Verrucaria tessellatula
Description : Thallus even, tessellate-areolate, 0.15–0.20 mm thick, matt, pale buff-brown; areolae angular, 0.5–1.0 mm diam., separated by conspicuous black cracks, 0.15 mm wide. Perithecia immersed, numerous, 1–6 per areole, 0.1–0.2 mm diam. Involucrellum black, convex, rising slightly above thallus level, matt or slightly glossy, not impressed or papillate; in section brown-black forming a dome-like roof over upper part of exciple. Ostiole minute. Exciple colourless. Centrum globose 165–180 μm diam. Ascospores 10–15 × 6.5–9.0 μm.
S: Southland (Breaksea Sound). Known also from Kerguelen (type locality), the Falkland Is, Tierra del Fuego, South Orkney Is, South Shetland Is, South Georgia, Marion and Prince Edward Is, Bouvetøya and Maquarie I. (Lamb 1948a; Redón 1985; Øvstedal 1986: 54–55; McCarthy 1991d, 1992; Øvstedal & Gremmen 2001; Øvstedal & Lewis Smith 2001: 361; McCarthy 2003c, 2006; Søchting et al. 2004).
Austral
Illustrations : Darbishire (1912: pl. 3, fig. 34 – as Verrucaria glaucoplacoides); Lamb (1948a: 14, fig. 3D).
Verrucaria tessellatula is a marine species of the spray zone, associating with V. maura on coastal rocks 0.5–1.0 m above high tide level. It has a pale buff-brown, rimose to areolate thallus with black-walled rimae. The immersed perithecia, 0.1–0.2 mm diam., have a black apical involucrellum, a colourless exciple, and ascospores 10–15 × 6.5–9 μm. For differences between V. tessellatula and the related buff-brown species V. bubalina and V. durietzii see above under those taxa.
