The serial Bibliotheca Lichenologica has, over the years, been an
important publisher of major works on lichen systematics and the
present volume is no exception. At a time when funding for primary
taxonomic studies is scarce and journals that will publish substantial
monographs are few and far between, it is reassuring to see the
tradition continuing and such works still appearing.
The subject of this monograph is a genus of crustose, corticolous and
saxicolous lichens that occur worldwide, the species of which are, for
various reasons, notoriously difficult to identify. The last major contribution
on this genus was published in 1980 and covered North America. The
present work is also geographically defined, although in "Australia" the
author includes the adjacent territories of the Norfolk and Lord Howe and
Macquarie Islands, as well as Papua New Guinea. An account is provided of
128 species, of which 20 are new to science. It is also very much a collation
of the author's previous extensive work on Pertusaria. The introductory part
includes sections on the history, morphology, distribution and chemistry of
the genus. The latter section is detailed and complex, but merited, as
chemistry is so important for recognising the species, since many do not
produce ascomata, only vegetative propagules (isidia, soredia).
The systematic part is arranged according to the subgeneric classification
proposed by ARCHER (1993) [Bibliotheca Lichenologica 53: 1-171 and now
enhanced by chemical characters. Keys to species are provided at the
beginning of each subgenus or section. As with the parmelioid genera and
species, the characterisation of lichen metabolises using thin layer and liquid
chromatography is essential if an identification to species level is to be
achieved. Regrettably, this will inevitably limit the use of this monograph to
the better equipped laboratories, since couplets such as "Planaic acid
present, or 2,2'-Di-O-methylstenosporic acid present" are useless to the
field-based lichenologist. This might be a minor issue if only a few of the
couplets depended solely on the presence or absence of specific compounds
but. for instance, the keys to the species in subgenus Pertusaria contain 96
couplets of which 47 depend on knowing precisely the compounds present
in the thallus. Is it really the case that no other characters could be found
which would identify the species?
The species accounts comprise typification information, description,
chemistry, published illustrations, distribution and ecology and details of
specimens examined. There are maps to supplement the text on distribution
and black-and-white close-up photographs of the thalli of some species. A
final paragraph contains useful comments about the species, often
mentioning distinguishing features and closely related species. There is a
small section on excluded species followed by references and various
indexes: taxonomic, chemical, figures, tables and distribution maps.
It was disappointing that there was no mention of evolution, especially
since the author's clear mastery of the chemical data and biosynthetic
pathways would surely have led to some conclusions as to how the species
arose. Further. the brief section on distribution reflected the biogeographic
patterns of the species and these data can be helpful in determining possible
phylogenies as well.
Overall, this is a worthy opus, a valuable collation of current knowledge
of the genus and bound to be an important reference on Pertusaria not just
in Australia but more broadly in the southern hemisphere and palaeotropics
as a whole.
Bibliography of Systematic Mycology (BSM) and Index of Fungi (IF)
