Nemania diffusa













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 m long x 6-7 m broad, the stipes averaging 80 m long, with apical apparatus amyloid, cuboid to inverted hat shaped, 2-3 m high x 1.5-2.5 m broad.

Ascospores 9.5-12.5 x 4-5.5 m, 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: Arige (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. Pyrnes 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 Mller, 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 Mller, 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.