Flora of New Zealand Series

Thallus crustose, ± areolate, areolae sometimes raised at margins, appearing subsquamulose, without isidia or soredia, saxicolous. Photobiont green. Apothecia lecanorine, often punctiform, sunken at first, then sessile, flat, 1-6 per areola. Paraphyses swollen or moniliform at apices. Ascospores very minute, colourless, simple, subglobose to ellipsoid, more than 100 per ascus.

Acarospora is a cosmopolitan genus of c. 200 species included in the family Acarosporaceae [Poelt, in Ahmadjian and Hale (Eds) "The Lichens" pp. 623-624 (1974)] and monographed by Magnusson [ K. Sv. Vet. -Akad. Handl. ser. 3, 7 (4): 1-400 (1929); Annls cryptog. exot. 6: 13-48 (1933); Göteborgs K. Vetensk. o. Vitterh. Samh. Handl. 6 Folj. ser. B, 6 (17): 1-34 (1956)] who also described two species from New Zealand from the collections of G. Einar and Greta Du Rietz [ Sv. Bot. Tidskr. 37: 277-286 (1943)]. Weber [ Lichenologist 4: 16-31 (1968)] claims that many of Magnusson's taxa in subgen. Xanthothallia are synonyms. He discusses the effects of environmental modification on the morphology of species of Acarospora [ Sv. Bot. Tidskr. 56: 293-333 (1962)], and in a more general context dealing also with other lichen genera [in Seaward (Ed.) "Lichen Ecology" pp. 9-29 (1977)]. The genus is still very poorly collected and studied in New Zealand. Four species are recorded here but it is expected that additional taxa will be found in drier, alpine areas particularly east of the Main Divide in South I.