Mycobank No.: MB521387

Stigmatidium graphidioides Cromb., J. Linn. Soc. London, Bot. 15: 233 (1876); type: [Chile], ‘on a hill, Swallow Bay (Fuegia), ad saxa granitica. 30 December 1868’, R. O. Cunningham (E!). Lithographa subantarctica Hertel & Rambold, Bibl. Lichenol. 38: 158 (1990); type: Prince Edward Islands, Marion Island: Tafelberg, 46(53#S 37(48#00–45$E, 350 m, stone lying on ground of the windswept summit plateau, 10 v 1982, H. Hertel 24585a (M–holotype!).

Description:

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: thallus 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 × 7µm.

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 [margin]; 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. 15µm 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 42°S to 54°51'S, being particularly frequent in southern South America. 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.