Flora of New Zealand Series

≡Acolium ocellatum Körb., Parerga Lich.: 285 (1861).

Description : Thallus crustose, well-developed, with flattened, subcrenulate verrucae or subareolate, grey. Isidia ±frequent, globose, forming irregular, well-delimited blue- or brown-black, ±soralia-like clusters or patches. Apothecia immersed, not seen in New Zealand material. Ascospores 1-septate, 22–28 × 12–15 μm.

Chemistry : Cortex K−, C−, KC− Pd−; medulla I+ dark blue; containing usnic acid, epanorin and rhizocarpic acid (Tibell 1976: 240).

N: Northland (Puketi State Forest), Taranaki (Kaitoke Ra.). On lignum (fenceposts, gates) in open farmland, often in nutrient-enriched habitats. Widely distributed in Eurasia and North America (Tibell 1976, 1994; McCune & Rosentreter 1995; Nimis & Martellos 2003; Tibell & Ryan 2004g) in moderately mesic cool-temperate to warm-temperate areas. The occurrence in New Zealand is probably a recent accidental introduction by man (Tibell 1994: 195).

?Bipolar

Illustrations : Tibell (1976: 241, fig. 11); Wirth (1995b: 903).

Thelomma ocellatum is characterised by: the lignicolous habit; the warted, verrucose, subareolate thallus; globose isidia in soralia-like clusters; and a chemistry of usnic acid, epanorin and rhizocarpic acid.