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Nemania diffusa (Sowerby) S. F. Gray.
Stromata superficial, effused on wood or bark, discoid to elongate, 5-55 mm long x
5-15 mm broad x 0.8-1 mm thick, carbonaceous; surface dark brown to
blackish brown, with inconspicuous perithecial mounds, when immature coated with a white
to greyish hyphal layer; interperithecial tissue dark grey, carbonaceous; margin abrupt to
rarely narrowly effused.
Perithecia obovoid, 0.4-0.6 mm diam x 0.6-0.9
mm high.
Ostioles minutely to coarsely papillate, black.
Asci cylindrical, long-stipitate, the spore-bearing parts 70-80 µm
long x 6-7 µm broad, the stipes averaging 80 µm long, with apical apparatus
amyloid, cuboid to inverted hat shaped, 2-3 µm high x 1.5-2.5 µm broad.
Ascospores
9.5-12.5 x 4-5.5 µm, dark brown, ellipsoid-inequilateral with sometimes one end
beaked, uniseriate in the ascus, with a conspicuous straight germ slit spore-length
to nearly so
on the less convex side.
Specimens examined: FRANCE: Ariège (09): Ganac, ruisseau
de Ganac, 05 Jul. 2000, JF-00108, on Castanea sativa; Montseron, Roquebrune,
24 Aug. 2001, JF-01169, on Quercus robur; Rimont, Las Muros, 10 Mar.
1995, JF-95003, on Acer campestre; Rimont, Grillou, 25 Apr. 1999, JF-99068,
on Quercus robur; Rimont, Las Muros, 28 Oct. 2002, JF-02206, on Quercus
robur. Pyrénées Atlantiques (64): Pau, Bois Bastard, 16 Apr.
1995, FC-362, on Castanea sativa.
Notes: Nemania diffusa is the name reinstated by Ju and Rogers
(1996) for a taxon previously known in recent literature as Hypoxylon
bipapillatum (Petrini and Rogers, 1986), Hypoxylon serpens var. II
(Petrini and Müller, 1986) or Nemania bipapillata (Pouzar, 1985b). They
stated that the type of H. bipapillatum Berk. & M. A. Curtis
differs in having annulate ostioles and in having a more tropical distribution.
Nemania diffusa is characterized by strongly carbonaceous stromata
which keep a brown tinge even when fully mature, stromatal surface with inconspicuous
perithecial mounds, and dark brown ascospores with a conspicuous germ slit.
It should be compared with N. carbonacea Pouzar which has similar
ascospores but differs in that the stromatal surface is black with more
prominent perithecial elevations.
Nemania diffusa is widespread and fairly common in southwestern
France but records from France are scarse in literature, while it has been reported
from most of European countries including Czech Republic, Denmark, Germany,
Italy, Slovakia, Sweden, Switzerland and U. K. ( Pouzar, 1985b;
Petrini and Müller, 1986; Granmo et al., 1999). It has also been reported
from North and South America (Petrini and Rogers, 1986), Papua-New Guinea (Van
der Gucht, 1995) and Taiwan (Ju and Rogers, 1999).
Nemania diffusa was recorded during this study mostly on wood or bark
of Quercus robur but also occasionally on Acer campestre, Castanea
sativa, Corylus avellana, Hedera helix, Fagus sylvatica, Fraxinus excelsior,
Prunus spinosa and Rosa canina. Its occurrence on bamboo
(Candoussau et al., 1996) as H. bipapillatum is likewise
noteworthy.
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