Aspicilia calcarea
≡Lichen calcareus L. Sp. Pl. : 1140 (1753).
Description : Thallus rather thick, forming extensive patches to 30 cm diam. or more, continuous to areolate; areolae radially orientated in outer parts of thallus, chalky to grey-white, delimited by a marginal, zonate, grey prothallus. Apothecia innate, round or angular, 0.2–1 mm diam., disc black, epruinose or slightly white-pruinose; thalline margin present, slightly raised. Asci 4-spored. Ascospores broadly ellipsoidal to subglobose, 18–30 × 14–27 μm.
S: Canterbury (Nape Nape). On limestone, maritime rocks. Still very poorly collected and understood here. Known also from Great Britain, Europe, Scandinavia, North America and Australia (Purvis et al. 1992; Nimis 1993; Santesson 1993; Esslinger & Egan 1995; McCarthy 2003c; Nimis & Martellos 2003; Santesson et al. 2004).
Cosmopolitan
Illustrations : Galløe (1936: p. 8, pls 11–14); Weber (1967: 46, figs 1–4); Ozenda & Clauzade (1970: 558, fig. 462); Moberg & Holmåsen (1982: 110); Phillips (1987: 168); Foucard (1990: pl. 26); Wirth (1995a: 136, fig. 23F; 1995b: 149); Eldridge & Tozer (1997: 35, fig. 4.13); Dobson (2000: 65; 2005: 73).
Aspicilia calcarea is characterised by: the saxicolous (basicolous) habit; the chalky to grey-white, rather thick, areolate cracked thallus, delimited by a marginal, grey, zonate prothallus; immersed apothecia; 4-spored asci; and broadly ellipsoidal to subglobose ascospores, 18–30 × 14–27 μm.
