distinctly papillate. Peridium 10-15 μm thick, hyaline except for a small apical area of brown pigmentation, composed of 3-4 layers of rather thick-walled flattened cells. Involucrellum not clearly present. Interascal tissue absent, periphysoids 14-22 × 2.5-4 μm in size. Asci 45-60 × 13-18 (-26) μm, clavate to saccate, distinctly thick-walled when young but rather thin-walled at maturity, 8-spored. Ascospores (12.5-) 13.5-15 (-16) x (5-) 5.5-6.5 μm, ellipsoidal, L/W ratio 2.2-2.6, mostly aseptate but with a small proportion (~10%) with a median septum, hyaline, thin- and smooth-walled, without an epispore, gelatinous sheath or appendages.
Not assessed. More research is necessary before a conservation assessment is appropriate.
Part of the Verrucula latericola complex, distinguished from that species by its smaller thalli and areoles, narrower ascospores, and perhaps also by host preference. More research is needed into these distinctions, and to link them to sequence-based characteristics.
Initially parasitic on thalli of Caloplaca s.l., then becoming established as an independent lichen.
In GB&I, only known from various sites in the maritime west, including Cornwall, Devon, N Somerset, Glamorgan, Pembrokeshire and Caernarvon. Probably more widespread; it appears common in maritime areas of the Netherlands.
On hard limestone, on a maritime clifftop.