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Nemania chestersii (J. D. Rogers & A. J. S. Whalley) Pouzar.
Stromata superficial, irregularly effused to elongate, rarely
erumpent and pulvinate, rarely uniperitheciate at margin, 0.4-50 mm long x
3-15 mm broad x 0.7-1 mm thick, carbonaceous; surface greyish black, brownish
black to dull black, with inconspicuous to conspicuous perithecial mounds, when
immature coated with a beige to grey hyphal layer; interperithecial tissue black,
basal tissue inconspicuous, black; margin abrupt.
Perithecia subglobose,
0.6-0.8 mm diam.
Ostioles minutely to coarsely papillate, conical, black.
Asci cylindrical, long-stipitate, the spore-bearing parts 75-85 µm
long, the stipes averaging 70 µm long, with apical apparatus amyloid, cuboid,
1.5-2.8 µm high x 2-2.5 µm broad.
Ascospores 13.5-17 x 5.5-7 µm, pale
to medium brown, ellipsoid-inequilateral
to oblong, frequently with narrowly rounded ends, 1-2-seriate in the ascus,
wall finely longitudinally striate, with a short inconspicuous germ slit 4-5 µm long
on the more convex side.
Specimens examined: FRANCE: Aričge (09): Montségur, 21 Apr. 2000,
JF-00040, on Ulmus sp.; Rimont, Grand Bois, 03 Jul. 1999, JF-99140, on
Fagus sylvatica; Rimont, Las Muros, 22 Jun. 2001, JF-01120, on Prunus
avium; Rimont, Saurine, 12 Feb. 2002, JF-02027, on Corylus avellana;
Haute Garonne (31): Lafitte-Toupičre, le Quillet, 02 Nov. 2002, JF-02212, on Corylus avellana.
Notes: Nemania chestersii seems widespread
in Europe, known from Czech Republic (Pouzar, 1985 b), Denmark (Granmo
et al., 1999), France, Great Britain, Switzerland (Petrini & Müller,
1986), but is rarely reported. Its highly variable stromata,
exhibiting a very wide
range of variations, from small, pulvinate and erumpent to widely
effused, with or without conspicuous perithecial mounds, with coarsely to minutely
papillate ostioles make it impossible to distinguish from
other taxa of Nemania resembling N. serpens. The distinctive feature of this species,
unique among European Nemania taxa, is the
ornamented wall of ascospores, visible in any mounting medium at 1000 x magnification.
The ascospore germ slit is said to be lacking by Rogers and Whalley (1978),
Petrini and Müller (1986) and Granmo et al. (1999). Indeed, it is inconspicuous
and partially hidden by the striate epispore, but mounting perithecial contents in
PVA Lactophenol allows to observe its situation on
the more convex side.
Nemania chestersii is not host-specific, and was recorded during this study
on wood or bark of Corylus avellana, Fagus sylvatica, Fraxinus excelsior,
Populus tremula, Prunus avium, Quercus robur, Quercus
rubra, Salix caprea and Ulmus sp.
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