in Arup & al., Nord. J. Bot., 31: 36, 2013. Basionym: Verrucaria oblitterata var. holocarpa Hoffm. - Deutsch. Fl., 2, 179, 1796,
Synonyms: Athallia vitellinula ; Callopisma aurantiacum var. holocarpum (Ach.) A. Massal.; Caloplaca aurantiaca var. holocarpa (Ach.) Th. Fr.; Caloplaca holocarpa (Ach.) A.E. Wade; Caloplaca pyracea var. holocarpa (Ach.) Th. Fr.; Caloplaca vitellinula (Nyl.) H. Olivier; Lecanora vitellinula Nyl.; Placodium aurantiacum var. holocarpum (Ach.) Anzi; Placodium pyraceum var. holocarpum (Ach.) Anzi
Distribution: N - Ven, TAA, VA, Lig (TSB 33408). C - Tosc (TSB 21532), Marc (TSB 24077), Abr. (Gheza & al. 2021), Mol (TSB32538), Sar (B-189907). S - Camp, Bas (TSB 29938), Si.
Description: Thallus absent or developed only around apothecia, sometimes continuous, slightly cracked and verruculose; grey to grey-orange. Apothecia frequent, zeorine, 0.3-0.7(-l) mm across, with a flat to convex, yellow to orange disc and a concolourous or slightly paler proper margin. Proper exciple of irregularly radiating, thick-walled hyphae; epithecium orange, granular, K+ red; hymenium colourless,(55-)65-80(-100) μm high; paraphyses simple to sparingly branched in upper part, 2-2.5 μm thick at mid-level, the uppermost cells to 4-6 μm wide; hypothecium colourless, (25-)50-80(-100) μm high, sometimes inspersed with oil droplets. Asci 8-spored, cylindrical, Teloschistes-type. Ascospores 1-septate, polarilocular, hyaline, ellipsoid to broadly ellipsoid, (9.5-)10-13.5(-15.5) x (4.8-)5.5-7.5(-8.5) μm, the septum (3-)3.5-5(-5.8) μm thick. Photobiont chlorococcoid. Spot tests: thallus K- or K+ red, C-, KC-, P-; apothecia K+ red. Chemistry: apothecia and orange-pigmented parts of thallus (when present) with parietin (major), fallacinal, emodin, teloschistin and parietinic acid (minor).
Note: according to Arup (2009) this is a silicicolous, rarely lignicolous species of more or less eutrophicated habitats, mostly found on the top of isolated boulders. The epithet holocarpa, however, has been widely used for different lichens occurring both on bark and on calcareous rocks, which are mainly treated here under Athallia pyracea and Flavoplaca oasis. Due to the extreme confusion still concerning this group in southern Europe, I place here only a few records from siliceous rocks which I could check in TSB. On the synonymysation of Athallia vitellinula see Vondrák & al. (2016).