Thallus continuous, forming neatly delimited patches, smooth to roughened or warty, pale grey or sometimes yellow-grey. Prothallus absent (black zone lines can sometimes form between genetically disinct colonies). Isidia and soralia absent. Photobiont chlorococcoid.
Anamorph: Conidiomata pycnidia. Conidia 10-14 μm long, cylindrical.
Teleomorph: ascomata apothecia, 0.4-0.8 (-1.5) mm diam., sessile, often aggregated. Thalline exciple well-developed, peristent, entire to irregularly crenulate or slightly warted, the medulla with massive irregular crystal clusters not dissolving in K. Disc flat, pale dull brown to rose-, orange- or red-brown, not or rarely slightly pruinose. Epithecium hyaline to grey-brown, overlain with numerous coarse granules (epipsamma) soluble in K and N. Hymenium 70-95 μm tall. Interascal tissue of paraphyses 1.5-2 μm diam., simple or sparsely branched, apices 2.5-4 μm diam., slightly swollen and yellow-brown, not capitate. Asci 65-80 × 10-15 μm, subcylindrical to elongate-clavate, 8-spored. Ascospores (9-) 11-13 (-15) × 6.5-7.5 (-8.5) μm, broadly ellipsoidal, aseptate, fairly thin-walled, smooth, without an epispora, gelatinous sheath or appendages.
Chemistry: thallus C–, K+ yellow, Pd–, UV reflecting mauve-purple (atranorin, gangaleoidin, ± roccellic acid, ± californin).
Assessed by Woods & Coppins (2012) as of Least Concern. Considered to be the commonest corticolous member of the Lecanora subfusca group in the region.
Care should be taken when separating the superficially similar and primarily saxicolous Lecanora campestris; specimens on timber require TLC to separate them with certainty. Black pycnidia of Vouauxiella species often occur at the junction between the exciple and disc; infected apothecia are generally discoloured. L. pulicaris differs in the Pd+ red exciple and the red to orange-brown epithecium with fine granules, not soluble in N. Specimens with well-developed,
irregularly warted thalline exciple and coarsely uneven-warted thallus are sometimes called L. rugosella. See also L. argentata, L. horiza and L. populicola. Small-fruited specimens resemble Lecania fuscella.
Throughout the British Isles, except in the most polluted areas. BLS map here.
On bark and wood, mainly of deciduous trees and also worked timber.