The generic concepts in the graphideoid lichens have traditionally
been based on the Saccardo spore groups. This has long been recognized
as unsatisfactory, not least because more fundamental differences in
exciple structure particularly were available for use. However, most
lichenologists have been deterred from addressing the problem because
of the shear numbers of taxa involved, encompassing some 78 generic
names and around 1000 species.
Bettina Staiger, already known for her careful revision of Haematomma
(Staiger & Kalb 1995), has risen to the task. Here she addresses the
application of all pertinent generic names, and examined around 1000
collections representing 175 species. Nineteen genera are accepted,
seventeen formerly described before (but mainly hidden in the synonymy
of spore-based genera) and two proposed as new (Carbacanthographis and
Platythecium). A major obstacle to progress in the group had been the
number of generic names that were previously untypified; 11 generic
names are typified here to resolve this issue. The characters used are
mainly based on the structure and location of the excipular and
hypothecial tissues, supplemented by iodine reactions of the
ascospores, and also ascospore colour (but not so much
septation). Many of the names now used will be unfamiliar, and where
well-known names are accepted this is with revised
circumscriptions. Graphis, Phaeographis and Sarcographa remain, and
Phaeographina is kept for the moment just for its type
species. Graphina becomes a synonym of Ustalia, the former name not
being proposed for conservation as only a few species formerly placed
there remain. I was amused to see that Phaeographis still needed to be
conserved against several older synonyms, having been involved in
proposing this over 20 years ago (Hawksworth & Sherwood 1981)! Four
generic names are categorized as 'nomina dubia et rejicienda'; formal
rejection, however, requires Committee action under the Code, and it
could be prudent to make such proposals to preclude all risks of their
resurrection.
The system now proposed needs to be tested, and where possible
vindicated, by molecular data. The author carried out a little
molecular work as a part of this investigation using LSU rDNA which
suggested the studies were on the right lines, but as only 11 species
were sequenced the results must be treated as preliminary.
The line drawings and photographs are certainly the best yet to have
been prepared of these lichens. These, taken with the extended English
summary and English versions of the detailed overall key and the keys
to species within each genus, will ensure the accessibility of the
work to those who do not read German. The author deserves our
congratulations on a job well-done, and after the dust settles over
the old concepts and numbers of name changes, the work is sure to be
regarded as one of the classic lichen revisions.
Dr. David L.Hawksworth
Mycotaxon vol. 86
