Arthrorhaphis citrinella (Ach.) Poelt
Lichen citrinellus Ach., K. Vet.-Akad. nya Handl. 1795: 135 (1795).
Thallus crustose, squamulose, squamules bullate, convex more than 1 mm diam., bright lime-green to yellowish-green, ± areolate, with black, irregular cracks between humped irregular areolae, often dissolved in soredia, thalli to 1.5 cm diam. Soredia granular-farinose, bright yellow-green. Apothecia black, flat, with a prominent black margin, disc black, matt, epruinose. Ascospores 8-10(-12) septate, 35-60 µm long. Chemistry: Rhizocarpic acid.
N: Kaimanawa Ra., Ruahine Ra. and Tararua Ra.; S: St Arnaud Ra. southwards to Fiordland mountains. St: Mt Anglem and Fraser Peaks, Port Pegasus.
Bipolar
A widespread high-alpine species easily recognised by its vivid yellow-green colour. It is often found in mats of Andreaea on rock crevices, or on soil, in which habitat it is often sterile and sorediate. New Zealand plants agree well with A. citrinella var. alpina (Schaer.) Poelt , Bestimmungsschl. eur. Flecht.: 126 (1969).
