a1 Department of Botany, British Museum (Natural History), Cromwell Road, London SW7 5BD, UK.
The Lepraria membranacea group is shown to constitute the genus Leproloma Nyl. ex Crombie, characterized by the presence of dibenzofurans. A full account of the genus and four species is given: L. angardianum (Øvstedal) Laundon comb, nov., L. diffusum Laundon sp. nov., L. membranaceum (Dickson) Vainio, and L. vouauxii (Hue) Laundon comb. nov. The species L. diffusum comprises var. diffusum and var. chrysodetoides Laundon var. nov. Fertile material of L. membranaceum was found in the 18th century; the morphology and chemistry of this suggests that the genus may tentatively be included in the ascomycete family Pannariaceae. Leproloma angardianum has a powdery thallus in shade but a granular thallus in sun. Lepraria arctica is a synonym of Leproloma vouauxii. The latter species contains a newly identified compound, methyl pannaric acid, and L. diffusum also contains a new compound, oxypannaric acid.
(Accepted May 14 1988)