Flora of New Zealand Series

Thallus crustose, ± smooth and rimose or areolate to granular-verrucose, whitish or straw-coloured, effuse or bordered by a dark prothalline line, thalline hyphae I-. Photobiont green ? Trebouxia, cells globose c. 9-17 µm diam., Apothecia Lecideine, small to medium, marginate, disc concave to plane, rarely convex, pallid to black, sometimes faintly pruinose. Hymenium rather shallow, c. 40-50 µm tall, I+. Epithecium straw-coloured to dark brown often minutely granular, granules dissolving in K. Asci clavate-cylindrical, lecanoralean with amyloid tholus, 8-spored. Ascopores hyaline, smooth, mostly 1-septate. Paraphyses numerous, mostly simple, apices incrassate, clavate or capitate, sometimes pigmented. Hypothecium (Incl. subhymenium) hyaline, I-. Excipulum well-developed, without algae, ± hyaline but appearing straw-coloured through densely interspersed, minute granules dissolving in K, of densely branched hyphae c. 1.7-2 µm diam. (in K). Pycnidia numerous, rather large and conspicuous, stromatic wall dark purplish-brown (K+ purple intensifying) above, becoming thinner and ± hyaline below, internally convoluted into c. 2-8 locules, locules criss-crossed by a few branched hyphae. Conidiogenous cells hyaline, cylindrical phialidic, often proliferating. Conidia hyaline, smooth, simple, ovoid to short-cylindrical.

Cliostomum, included in the family Lecideaceae, is a cosmopolitan genus of 2 described species formerly included in Catillaria. One species is known from New Zealand from one 19th century collection, but it is probably more widely distributed.