The stromatal surface may be
plane
to slightly convex and then with
low margins
to more or less
concave
or cupulate, and then with thick
raised margins,
B. marginata...).The
stromata are considered carbonaceous when, sectionned with a razor
blade, they turn out to be broken rather than properly cut.
The dehiscing outer layer is only seen on very young stromata, and
therefore is rarely observed. It can be
thin and torn up,
operculum-like
to
crust-like.
Ostioles may be
umbilicate
or
discoid
when opening lower than stromatal surface, to
papillate
or
coarsely papillate
when opening higher than stromatal surface.
Perithecia may be
obovoid
to
tubular,
, but in some species this character may be variable within a same collection.
Ascospores may be one-celled to
two-celled,
ellipsoid
to
subglobose,
with a germ slit that can be
straight,
sigmoid
or
bilateral.
.
The germ slit morphology is frequently a
diagnostic character
and its observation is made easier by the use of mounting media such as
lactic acid or lactophenol which improve the clearness. Permanent mounts
of ascospores in Polyvinylic alcohol (Rhodoviol®)* dissolved in lactophenol
(Van Brummelen, 1967)
make the germ slits particularly conspicuous. Bilateral germ slits are best
observed on ascospores that are not exactly in front view, when focusing alternately
on upper and lower side.
* Rhodoviol 50g, water 150g, lactic acid 80g, phenol 40g.
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