Flora of New Zealand Series

Thallus crustose, thin, evanescent. Photobiont absent or if present green, Trentepohlia. Ascocarps pseudothecia, dimidiate to flask-shaped with a carbonised clypeate wall. Paraphyses cellular, persistent, branched. Ascospores brown, ellipsoid to fusiform, 1-septate, one cell larger, often faintly warted, 8 per ascus.

Microthelia auct., included in the family Pleosporaceae contains c. 70 species of cosmopolitan distribution. Three corticolous species recorded from New Zealand [Müller Argoviensis Bull. Herb. Boissier 2, App. 1: 93-94 (1894)] are now referred to Anisomeridium and Arthopyrenia. A further four species are parasitic on other lichens and are not treated in this flora. At least two of these lichenicolous fungi described by Lauder Lindsay [ Trans. R. Soc. Edin. 24: 437-441 (1867)] as Microthelia are referable to other genera e.g., Lichenoconium Petr. et Syd. [Hawksworth Persoonia 9: 172-173 (1977)] and Endoccoccus Nyl. [Hawksworth Trans. Br. mycol. Soc. 67: 54 (1976); Bot. Notiser 132: 287 (1979)]. The genus is heterogeneous and still very poorly collected and understood in New Zealand. The generic name is illegitimate [see Hawksworth and Sherwood Taxon 30: 339-340 (1981)] and a revision of all taxa of the genus is currently in preparation. It is probable that most material of Microthelia auct., from New Zealand will be placed in Anisomeridium (see under that genus).