Traditional classification concepts in lichenology are often, but not always, supported by molecular results. Molecular data should be compared and correlated with micro-morphological and ultrastructural information before systematic rearrangements are undertaken. Visualization of the distribution of morphological and other characters in specified groups is considered as a desirable result per se, but it is also important to discover whether correlating characters are dependent on each other or not; and if not, whether their distribution in a group might support existing classification concepts. A data set for lecanoralean and other lichenized and lichenicolous genera, comprising 90-mostly multi-statecharacters was used to store morphological, chemical and ecological data, and to test character correlations. Several examples of such analyses are presented. The following pairs of characters show some degree of dependence: ascospore septation and number per ascus, ascospore wall type and pigmentation, ascospore and epihymenium pigmentation. Several authors postulated that ascus types are good phylogenetic markers. Ascus types have been widely used for classification concepts of the Lecanorales. Two-dimensional correlation queries of ascus types with the following morphologcal characters were made: substratum preference, thallus growth form and ascospore septation. These correlations supply characteristic profiles for the various ascus types, which have to be compared with forthcoming phylogenetic hypotheses based on molecular data.C 1998 The British Lichen Society

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.

Lichen communities were studied using the Uppsala system and the Domin scale. The Conizaeoidion (comprising the union Lecanoretum pityreae), the Lecanorion dispersae, nom. nov. (comprising the union Lecanoretum dispersae) and the Xanthorion (comprising the unions Caloplacetum heppianae and the Physdetum caesiae) occur in London today. The survival of the Caloplacetum heppianae is apparently threatened in places by the presence of the mite Ameronothrus maculatus. Effective lichen conservation in London requires a reduction in sulphur dioxide emission and the conservation of surviving semi-natural vegetation, important old limestone churchyard memorials, and old walls. A brief history of lichen study in the Area is given, and in the Flora Lecania erysibe forma sorediata is described as new to science and Verrucaria viridula forma tectorum is a new combination.

The lichen genus Chrysothrix Mont, is shown to comprise four species: C. candelaris (L.) Laundon comb, nov., C. chlorina (Ach.) Laundon comb, nov., C. chrysophthalma (P. James) P. James & Laundon comb, nov., and C. pavonii (Fr.) Laundon comb. nov. (C. noli-tangere (Mont.) Mont.). The genera Pulveraria Ach. and Temnospora Massal. are placed in the synonymy of Chrysothrix nom. cons., and all bright yellow, leprose, sterile lichens with pulvinic acid derivatives, formerly included in Lepraria and Crocynia, are referred to the genus. Chrysothrix oceanica Rasanen is excluded; it probably belongs to Caloplaca. A key to and detailed accounts of the recognized species are included. There are three chemotypes of Chrysothrix candelaris, one of which is probably of hybrid origin.

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