Flora of New Zealand Series

Description : Thallus areolate, in spreading patches, 5–10(–25) mm diam., often coalescing into much larger composite colonies. Prothallus distinct, black, at margins and between areolae. Areolae contiguous, 0.5–1.5 mm diam., mostly crescent-shaped, each segment partly to entirely surrounding an apothecium, to angular or orbicular with or without a central apothecium; flat to subconvex, smooth, bright-yellow to greenish yellow, epruinose. Apothecia frequent, rounded, 0.1–1 mm diam., plane to subconvex. Proper exciple persistent but indistinct, concolorous with disc. Epithecium pale red-brown, 7–15 μm thick. Hymenium pale greenish blue, 100–115 μm tall. Hypothecium intense dark-brown, opaque. Asci globose, 8-spored, 75–85 × 35–45 μm. Ascospores ellipsoidal to somewhat curved, submuriform, slightly constricted at septa, with 8–24 (–28) cells in optical section, colourless at first soon becoming dark-greenish to brown-black, 27–45 × 11–19 μm.

Chemistry : Thallus and medulla K+ yellow, C+ red or −, Pd+ orange, I+ blue; containing rhizocarpic and stictic acids, and occasionally also gyrophoric acid.

N: Wellington (Taranaki Falls, Mt Ruapehu). S: Canterbury (Waimakariri old riverbeds, Hakataramea Valley), Southland (S Mavora Lake). On dry, exposed, sunny rock outcrops in grassland. Associating with Buellia dunedina, B. stellulata, Candelariella vitellina, Diploschistes gyrophoricus, Immersaria athroocarpa, Lecanora rupicola, Lecidea fuscoatrula, Rhizocarpon geographicum, R. grande, R. submodestum and brown and yellow species of Xanthoparmelia. Known also from Great Britain, Europe, Scandinavia, the high-Arctic, Turkey, and North America (Thomson 1968a; Feuerer 1978; Purvis et al. 1992; Nimis 1993; Santesson 1993; Esslinger & Egan 1995; Wirth 1995a, 1995b; John 1996; Diederich & Sérusiaux 2000; Scholz 2000; Hafellner & Türk 2001; Llimona & Hladun 2001; Coppins 2002b; Nimis & Martellos 2003; Santesson et al. 2004).

Bipolar

Illustrations : Runemark (1956a: 23, fig. 7D; 24, fig. 8F; 95, fig. 33A, B; 99, fig. 37A); Feuerer (1978: 90, 91); Jahns (1980: 201, pl. 461); Foucard (1990: pl. 281); Dobson (1992: 298; 2000: 342; 2005: 388); Wirth (1995a: 535, pl. 55A; 1995b: 805A, 815); Clayden (1998: 698, figs 1–9; 688, figs 10–17; 698, figs 18–26; 690, figs 27–33); Brodo et al. (2001: 636, pl. 776).

Rhizocarpon lecanorinum is characterised by: the yellow, crescent-shaped areolae, often enclosing prominent apothecia; a red-brown epithecium; a pale greenish blue hymenium; 8-spored asci; and colourless to greenish or brown-black, submuriform ascospores. It is chemically distinct from R. geographicum, containing stictic acid (K+ yellow, Pd+ orange), rather than psoromic acid (K−, Pd+ yellow).