Flora of New Zealand Series

Thallus endophloeodal indicated by discolouration of the substrate, usually whitish or greyish, rarely darker, in a few species consisting of an epiphloeodal, dark brown subicular layer of hyphae, or epilithic in a single species. Photobiont when present green, Trentepohlia or blue-green. Perithecia with a brown to blackish wall, usually lacking below. Ostiole erect or rarely eccentric. Paraphyses thick and irregular with short cells, often appearing almost parenchyma-like to slender and regular with relatively long cells, sometimes partially gelatinised, rarely completely so. Asci various, ovate to narrowly ovate, narrowly elliptical, obovate or cylindrical, tip often thickened, with or without an obvious ocular chamber. Ascospores typically 8 per ascus, often fewer, rarely 2-4 per ascus, colourless, oval-ellipsoid, mostly 1-3-septate (to 7-septate), constricted at septa, spore wall ornamented in some species at maturity, perispore usually evident, often well developed.

Arthopyrenia is a cosmopolitan genus of c. 270 species, most of which are corticolous. It is included in the family Pleosporaceae. North American species are treated by Harris ["A taxonomic revision of the genus Arthopyrenia Massal., sens. lat. (Ascomycetes) in North America". Xerox University Microfilms, Ann Arbor, Michigan 48106, 288pp. (1975)], and his account contains the most modern assessment of the genus. Useful information is also given in Swinscow [ Lichenologist 3: 152-166 (1965)]. Littoral species are discussed by Santesson [ Ark. Bot. 29A(10): 1-67 (1939)]. Eight species are recorded here, but the genus is very poorly known and collected in New Zealand, with few modern collections to supplement those of Knight and Buchanan from last century.

A. fossularia (Stirton) Müll. Arg. [Basionym: Verrucaria fossularia Stirton , Proc. phil. Soc. Glasg. 10: 303 (1877)] is a lichenicolous fungus and is not treated in this account.