Nemania confluens (Tode: Fr.) Laessøe & Spooner.
Stromata fully immersed to nearly superficial, typically uniperitheciate
but often coalescent in linear rows or in small groups with up to 5 (-10)
perithecia beneath a carbonaceous outer stromatal layer 130-150 µm thick
extending into the substrate, subglobose, dark brown to dull black, 0.6-1 (-1.7)
mm diam, frequently with a flattened apex, when young emerging from a copious
white hyphal tissue; interperithecial tissue greyish, soft, inconspicuous.
Perithecia subglobose, 0.5-0.8 (-1.2) mm diam.
Asci cylindrical, short-stipitate, the spore-bearing parts 105-125
µm long x 10-12 µm broad, the stipes 25-40 µm long, with apical apparatus amyloid, cuboid
to inverted hat-shaped, 2.5-3 high x 3-4.5 µm µm broad.
x 8-9.5 µm, dark brown, ellipsoid nearly equilateral with narrowly rounded ends,
uniseriate in the ascus, with a conspicuous straight to slightly sinuous germ
on the less convex side when ascospore is inequilateral.
Specimens examined: FRANCE: Ariège (09): Rimont, Las
Muros, 15 Jun. 1995, JF-95005, on Quercus robur; Rimont, Las Muros, ruisseau
de Peyrau, 09 Aug. 1998, JF-98099, on Quercus robur; Rimont, Las Muros,
06 May 2001, JF-01086, on Corylus avellana; Prat Communal, ruisseau de
Loumet, 1000 m elev., 02 Jul. 2001, JF-01135, on Abies alba. Dordogne
(24): Lalinde, Courcelles, 25 Dec. 1999, JF-99294, on Robinia pseudoacacia.
Haute Garonne (31): Couladère, ruisseau de Tounis, 18 Jan. 2003,
JF-03012, on Quercus robur.
Notes: Nemania confluens is distinctive among other Nemania taxa in
having uniperitheciate stromata usually partially immersed in the substrate,
short-stipitate asci with a cuboid apical apparatus and nearly equilateral ascospores. Granmo
et al. (1999) assume
it should be removed from Nemania.
In the field, it may be easily confused with the small stromata of Euepixylon
udum (Pers.: Fr.) Laessøe & Spooner, an other xylariaceous
fungus which also grows more or less immersed in very rotten wood of Corylus
and Quercus. Ascospores of E. udum differ from those of
N. confluens in being much longer, averaging 25-27 µm long, paler,
with broadly rounded ends and a poroid germ slit.
Nemania confluens is so far known from Europe [Miller, 1961 (as Hypoxylon
confluens); Dennis, 1978 (as Hypoxylon semiimmersum); Petrini
and Müller, 1986 (as Hypoxylon confluens); Granmo et al., 1999],
but also reported by Ju and Rogers (2002) from Chile and U. S. A. It is not uncommon, and
always found on very rotten decorticated sapwood, most often of Corylus
and Quercus, but appears to be plurivorous, as pointed out by Miller
(1961) and Granmo et al. (1999). A collection on a small dead standing
rotten trunk of Abies alba (JF-01135) is noteworthy as Nemania taxa
very rarely recorded on Gymnospermous wood (Granmo et al., 1999).