Verrucaria subdiscreta
Description : Thallus crustose, epilithic, olive-green to green-black (dull-green in shade), subgelatinous and ±translucent when moist, (20–)40–60 μm thick, forming colonies 3–5 cm diam., usually areolate, occasionally rimose, rarely effuse to continuous, dotted with carbonaceous puncticulae, 15–30 μm wide. Areolae angular, regular or irregular, deeply divided, exposing substratum between areolae, matt, smooth, plane to subconcave or subconvex, 0.1–0.35 mm wide. Perithecia compound, semi-immersed to ±superficial, numerous, usually solitary, or in groups of 2 or 3. Involucrellum 0.12–0.22 mm diam., matt or glossy black, extending to exciple-base level, either contiguous with exciple or arching away from it, 30–40(–60) m thick; apex usually rounded. Ostiole inconspicuous to slightly depressed. Exciple pale- to dark-brown, 10–15 μm thick. Centrum globose to ±obpyriform, 0.08–0.15 mm diam. Periphyses 10–18 × 1.5–2.5 μm. Asci clavate, 25–35 × 10–14 μm. Hymenial gel and ascoplasm I−. Ascospores ellipsoidal to elongate-ellipsoidal, 8.8–14.8 × 3.8–6.4 μm. Pycnidia numerous, semi-immersed, 40–60(–80) μm diam., with a black exposed surface depressed at ostiole. Conidia bacillar, 2–3 × 0.5 μm.
S:?? On seashore rocks at or above high tide mark. Known also from Australia, Tasmania and Macquarie I. (McCarthy 1991b: 329–330; 2001j: 194; 2003c).
Australasian
Illustrations : McCarthy (1991b: 328, fig. 6; 2001j: 180, fig. 52)
Verrucaria subdiscreta is characterised by: the coastal rock habit; its thin, areolate thallus; carbonaceous puncticulae; small, prominent perithecia; and small rather than minute ascospores (McCarthy 1991b: 329).
