The genus Plectocarpon was established by the Strasbourg
pteridologist, cryptogamist, Professor of Botany, and cleric Antoine
Laurent Apollinaire Fée (1789-1874) In his celebrated Essai sur les
cryptogames des écorces exotiques officinales (Fee 1825). However, Fée
himself did not realise that it was a lichenicolous fungus, and
another 159 years passed before its true identity was recognised and
the generic name re-entered modern mycological systematics.
I still vividly remember my excitement in discovering Delise's
splendidly preserved specimens of "Sticta" in the Lenormand Herbarium
one golden October afternoon in 1982 in the Paris Herbarium
(PC-LENORMAND) when sheet after sheet proved to be type material of
names described by Delise in his monograph (Delise 1825a, 1825b) and
long thought to be lost in World War II when the city of Caen, where
they were originally lodged (see Degelius [1935]), was heavily bombed.
One of those was the type of Sticta delisea (Delise 1825a), which is
where the modern story of Plectocarpon begins. The type specimen
(Hawksworth & Galloway 1984, Galloway & James 1986) is a collection of
what is now known as Pseudocyphellaria glabra Infected with a
lichenicolous fungus forming apothecia-like galls on its upper
surface. When the Delise specimens which I had requested on loan
arrived at length in London at the BM, I showed that intriguing
specimen of P. glabra to David Hawksworth, and we agreed to
collaborate on material that had implications for Plectocarpon Fée,
for the Venus Lichenomyces Trevis. (Trevisan 1853), and also for the
typification of Delise's Sticta Relish (Hawksworth & Galloway 1984).
It is an interesting story.
Fée (1825) described the new genus Delisea (honouring his friend and
fellow cryptogamist Dominic Francois Delise [1780-1814], a
distinguished retired major of the French Army and Chevalier of the
Legion d'Honneur), on lichen material collected from King Island in
Bass Strait between Tasmania and Australia (the collection is
discussed in detail in Galloway & James [1986]). It differed from any
species of Dicta then known in the peculiar structure of what Fée
considered to be its apothecia. For the specific epithet of his new
genus, he chose pseudosticta (Fée 1825) and provided a colour
illustration of it (Fée 1825). However, Delisea Fée is a later
homonym of Delisea Lamouroux (Rhodophyta) published in 1819, so it had
to be rejected. He realised that, and in the "Additions et
Corrections" to the Essai (Fée 1825), he introduced Plectocarpon Fée
as a replacement for Delisea Fée, again discussing in some detail the
peculiar, apothecia-like structures. However, he did not combine the
epithet pseudosticta with Plectocarpon until his account of
Plectocarpon in the Dictionnaire Classique d'Histoire Naturelle (Fée
1828), an often overlooked compendium of cryptogamic information.
David Hawksworth and I erred in attributing the taxon Plectocarpon
pseudosticta (Fée) Fée to Fée's account in the Supplement to the Essai
(Fée 1837), and furthermore, in our account the date of publication of
the name Delisea pseudosticta Fée is erroneously given as 1925
instead of 1825! That error was subsequently rectified in Galloway &
James (1986), but unfortunately the mistake is still perpetuated in
the monograph reviewed here.
In the 20th century, the first accounts of a Plectocarpon-like fungus
were as Lecanora parasitica (Keissler 1930) and Rolf Santesson's
resurrection of Trevisan's genus Lichenomyces (Trevisan 1853) for a
parasite on Lobaria pulmonaria, which he identified as Lichenomyces
lichenum (Sommerf.) R. Sant. (Santesson 1960) in a paper which he wrote
on lichenicolous fungi from northern Spain. Hawksworth and I realized that
Lichenomyces and Plectocarpon were nonspecific, and mentioned that
Santesson had earlier intimated that an undescribed species also
occurred on Nephroma antarcticum from southern South America. That
implicated Plectocarpon as a co-evolved parasite on
Pseudocyphellaria, Lobaria, and Nephroma. Later, Galloway (1997)
mentioned Sticta caliginosa as being ". . . commonly infected with
Plectocarpon sp. ", underlining the association of Plectocarpon with
taxa in the Peltigerineae, families Lobariaceae and Nephromataceae
(Eriksson 2005). Santesson (1993) synonymised Epiphora Nyl. with
Plectocarpon, making two new combinations in the Genus, bringing the
known species to five, to which Diederich and Etayo (1994) added a
further five species from Northern Hemisphere collections. Aptroot et
al. (1997) described two new species from Papua New Guinea, Wedin &
Hafellner (1998) transferred Arthonia linitae into Plectocarpon, and a
new species was described from Canada and Russia (Ertz et al. 2003),
one from North America (Hafellner et al. 2002), and one from Chile
(Follmann & Werner 2003).
Today, 22 years after the modern resurrection of Plectocarpon as a
name for a Genus of lichenicolous fungi, we have a world monograph of
the genus authored by Damien Ertz, Claude Christnach, Mats Wedin, and
Paul Diederich, who bring together for the first time a view of the
genus expanded both taxonomically and geographically, with the great
riches of recent collections from the Southern Hemisphere (where the
genus is most speciose) at last adequately researched and documented.
The monograph accepts 32 species in Plectocarpon, 15 of them newly
described. The genus is well-represented and speciose in the cool
temperate Southern Hemisphere, with 10 species recorded from southern
South America and seven from Australasia. Flight species are known
from northern parts of the Northern Hemisphere, four are reported from
Papua New Guinea, and three are recorded from Macaronesia, continental
Africa, and Réunion. Plectocarpon is not known from Antarctica,
Greenland, the Pacific Ocean, Mexico, or Central America, nor from the
whole of Asia except for Russia and Turkey.
Seven taxa are currently accepted from Australasia, with P.
pseudosticta (the generitype) being known from Tasmania, New Zealand,
and Chile, P. gallowayii (an Australasian species transferred from
Melaspilea), and five newly described species namely P. bunodophori
(on Bunodophoron patagonicum and known from New South Wales,
Tasmania, and New Zealand), P. concentricum (on Pseudocyphellaria
homceophylla and apparently endemic to New Zealand), P. opegraphoideum
(on Pseudocyphellaria homoeophylla and P. multifida, and
apparently endemic to New Zealand); P. sticticola (on Sticta
caliginosa, S.filix, S. squamata, and S. subcaperata, and apparently
endemic to New Zealand, although some years ago the late Geoff Bratt
discovered galls on a Tasmanian collection of ''Dendriscocaulon'',
leading him to write to me that he had "found fertile
Dendriscocaulon!"), and P. tibellii (on Pseudocyphellaria rubella and
also apparently endemic to New Zealand).
Plectocarpon as discussed in the monograph comprises lichenicolous,
stromatic Roccellaceae (Arthoniales) with more or less carbonised,
multilocular stromata, many of which produce apothecia-like galls. The
generic delimitation, especially with respect to Opegrapha-like taxa,
is still unclear and needs resolution. Many species of Plectocarpon
are restricted to Peltigeralean hosts. Pseudocyphellaria is the host
genus richest in species of Plectocarpon, with at least 11 species
known, adding substantially to data on lichenicolous fungi (and
associated chemical patterns) from Pseudocyphellaria recorded earlier
by Kondratyuk & Galloway (1995). To set Plectocarpon in perspective, a
key is given to lichenicolous genera of Roccellaceae, including
Perigrapha (a new species is described from New Zealand), Opegrapha,
Plectocarpon, Sigridea, Enterographa, Mazosia, and Lecanographa.
Several species formerly included in Plectocarpon are transferred to
other genera, namely Arthonia sampianae, Enterographa epiphylla,
Sigridea labyrinthica, and three Plectocarpon-like taxa.
Enterographa punctata (from Sri Lanka), Opegrapha phaeophysciae
(from Russia), and Perigrapha nitida (from New Zealand) are newly de-
scribed. A key to all accepted species of Plectocarpon is given,
together with an account of the pigments, crystals, and pruina found
in the stromatic tissue, which are useful in species separation. Two
species of Celidium (C. bacidiosporum from Kenya and C. dubium from
New Zealand) are excluded from Plectocarpon.
Although the monograph is comprehensive in scope and detail, one gets
the impression that it is far from the final word, and in several
places the authors hint at areas deserving further study, with
fascinating vistas of speciation and co-evolution in both Plectocarpon
and the Lobariaceae to be explored in the future. I hope that this
excellent and timely compilation will be both a guide and a stimulant
to such studies in the near future. It is a fine addition to the
growing literature of lichenicolous fungi but more than that it offers
some solid pointers to new research agendas, which I hope will be
quickly taken up. From a Southern Hemisphere perspective, it is a
solid achievement and a particularly welcome development.
Congratulations to all concerned with its production.
References
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David J. Galloway
Australasian Lichenology 58, January 2006
