Polymeridium catapastum
=Verrucaria (Thelidium) suffusa C.Knight, Trans. N. Z. Inst. 15: 356 (1883).
≡Arthopyrenia suffusa (C.Knight) Müll.Arg., Bull. Herb. Boissier 2, App. 1: 89 (1894).
Verrucaria suffusa. Lectotype: New Zealand, sine loco [probably Wellington], 20.i.1882, C. Knight s.n. – BM [fide Galloway (1985a: 17)]. Isolectotypes – G, H-NYL 880, 881 (Harris 1993: 629).
Description : Thallus epiphloeodal, crustose, continuous to rimose, matt, smooth to minutely uneven, white to pale-grey, 20–40 μm thick, UV−, ecorticate, with or without a grey-black marginal prothallus. Perithecia black, semi-immersed, solitary, partly overgrown by thallus, 0.23–0.5 mm diam.; ostiole apical or slightly eccentric. Pseudoparaphyses inspersed with granules and oil droplets. Asci 8-spored, 100–115 × 17–21 μm. Ascospores 3-septate, colourless, oblong–ellipsoidal, 22–30(–33) × 6–9(–10) μm, with a gelatinous sheath 2–3 μm thick.
N: ?Wellington. Still very poorly collected and understood in New Zealand. It is a widespread tropical species known from the SE United States, the Caribbean, northern and central South America, Malaysia and Papua New Guinea (Harris 1986, 1993) and eastern Australia from Queensland to New South Wales (McCarthy 1995g: 15; 2003c; 2006).
Pantropical
Illustrations : Knight (1883: pl. XXXVI, fig. 12 – as Verrucaria suffusa); McCarthy (1995g: 17, fig. 1C).
Polymeridium catapastum is characterised by: the corticolous habit; the white or creamish to pale-grey ecorticate, UV− thallus; semi-immersed, solitary, partially overgrown perithecia; inspersed pseudoparaphyses; and 3-septate ascospores, 22–30(–33) × 6–9(–10) μm.
