CRAPHIS ScnIPTA - Universitetet i Oslo

GRAPHTS SCRTPTA 5 (lee3) On Lichenoconium erodens and L. lecanorae 19
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Figure 1. Section of an apothecium of Lecanora conizaeoides with the hymenium destroyed by
Lichenoconium lecanorae. The surface of the hymenium is blackened by a dense layer of conidia
as well as by the pycnidia of the parasite. The hymenium is pale brownish with only faint traces of
its original structure. The algae below the hypothecium are likewise brownish and of unhealthy
appearance, while algae in the amphithecium are undamaged. The pycnidium in the centre of the
hymenium is photographed at a higher magnification in Figure 3.
Below to the right a small pycnidilm of Lichenoconiam erodens is seen, situated on a thallus-granule,
which is overgrown by the apothecium. This pycnidium is depicted at a higher magnification
in Figure 4. (Bar = 100 pm, neg. no. 92.762, slide no.92630, unstained).
such a modest part, when participating in a
mixed infection with L. lecanorae.
A possible explanation might be, that l.
lecanorae had been the first to establish itself
as a parasite on the lichen. At any rate the
pycnidia of L. lecanorae were often old, with
decayed conidiogenous cells, while the conidiogenous
cells could still be seen in the less
prominent pycnidia of L. erodens. Moreover,
some of the pycnidia of L. lecanorae, which
still contained a layer of conidia along the wall,
showed signs of deterioration and were inhabited
by colonies of bacteria and protococcoid
algae (Figure 3).
In sections the pycnidia of L. erodens were
identified by their generally (but not always)
smaller size and by their rather small conidia
(Figure 3).
The sections depicted in Figs. L-4 are
from two small bits of the same thallus of Lecanora
conizaeoides, taken within a distance of
less than 2 mm from each other. The sections
are made on a l-eitz Kryomat freezing microtome
at a thickness of 15 pm. The
preparations are mounted in lactophenol with
or without addition of stains, and photographed
with a Reichert Tntopan microscope
provided with photoautomatic equipment.
Acknowledgements
I am very greatful to my old friend, Gunnar
Degelius, for entrusting me with this interesting
material. Unfortunately, I have not yet
been able to conclude my studies on the still
undescribed coelomycete with acervular conidiomata.
The present note froy, however,
serve as a small advance.