Miriquidica squamulosa Fryday
Lichenologist 40: 286. 2008

Thallus pinkish-brown to pale grey, effuse, but rarely extensive, to 2 cm, often of ± dispersed areoles, or on a black hypothallus when contiguous, areoles flat to strongly convex, (0.5–)0.8–1.5(-2.5) mm with ± lobulate margin, 0.2–0.25 mm thick, with a dark (K+ purple-red) lower surface, forming squamules up to 5 mm across; pale brown immersed pycnidia usually present but rarely abundant. Upper cortex 30–50 µm thick, composed of vertically arranged hyphae 3–4 µm thick, upper 5–10 µm pale- to mid-brown, cells brown pigmented, epinecral layer absent. Basal layer 40–50 µm thick, dark red-brown (K+ purple-red) forming a “root” to 0.25 mm deep. Primary photobiont chlorococcoid, cells 10–12(–15) µm. Secondary photobiont cephalodia, frequent when present, black, rounded to angular, flat to slightly convex, 0.8–1.5 µm, between areoles, surface rough, cyanobacterium ?Chroococcus, cells bright blue, 3-5 µm across, at surface yellow brown, 3-4 enclosed together in a darker sheath 8–10 µm across.
Apothecia usually frequent, lecideine, immersed in the thallus, often compound, some occasionally singular and simple; black, usually convex and immarginate, rarely flat with persistent, thin (0.05 mm thick) and barely raised, black margin. Hymenium 70–80 µm high, hyaline, upper 10-15 µm dark blue-green, I+ blue, merging below with dilute red-brown zone of hypothecium; paraphyses slender, sparingly branched and anastomosing, swollen at apex to 3–4 µm and dark pigmented with distinct cap. Hypothecium upper 70–80 µm dilute red-brown, lower 100–150 µm dark brown (K+ red purple). Asci ? Lecanora-type (I+ tholus, with a feint ocular chamber), broadly cylindrical to subclavate, 50–55 × (12–)15–18 µm; ascospores 8/ascus, simple, hyaline, broad ellipsoid (9–)10–12 × (5–)5.5––6.5(–7) µm. Exciple dark brown 20–30 µm wide.
Conidiomata: Pycnidia, usually present but abundant on only one collection (Imshaug 46802), pale brown, immersed, usually round (rarely linear), 0.05–0.15 × 0.05–0.1 µm. Conidia filliform, curved, c. 20 µm long.

Chemistry: K+ yellow becoming red (acicular crystals in section), Pd+ orange, C–, UV–; norstictic acid and accessories by TLC.

Distribution & Ecology: Miriquidica squamulosa is known only from Campbell Island , where it grows over bryophytes (e.g., Andreaea sp. Gymnomitrion sp.) on siliceous rocks on the summits of mountains. One collection (Imshaug 46802) is apparently growing directly on siliceous rock, but another collection from the same locality (Imshaug 46794) is clearly growing over bryophytes

Notes: Miriquidica squamulosa is the only known species of the genus that is not primarily saxicolous, although M. lulensis (Hellb.) Hertel & Rambold, which also contains norstictic acid, has been reported as growing over bryophytes (Fryday 2006). However, that species has a white areolate thallus, black sessile apothecia, and a hyaline hypothecium. Other described species that also contain norstictic acid also have either a hyaline hypothecium (M leucophaeoides (Nyl.) Andreev) or a granulose-verrucose thallus (M. paanaënsis (Räsänen & Laurila) Andreev) and are known only from siliceous rocks in the boreal-subarctic region.

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Thallus and Apotheica