Thallus effuse, ochraceous, thin, continuous to weakly rimose, or exceptionally thicker and partly rimose-areolate with angular areoles c. 0.2–0.5 mm wide; prothallus not evident. In section to 100 µm thick, exceptionally to 200 µm; ecorticate, but with 5–12 µm tall epinecral layer; medulla containing many mineral fragments; I+ weakly blue, but reaction often patchy or obscured by mineral fragments. Photobiont cells 5–8 µm diam. or ellipsoid and to 9 × 7 µm.
Apothecia usually lirelliform, 0.25–1.15 × 0.2–0.4 mm, straight to curved, simple or with 1(–4) branches, but occasionally rounded and ‘Rimularia’-like, sometimes even with a central ‘umbo’; black, usually becoming emergent and with raised margins and obtuse apices, sometimes a few lirellae are more innate with a slit-like disc, a seemingly narrower margin and acute apices; margin 0.07–0.3 mm wide, when raised often with a few transverse cracks; disc sunken, usually expanded but sometimes slit-like. Exciple cupulate, reddish brown, K+ brown-red pigment going into solution, N–, 60–195 µm thick at base, 37–74 µm laterally and 60–147 µm at the apex; the upper part often spreading outwards (‘involucrellum’-like) onto the surrounding thallus (or adhering portion of thallus). Hymenium c. 75–100 µm tall, hyaline, I+ blue; epithecium indistinct or present as a reddish brown layer c. 15 µm tall. Hypothecium 26–34 µm tall, dilute red-brown. Paraphyses distinctly septate but not moniliform, 1.7– 2 µm wide, not swollen at apices, but apices sometimes surrounded by a brown-pigmented ‘hood’ 3–3.5 µm wide. Asci clavate, 62–75 × 17–24.5 µm, 8-spored; in K/I with amyloid outer wall, and tholus with a thin amyloid apical cap and amyloid flanks (Trapelia-type). Ascospores (10–)12–17 × (5.5–)7–9 µm, ellipsoid or broadly ovoid-ellipsoid, simple, hyaline, sometimes with a thin perispore.
Pycnidia usually present but rarely abundant, immersed, black, 60–100 µm diam.; wall reddish brown. Conidia narrowly bacilliform, 6–11(–13) × c. 0.8 µm.
Chemistry. Thallus K–, C–, KC–, P–, UV–; no substances detected by TLC.
Ecology and distribution. On siliceous rocks and stones, at altitudes from near sea-level to 1320 m. Lithographa graphidioides is a widely occurring species in the southern subpolar region at latitudes 42ºS to 54º51´S, being particulalry frequent in southern South Americ. It is known from Tasmania (Hertel & Rambold 1990) and has recently been reported from South Island, New Zealand (Galloway 2007), but is apparently absent from the Auckland Islands and Campbell Island.
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