Flora of New Zealand Series

≡Porina decipiens Malme, Ark. Bot. 23A (1): 26 (1929).

Description : Thallus crustose, epilithic, determinate, forming rounded colonies up to 5 cm diam., continuous to cracked, sometimes peeling from substratum, glossy towards margins, otherwise matt, smooth, pale khaki-grey to pale greenish grey (darker in shade), interspersed with rock fragments and crystals, 20–50(–70) μm thick, thinly corticate. Cortex ±prosoplectenchymatous, 9–15 μm thick. Prothallus silvery-white, not apparent. Perithecia numerous, solitary, occasionally paired, ⅓ immersed to ±entirely immersed in thallus or overgrown by a thin, thalline layer, usually appearing dark greyish brown rather than black; apex conical to subconical; ostiole apical, inconspicuous or in a shallow depression 40–70 μm wide, often paler than involucrellum. Involucrellum apical or extending midway to base of excipulum, usually smooth, occasionally delicately radially rugose, (0.18–)0.26(–0.34) mm diam., 30–70 μm thick. Exciple uniformly hyaline or darkening towards apex, 10–20 m thick. Paraphyses persistent, simple to sparingly or occasionally richly branched, 1–2(–2.5) μm thick. Periphyses absent. Asci fissitunicate, narrowly to broadly cylindrical, 52–88 × 9–15 μm, contents IKI+ red-brown, walls IKI−, apical dome 2–5 μm thick, ocular chamber hemispherical, tubercular or conical, 1–2 μm broad and tall. Ascospores colourless, 5–7-septate, fusiform, elongate-cylindrical or irregularly curved or subsigmoid, often tapering towards proximal end and markedly constricted at primary septum, thin-walled, uniseriate (15.5–)22(–28.5) × (4.5–) 6(–8.5) μm, contents clear to coarsely granular. Pycnidia absent to numerous, semi-immersed, brown-black above, colourless below, 40–80 μm diam. Microconidia fusiform to bacillar, 2–3(–4) × 0.5– 1 μm. Macroconidia not seen.

S: Otago (Bethune's Gully Mt Cargill, Morrison's Creek Leith Valley). On shaded basaltic rocks in streambeds. Known also from Australia, Lord Howe I. and Brazil (McCarthy 1997, 2003c, 2006).

Pantropical

Illustration : McCarthy (1997: 514, fig. 1).

Strigula decipiens has the thin, pale, smooth and somewhat glossy thallus common to most saxicolous species of Strigula. However, its perithecia have an unusually pale and poorly developed involucrellum, and the 5–7-septate ascospores are exceptionally small (McCarthy 1997: 515). S. decipiens may be the correct name for specimens from E Australia and New Zealand incorrectly identified as S. stigmatella var. alpestris (Vězda) Coppins (McCarthy & Malcolm 1996b; McCarthy et al. 1996a) and S.aff.stigmatella (McCarthy & Johnson 1998).