A revision is made of Australian taxa in the genera Usnea and Neuropogon. Keys and descriptions for the 44 taxa of Usnea and the 2 species of Neuropogon are given.

Five new Usnea species are described: U. alboverrucata, U. effusa, U. oncodeoides, U. punctulata and U. subalpina. Two new varieties are described: U. bicolorata var. australiensis and U. hossei var. protocetrarica and three former species have been reduced to varietal status: U. hossei var. squarrosa, U. torulosa var. aurescens and U. rubicunda var. spilota. U. arida and U. rubescens have been placed in synonymy with U. rubicunda var. spilota, and U. contexta and U. capillacea have been placed in synonymy with U. articulata.

The introductory material is relatively brief, providing an overview of history, morphology and chemistry. There are good illustrations and clear explanations of the structures which should allow the user to interpret the complex morphology of the Usnea thallus. However, I did wonder whether 'annular rings' was a tautological phrase. In contrast to such clarity is the use of the term 'capillaceous' without a den nition, in describing the branches in Neuropogon. One topic that perhaps should have been included was some comment on subgeneric classification in the genus and the characterisation of the various species groups that are recognised in the revision and by other specialists in the genus. For instance, the subgenus Eumitria is mentioned, but its distinguishing character (a hollow axis) is only inferred from the section on morphology.

The systematic account is preceded by a key to the species. This is in principle a commendable key since, in every couplet except one, there is a morphological character or simple chemical test to enable identification. Although secondary metabolises are cited, these are not the exclusive means of identification. Another useful feature (which proved to be the key's undoing) is that the number of the preceding couplet leading to the one being considered is given, allowing the user to backtrack when a result may be questionable. Sadly, though, it became evident that the remaining couplets from 32 onwards are inaccessible, since 32 leads back to 27 but not vice versa. My guess is that a couplet is missing since this error could not be corrected by changing the numbers.

There follows the accounts of the thirty-seven species, five of which are described as new. Varieties are treated in six species, bringing the total number of taxa to forty-four. The species concepts seem to be relatively broad, preferring recognition of chemical variation at variety level, if at all. At times one is left uncertain whether the author is, in fact, treating some of the species as species groups or complexes, as comments that suggest this occur in the remarks that follow each species. For each species a description is given together with details of chemistry, distribution and habitat and specimens examined, although this is just for Australian material. The distribution maps cover a wider region and dots mark extralimital collections, but these are not cited in the text.

The author seems to have been strongly influenced in her account by the papers of KROG & SWINSCOW on East African species of Usnea. This can he seen in the number of species that occur both in Australia and East Africa. In fact, it now appears that a number of species are worldwide in distribution and while STEVENS has looked outside Australia for similar species, CLERC (1997) indicates that, for instance, the widely distributed U. hirta is closely related to, or even synonymous with, the Australian U. inermis. This was not picked up by STEVENS, although CLERC'S paper may have been published after the submission of her manuscript.

There are a number of glitches, the most unfortunate of which is the illegitimacy of the new species, U. punctulata, which is a later homonym of U. punctulata Stirt. (1883). Others are minor but avoidable. On the whole this is a useful work and will be of great value to Australasian lichenologists or even those further afield in the southern hemisphere.

J. C. David

Bibliography of Systematic Mycology and Index of Fungi