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Rosellinia subsimilis Karsten & Starb.
Stromata uniperitheciate, scattered or in small groups
on uniformly blackened host surface, rarely fused together, dark brown to black,
rather soft-walled, subglobose with a conical apex, 0.7-0.9 mm diam; subiculum present
in first states of development as a brown tomentum on ascomal wall, evanescent, nearly absent
on mature stromata.
Ostioles minutely papillate, conical, black.
Asci cylindrical to ventricose in upper part, the spore-bearing part 110-140 µm long
x 15-18 µm broad, the stipes 60-70 µm long, with apical apparatus cylindrical to slightly urn-shaped,
amyloid, 7-9 µm high x 4.2-5.4 µm broad.
Ascospores 22-30 x 6.6-9 µm, frequently biseriate in the ascus, ellipsoid-inequilateral
with broadly rounded ends, nearly cylindrical in front view, light brown to brown, with a straight
to slightly oblique germ slit spore-length on the less convex side; both ends with a
triangular cellular appendage 2-2.5 µm long surrounded by a slimy cap; the slimy caps are best
seen in fresh material.
Anamorph on natural substrate: not observed.
Specimens examined: FRANCE: Ariège (09): Aulus les Bains,
cascades du Fouillet, 1000m, 10 Sept. 2004, JF-04201, on blackened decorticated small branches of
Fagus sylvatica; same location and same date, JF-04202, on blackened decorticated small branches
of Fraxinus excelsior.
Rosellinia subsimilis is characterized by subglobose stromata with
a conical apex associted with a non-persistent brown subiculum; its ascospores
are 19.5-29.5 x 5.5-8.5 µm, pale brown, more or less cylindrical with typically parallel
side walls, with a straight germ slit spore-length, and with a short triangular
cellular appendage at each end, surrounded by a fugacious slimy cap (Petrini,
1993).
Rosellinia subsimilis is reported by Petrini (1993) as very common
on herbaceous stems and branches in alpine regions of Europe (Switzerland, Scandinavia)
and North America (Canada). It shares the same habitat as R. abscondita
and R. nectrioides (Petrini, 1993). Rosellinia helvetica , found on small branches
of Fagus sylvatica mixed with those bearing R. subsimilis is externally
much alike but its stromata remain embedded in a persistent dark brown subiculum. These two collections
of R. subsimilis from Central Pyrénées are likely to be the first published
from France.
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