This is the fifth monographic work in the series on the genera once
included in the family Opegraphaceae (see also Torrente & Egea, 1989
and Egea & Torrente, 1994) and currently referred to the family
Roccellaceae (see also Sparrius, 2004 and Erz et al., 2005).
In this volume the author evaluates the tropical species from Africa,
South-East Asia and Australasia included in the genus Opegrapha based
on morphological and chemical characters. Sadly, the treatment is only
traditional, with six pages of text discussing the variations of
thallus, ascoma, conidioma and chemical characters. For a more modern
approach, using molecular methods, we are referred to the author’s
collaborative paper in Erz et al. (2009), where it was shown that the
genus is polyphyletic and needs to be split into several
genera. However, none of those findings are reflected in this
treatment. There is no discussion, either, on the current systematic
placement of the genus and its relationship with other morphologically
very distinct genera in the Roccellaceae. Nevertheless, some specific
comparisons to confamilial genera are scattered in the entries under
headings of Excipulum (p. 10), Hymenium and hypothecium (p. 11), Asci
(pp. 11-12) and Ascospores (pp. 12-13).
In the traditional sense Opegrapha, together with the related
Arthonia, is one of the most species-rich genera in the order, with
over a thousand specific names once attributed to it, although only
around 360 species are recognised in the latest edition of the
Dictionary of the Fungi (Kirk et al., 2008). In the current work, the
author treats 105 species epithets and, of these, only 45 species are
accepted in the genus. However, eight of the species are new to
science, mostly as a result of the collecting trips undertaken by the
author to the central African countries of Benin, Gabon, Rwanda,
Zambia and La Réunion. These fresh collections were supplemented with
types and other unnamed material from various countries found in
national and private herbaria, e.g. material from Thailand kept at
BM. The author includes five keys to enable separation of the species,
which have been compiled on the basis of ascospore septation: a very
practical approach, though difficult to apply if the material is old
or in poor condition.
Following other monographic treatments, the species are discussed in
alphabetical order, including synonymy, detailed descriptions,
chemistry, distribution and ecology, observations, and figures (124 in
total), comprising black and white habitus photographs, ascus and
ascospore drawings, and species distribution maps. In addition to the
31 species listed as synonyms, six belong to other genera pertaining
to the same order, e.g. Arthonia (Arthoniaceae), Enterographa and
Lecanographa (Roccellaceae), and to the order Patellariales:
i.e. Patellaria stirtonii, and new combinations are proposed for
them. Nine other species are excluded from the genus mostly on the
grounds of the types being in poor condition. Despite some of my
above misgivings regarding the lack of systematic input and
comparisons to similar genera which would have helped beginners, this
work is a much-needed descriptive contribution to the tropical species
in genus, and follows in the footsteps of the work undertaken by
Redinger during the first half of the 20th century.
Begoña Aguirre-Hudson
Bibliography of Systematic Mycology, 12(9), April 2010