Book of Abstracts (PDF) - International Mycological Association

IMC7 Thursday August 15th Lectures
281 - Amber fossils of sooty moulds
J. Rikkinen
Department of Applied Biology, P.O. Box 27, FIN-0014,
University of Helsinki, Finland. - E-mail:
jrikkine@mappi.helsinki.fi
Fungi are unlikely candidates for fossilization and thus
relatively few fungal fossils have been described. However,
perfectly preserved amber fossils have shown that many
modern genera of fungi, and possibly even species, were
already present in the Tertiary. For example, several well
preserved specimens of sooty moulds were recently found
from European amber dating back to 22-54 million years
ago. The fossils represent fragments of superficial subicula
composed of brown moniliform hyphae with markedly
tapering distal ends. The subglobose cells are quite
identical to those of extant Metacapnodium
(Metacapnodiaceae, Dothideales) species. Also the
production of two distinctive conidial states supports a
placement in this extant genus. The fossils demonstrate that
the hyphae of some sooty moulds have remained
unchanged for tens of millions of years. As there is little
reason to believe that the fossilizations would have been
immediately preceded by a period of more rapid evolution,
the initial divergence of the fungi must have happened in
the distant past, probably in the Cretaceous. The fossils
also indicate that hyphal morphology and conidial states
can be given considerable classificatory significance in this
group of fungi. Eventually, after more detailed
phylogenetic hypotheses have been generated for different
groups of sooty moulds, the available fossils can become
invaluable for timing branching events and calibrating
molecular clocks.
282 - Molecular systematics of some sooty molds
J.L. Nicklin
Biological Sciences, Birkbeck, University of London, Malet
Street, London, WC1E 7HX, U.K. - E-mail:
j.nicklin@bbk.ac.uk
Sooty moulds are a community of several hundred darkly
pigmented mitosporic and ascosporic species of fungi,
living on tropical plant surfaces in association with
honeydew from insect infestations. All phases of the life
cycle of these fungi retain a melanised cell wall creating a
sooty layer on leaf surfaces. Mitospores of many of the
species are formed on a variety of pycnidial or coremial
structures, all of which appear to be adaptations to the leaf
surface environment that maximise spore dispersal after
wetting. This guild of fungi was extensively studied on
citrus and other tropical plant species during the late 19th
C, and at that time was given the common epithet
Capnodium citri (Farlow, Underwood). It is now realised
that this an ambiguous name for a polymorphic group. The
systematics of these fungi and their interactions with plants
and aphids is of interest as the economic effects of sooty
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Book of Abstracts
mould colonisation of citrus, pecan and other
horticulturally important plants begins to become apparent.
The taxonomic status of some of the sooty moulds has
recently received some clarification based on
morphological and physiological characters. However, the
complexity of the associations mean that identification
based on morphological and biochemical features is
unsatisfactory and molecular approaches reported in this
work, including RAPD, microsatellite fingerprinting and
ITS sequence analysis, provides better data for taxonomic
and cladistic analysis.
283 - Foliicolous ascomycetes in the canopy of a lowland
rainforest in the Orinoco Basin, Venezuela (Surumoni
Crane Project)
P. Otto 1* & D.R. Reynolds 2
1 University of Leipzig, Institute of Botany, Systematic
Botany, Johannisallee 21-23, D-04103 Leipzig, Germany. -
2 Natural History Museum, Research and Collections, 900
Exposition Boulevard, Los Angeles, California 90007,
U.S.A. - E-mail: otto@rz.uni-leipzig.de
The fungi were investigated from the forest floor to the
upper canopy (till 35 m height) in an area of 1.5 ha of an
evergreen forest using a mobile crane system. Data are
available from 1996 to 1998 for rain and dry season and for
leaves of different ages. The studied fungi, teleomorphs
and selected characteristic anamorphs, belong to saprobic,
plant pathogenic or fungal pathogenic species and were
collected from trees of 25 plant families. Fungi of 15
genera in 12 families were identified in the canopy. Typical
genera for tree crowns are e.g. Atichia, Brefeldiella,
Brooksia, Microthyrium, and Myriangiella. The most
common genus is Micropeltis, which occur on all tree
species with a sufficiently thick leaf cuticle and produce
first fruitbodies on leaves of an age of about 2 months. The
fungal diversity (including saprobic fungi) is very different
for individual tree species. Trees particularly in the
Annonaceae and Caesalpiniaceae have a high fungal
species number. Diversity and quantity decrease from the
lower and medium canopy to the top. Probably
unfavourable climatic conditions (till about 35 °C and 40%
rel. humidity) are responsible for it. This assumption is
supported by the fact that in the crane site at the end of rain
season foliicolous ascomycetes are best developed. Some
of these have a preference for the undersurface of leaves,
e.g. Schizothyrium, which is a further indication of the
strong influence of temperature and humidity on leaf
inhabiting fungi.