CRAPHIS ScnIPTA - Universitetet i Oslo

70 Manin Grube and Josef Poelt
Figure 1. Sagema potentillae. a) ascus (bar = 20 pm) with a detail of the tholus stained in iodine.
b) spores (bar = 20 pm); one spore with a detail of the wall; another spore with reticulate plasma.
c) secfion through an ascocarp @ar = 200 pm).
30 July 1986, G. & S. Miehe 7307a (GZIJ,
holotype; M, UPS, isotypes). (Soc. c. Cetraia
sp. Nephroma sp.)
In the holotype material the lichen grows on
rather thin, dead twigs of. Potentilla arbuscula
S. Don (group of P. fruticosa L.).The thallus
is thin, crustose, well developed only at the
circumference of the apothecia, whitish to
sordid greyish-white, ecorticate, and it contains
coccal greenalgae. The algal cells are
roundish and rarely exceeding 1,I pm in diameter.
Apothecia often arranged to groups, about
0.3-0.6 pm in diameter, sessile, with constricted
base. Disc dark red-brown, epruinose,
even, but occasionally with minute humps
caused by protruding ascus tips; when moistened
the asci are recognized as clear points
under the stereo microscope. Thalline margin
distinct, not or only when young slightly protruding,
then dwinilling, whitish to ochraceous
white, not or slightly crenate. The amphithe-
GRAPHTS SCRTPTA 5 (1993)
l0H
cium consists of an dense algal layer extending
up into the rim of the margin, where a ringformed
pseudocyphella is formed betrveen the
cortex and the parathecium. Below the algal
layer, in the centre of the apothecia, a hydrophobous
medulla extends down to the substrate.
The amphithecium is bordered by a
cortex 60- 100 pm built up by anticlinal,
strongly gelatinized hyphae with filiform
lumina. The cortex is studded by polarizing
grains (soluble in K, insoluble in N).
Hypothecium up to I0 pm thick, of slightly
horizontal hyphae, c. L pm wide, embedded in
a diffuse matrix. Subhymenium c. L5 pm in
height. Hymenium c. L20-140 pm high; the
pale brown epihymenium occupying c. 20 pm
of the hymenium height. Paraphyses with +
distinct anastomoses, the lumina c. 0.5-0.7 pm
thick, the outer wall layer gelatinized; polarrzing
grains (soluble in K, insoluble in N) are
present between the tips of the paraphyses,
too. Asci functionally unitunicate, with rostrate
mechanism, clavate to saccate, c. 80- 100 x