Fissurina subcontexta
≡Graphis subcontexta Nyl., Bull. Soc. linn. Normandie sér. 2, 2: 79 (1868).
Description : Thallus olive-green to brownish green, thin to thick, areolate, the areolae angular and separated by very narrow cracks. Surface convex to plane or lumpy, smooth, matt or shining in parts. Apothecia lirellate, conspicuous, scattered to numerous and crowded, curved and sinuous to straight, rarely branched, 4–10 mm long and (0.3–)0.4–0.8(–1.0) mm wide, partly immersed at first becoming sessile, lips closed or sometimes slightly open, sometimes slightly sulcate; proper exciple reddish brown, uncarbonised or slightly apically carbonised, open at base to sometimes almost closed. Hymenium 100–125(–150) μm tall. Ascospores uniseriate in ascus, rounded–oblong, 4-locular, (13–)15–21(–25) × 6–8(–9) μm.
Chemistry : TLC−, all reactions negative.
N: South Auckland (Mt Moehau, Coromandel Peninsula), Wellington. On bark of coastal trees and shrubs, often with Stirtoniella kelica (q.v.). Known also from northern Australia and New Caledonia (Archer 1999b: 283; McCarthy 2003c, 2006).
Palaeotropical
Illustrations : Archer (1999b: 280, fig. 2E – as Graphis subcontexta); Staiger (2002: 150, fig. 40; 493, fig. 219).
Fissurina subcontexta is characterised by: the corticolous habit; the large, conspicuous, sessile, lirellae; small, 4-locular ascospores, (13–)15–21 × 6–8(–9) μm; and an absence of secondary metabolites. The appearance of lirellae is variable as the colour depends on the degree of exposure of the reddish brown proper exciple. When concealed by the thalline margin the lirellae appear whitish or creamish, but with a less well developed thalline margin the reddish brown proper exciple becomes more obvious and the lirellae can then appear reddish brown (Archer 1999b: 283).
