Verrucaria dufourii
Description : Thallus ±immersed, continuous, rimose, rarely areolate, smooth or uneven, occasionally with shallow pits, grey, grey-green, grey-brown or indistinct, often delimited by a dark-brown line of prothallus, or a groove. Perithecia compound, ⅓–½ immersed; apex flat or excavate. Involucrellum black, 0.3–0.6 mm diam., dimidiate or extending to exciple-base level. Centrum 0.2–0.4 mm diam. Exciple colourless to pale-brown, rarely dark-brown. Ascospores 12–23 × 6–10 μm.
S: ?Canterbury, ?Otago. On maritime limestone. Known also from western Eurasia and Tasmania (McCarthy 2001j: 182, 2003c).
Cosmopolitan
Illustrations : Zschacke (1934: 117, fig. 44); Ozenda & Clauzade (1970: 149, fig. 104); Wirth (1987: 497; 1995b: 961); Dobson (1992: 356; 2000: 406; 2005: 455); McCarthy (2001j: 180, fig. 50).
Verrucaria dufourii is characterised by: the basicolous (limestone) habit; an endolithic thallus and moderately large and prominent perithecia, commonly with a concave to deeply excavate apex; colourless to pale-brown exciple and ascospores, 12–23 × 6–10 μm.
