Athallia scopularis (Nyl.) Arup, Frödén & Søchting

in Arup et al., Nordic J. Bot. 31, 1: 36 (2013).

Basionym: Lecanora scopularis Nyl., Flora, Regensburg 66: 105 (1883).


Type locality: United Kingdom, Scotland, Aberdeenshire, Porthlethen, Kincardineshire, maritime rocks, Crombie (H-NYL 30553 - lectotype). Designated by Nordin 1972: 39).

Description: Lichen. Thallus crustose, epilithic, placodioid, tightly to loosely attached to substratum, forming confluent rosettes 1.5-4 mm in diam., yellow, orangish-yellow or ochraceous-yellow, without pruina, K+ (purple), occasionally surrounded by a faintly developed prothallus, same color as thallus. Areoles 0.3-0.6 mm in diam., convex and irregular, with abundant globose projections that give rise to young apothecia. Marginal lobes strongly convex, sometimes flattened and broadened toward tips, irregularly branched slightly imbricate, and divided by deep furrows, 0.4-2 mm long and 0.3-1 mm wide. Thallus in section 150-300 µm thick. Upper cortex 10-65(80) µm thick, with an orange outer layer 5-16.5 µm thick, and a hyaline inner part 5-50 µm thick, scleroplectenchymatous type B to sclero-prosoplectenchymatous, with rather distinct anticlinal hyphae (perpendicular to the surface) formed by hyaline cells of lumina 2.5-11.5 x 1.7-5 µm, without crystals when examined with polarized light, but with a quite visible epinecral layer. Algal layer 40-100 µm thick, arranged in clusters divided by bundles of anticlinal hyphae. Photobiont chlorococcoid, with globose cells 5-18 µm in diam. Medulla dense, with thick-walled hyphae 3-5 µm thick. Apothecia pseudolecanorine or zeorine, 0.2-1.2(1.8) mm in diam., highly abundant, rounded, formed from globular projections in the thallus, covering most of the areoles, verrucules and marginal lobes, prominent and nearly stipitate at the end. Disk mostly flat or faintly convex, ochraceous-yellow to bright orange, without pruina, K+ (purple), smooth. Proper margin, when distinguishable, lighter than disk, slightly prominent and persistent, 30-50(80) µm wide, thalline margin same color as thallus, usually prominent and persistent, but sometimes hidden at the base of apothecia and then crenulated, 50-100(200) µm wide. Epihymenium 6-12 µm thick, brownish-orange, K+ (purple). Hymenium 50-90(100) µm tall, hyaline. Subhymenium and hypothecium hyaline, the latter sclero-prosoplectenchymatous. Algal layer more or less continuous beneath the hypothecium. Hyphae beneath the algal layer clearly distinguishable and densely arranged. Parathecium 60-90(110) µm wide, sclero-prosoplectenchymatous, becoming scleroplectenchymatous type A or B towards the margin. Paraphyses septate, articulate, scarcely branched, 1.5-3.5(5) µm wide at the base, with two or three swollen epical cells [Zeile auf der Kopie nicht lesbar!]. Ascospores eight per ascus, polarilocular, hyaline, narrow ellipsoid (11)12-14-15.5(16.8) x (5.5)6-6.8-7.5(8) µm, with an equatorial thickening ("septum") (3.8)5-5.6-6.5(7) µm, a length/width ratio (1.4)1.7-2.1-2.4(2.6) and a length/equatorial thickening ratio (2)2.3-2.5-2.8(3.3) [n = 90] (Gaya 2009: 119-120).

Photobiont: Green alga.

Chemistry: No lichen substances (Gaya 2009: 119-120).