Flora of New Zealand Series

≡Catillaria hochstetteri Körb., Parerga Lich.: 195 (1861).

Description : Thallus grey-brown to red-brown, areolate, 0.1– 0.35 mm thick. Areolae flat to subconvex, 0.2–1 mm diam. Apothecia frequent, black, lecideine, flat to subconvex, 0.6–1 (–1.2) mm diam., sessile when well-developed, or innate among areolae, proper exciple persistent, often poorly formed. Epithecium usually with blue-black pigmentation (macrocarpa -green; K−, N+ red), rarely only brown pigmentation present. Hymenium colourless, I+ blue, 95–150 μm tall. Hypothecium dark-brown. Asci 85–100 × 30–35 μm. Ascospores hyaline becoming brown when over-mature, halonate, 1-septate, 21–25(–28) × (8.5–)10–12 μm.

Chemistry : Thallus K− or + yellow, C−, Pd− or + orange; with or without stictic acid (Fryday 2002b: 452). New Zealand collections are stictic-acid-deficient (Fryday 2000a: 38).

S: Canterbury (Arthur's Pass), Southland (E portal of Homer Tunnel). On rocks in subalpine scrub (Fryday 2000a: 38; 2002b: 458). Known also from Great Britain, Europe, Scandinavia, Svalbard, the Ukraine, and North America (Lynge 1932; Thomson 1968a, 1979; Feuerer 1978; Purvis et al. 1992; Nimis 1993; Santesson 1993; Esslinger & Egan 1995; Wirth 1995a; Kondratyuk et al. 1996a; Elvebakk & Hertel 1997; Diederich & Sérusiaux 2000; Scholz 2000; Hafellner & Türk 2001; Llimona & Hladun 2001; Coppins 2002b; Nimis & Martellos 2003; Santesson et al. 2004).

Bipolar

Illustrations : Feuerer (1978: 89); Foucard (1990: 243); Wirth (1995a: 535, pl. 55L); Dobson (2000: 341; 2005: 387); Brodo et al. (2001: 636, pl. 775); Fryday (2002b: 453, fig. 1).

Rhizocarpon hochstetteri is characterised by: the areolate, grey-brown to red-brown thallus; a blue-black epithecium; and halonate, 1-septate ascospores that are hyaline at first, becoming brown when over-mature, 21–25 (–28) × (8.5–)10– 12 μm. Recent molecular results (Ihlen & Ekman 2002) show that R. hochstetteri is more closely related to Poeltinula than it is to other species of Rhizocarpon, and that Rhizocarpon as a monophyletic group might be upheld if R. hochstetteri was excluded from the genus. They suggest a detailed comparative study of the morphology and ontogeny of R. hochstetteri and of currently accepted species of Poeltinula, in order to clarify their taxonomic position (cf. R. oxydatum).