var. citrinella
Description : Thallus irregularly spreading, 0.5–2(–3) cm diam., granular-sorediate, granules 100 μm diam., or less, vivid yellow-green, terricolous. Apothecia rare, black, sessile, solitary to 2–4(–6)-confluent, 0.1–2 mm diam., round to irregular, projecting from thalline granules, disc matt, epruinose, roughened, plicate-rugose at maturity. Epithecium densely granular, greenish black, colour dissolving in K, 25–36.5 μm thick. Hymenium 105–125 μm tall, pale straw-coloured to pale grey-brown, opaque, appearing somewhat granular. Asci narrowly clavate, tapering at foot 112–140 × 8– 11 μm. Ascospores colourless, tapering at ends, acicular, 7–12(–18)-septate, (65–)70–85(–105) × 2.5–3.5 μm.
Chemistry : Rhizocarpic acid, epanorin, unidentified pigments and atranorin (Obermayer 1994).
N: South Auckland (Upper Kauaeranga Gorge), Wellington (Ruahine Ra.). S: Nelson (Mt Arthur Ra., Lookout Ra., Kakapo Peak, Mt. Peel, Mt Benson, Lonely Lake, Dun Mountain, St Arnaud Ra.), Marlborough (Branch River), Canterbury (Mt Faust, Arthur's Pass, Cass, Craigieburn Ra., Upper Rakaia, Upper Ashburton, Governor's Bush and Mt Sebastopol, Mt Cook National Park, Kirkliston Ra.), Otago (Humboldt Mts, Hector Mts, Makarora, Coronet Peak, Old Man Ra., Rock & Pillar Ra., Lammerlaw Ra., Swampy Hill, Dunedin). On exposed alpine soil in tussock grassland and subalpine scrub, on solifluction slopes, sheltered rock faces, and soil-filled crevices and gutters in boulder fields. It colonises rather drier sites than A. alpina and has an altitudinal range of 540–1950 m. Widely distributed in the Northern Hemisphere where it is a circumpolar, arctic-alpine species (Obermayer 1994; Hansen & Obermayer 1999; Nimis & Martellos 2003). In the Southern Hemisphere it has a rather restricted distribution being known from Tasmania (Kantvilas 1996), New South Wales (Filson 1996; McCarthy 2003c), Patagonia, Marion I. in the Indian Ocean and from South Georgia, South Orkney Is, South Shetland Is, Charcot I., and the Antarctic Peninsula (Galloway & Bartlett 1986: 399, fig. 4; Convey et al. 2000; Øvstedal & Gremmen 2001; Øvstedal & Lewis Smith 2001).
Bipolar
Arthrorhaphis citrinella var. citrinella is characterised by: having no calicum oxalate crystals in the medulla, by the thick marginate to immarginate apothecia with a rough disc, and the long, acicular ascospores which lie at the same height in the ascus. Sorediate specimens may be difficult to distinguish from A. alpina (Obermayer 1996).
