Flora of New Zealand Series

Thallus crustose, epi- or endophloeodal, whitish, greyish, pale greenish-olive, yellow-olive to ochraceous, sometimes spotted with pigmentation, shining or matt, some species with scattered, minute, maculae (×10 lens), ± effigurate, often delimited by a thin black, irregular prothallus. Photobiont green, Trentepohlia. Ascocarps scattered or crowded, solitary or 2-3-confluent, immersed to ± emergent, globose, subglobose or ± flattened, ascocarp wall composed of an outer, generally carbonised involucrellum and an inner brownish exciple, some species columellate. Ostiole apical, vertical, to marginal and ± horizontal, depressed to papillate. Interthecial hyphae persistent, not or rarely branched, not anastomosing, 1-2 µm thick, septate. Asci cylindrical-clavate to clavate, bitunicate. Ascospores becoming ± brown, 3-septate (rarely to 7-septate), thick walled, oblong-ellipsoid, biseriate, rarely uniseriate, 8 per ascus.

Pyrenula is a widespread, pantropical to pantemperate genus of c.. 200 species, most of which are confined to tropical rain forests. Many species contain varying amounts of several xanthones (fluorescing yellow, gold or orange in UV) which may in some cases be of importance in species identification. Hawksworth and Sherwood [ Taxon 30: 346-347 (1981)] discuss typification of the genus.

Nineteenth century records show 17 taxa in Pyrenula to be present in New Zealand, described mainly by Knight, who had an early, and informed interest in the genus, and by Stirton, and Nylander. Zahlbruckner [ Denkschr. Akad. Wiss. Wien math.-naturwiss. Kl. 104: 255-256 (1941)] described a further three species, but his names appear to be synonyms of existing taxa. The names of predominantly Northern Hemisphere species (P. bonplandiae, P. kunthii, P. laevigata (syn. P. glabrata), P. nitida and P. nitidella) have, at various times, been applied to New Zealand material; in this account these are eschewed in favour of names described from New Zealand collections, since it is not yet known whether the species of Pyrenula found in New Zealand are identical with these northern species. Until more is known of the relationships of New Zealand and tropical populations, it is thought convenient to keep the New Zealand names separate as a basis for future work, when the true affinities of the New Zealand species will undoubtedly be clarified. The present account discusses 10 species, but it is in no sense a revision of Pyrenula in New Zealand, rather it is an appraisal of the names (based on a study of their types) available in the literature, with little examination of recently collected material.