Thallus small, 2-4 mm diam. or irregular and following contours in the rock, areolate. Areoles (200-) 350-500 (-700) µm diam., 150-250 μm thick, irregular, usually polygonal, the surface flat or shallowly convex, grey-brown, not or thinly white-pruinose. Upper cortex 15-20 μm thick, of 1-2 (-3) layers of cells, epinecral layer patchy and variably developed, 0-15 μm thick. Algal layer 65-95 μm thick, with algal cells 8-14 μm diam. Medulla weakly J+, 80-130 μm thick, fairly dense, with abundant crystals from the substrate, in places with necrotic brown parts of the host lichen.
Anamorph: conidiomata not seen.
Teleomorph: ascomata perithecia, 105-140 μm diam., completely immersed, rarely prominent, 1-3 (-5) in each areole, visible from above due to blackening around the ostiole. Peridium 13-20 μm thick, hyaline except for a small apical area of brown pigmentation, involucrellum not clearly distinguished. Interascal tissue absent, periphysoids 14-22 × 2.5-4 μm in size. Asci 40-55 × 17-26 μm, clavate to saccate, rather thin-walled, 8-spored. Ascospores (12.5-) 13.5-15 (-16) x (5-) 5.5-6.5 μm, ellipsoidal, L/W ratio 2.0-2.4, 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, and by host preference. More research is needed into these distinctions, and to link them to sequence-based characteristics. Most similar to Verrucula tarraconensis, described as a parasite of Variospora velana (not recorded from the UK).
Initially parasitic on thalli of Caloplaca s.l., then becoming established as an independent lichen.
In GB&I, only known from a single site in VC45 Pembrokeshire.
On hard limestone, on a maritime clifftop.