Euepixylon udum

              

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JF02215

JF02215

JF02140

JF02140

JF97010

JF97010

JF02140

JF97010

Euepixylon udum (Pers.: Fr.) Laess°e & Spooner.

For synonyms, see Laess°e & Spooner, 1994.

Stromata immersed to half-erumpent, usually multiperitheciate, linear 1.5-10 mm long, often coalescent and forming broader patches; stromatal surface dark brown to black, when young with an ochreous-white powdery coating, forming a clypeoid carbonaceous layer 60-120 Ám thick extending deeply into the substrate. Perithecia subglobose to obovoid, 0.5-0.9 (-1.1) mm diam x 0.7-1.1 mm high. Ostioles papillate, broadly conical, black. Asci short-stipitate, with discoid amyloid apical ring 1.5-2 Ám high x 4-5 Ám broad. Ascospores brown, ellipsoid nearly equilateral, 23-32 x 9-12.5 Ám, with a poroid ellipsoid germ slit 5-7 Ám long x 2-3 Ám broad, on the more convex side when ascospores are inequilateral; immature ascospores with a fugacious and inconspicuous hyaline rounded cellular appendage 2 x 2 Ám.

Specimens examined: FRANCE: AriŔge (09): Rimont, Las Muros, 14 Nov. 1996, JF-96165, on Acer campestre; Rimont, Las Muros, 12 Jan. 1997, JF-97010, on rotten wood of Quercus robur; Rimont, Las Muros, ruisseau de Peyrau, 25 Sept. 2001, JF-01204, on rotten wood of Corylus avellana; Rimont, Las Muros, ruisseau de Peyrau,15 Aug. 2002, JF-02140, on rotten wood of Quercus robur; Rimont, Grillou, 13 Nov. 2002, JF-02215, on rotten wood of Quercus robur.

Notes: Euepixylon udum is not uncommon but rarely reported, owing to its inconspicuous stromata that are easily overlooked. Moreover, it is easily confused with Nemania confluens (Tode: Fr.) Laess°e & Spooner which is macroscopically similar in having a few perithecia more or less immersed under a black clypeoid stromatal crust extending into the substrate. Nemania confluens differs from E. udum in having shorter ascospores with more narrowly rounded ends and a straight germ slit spore-length.

Euepixylon udum is so far known from Europe (Petrini and MŘller, 1986; Granmo et al., 1999, Laess°e et al., 2000), and constantly grows on decorticated rotten sapwood, mostly of Quercus, but also found on Corylus and once on Acer campestre.