Rosellinia mycophila

              

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JF97128

JF97128

JF97128

JF97128

JF97128

JF97128

JF97128

Rosellinia mycophila (FR;: Fr;) Sacc.

Stromata usually densely gregarious, uniperitheciate, rarely fused together in a 2-3- peritheciate stroma, dark brown to black with a thin coating of pale subicular hyphae, subglobose with a broadly attached base, 0.6-0.7 mm high x 0.8-1 mm diam, with conspicuous folds and ridges in the lower part when dry; ectostroma rather thin, brittle; subiculum densely felted, purplish brown, of finely interwoven hyphae, persistent, widely spreading.

Ostioles stout, broadly conical, darker than the stromatal wall.

Asci cylindrical, with apical apparatus urn-shaped with attenuated base, amyloid, 5.5-6 Ám high x 4.5-4.8 Ám broad.

Ascospores 17-21 x 5.5-6.5 Ám, ellipsoid-inequilateral with one end slightly pinched, the opposite narrowly rounded with an inconspicuous cellular appendage 2 Ám long, dark brown, with a short, straight germ slit 8-13 Ám long on the less convex side; the whole spore surrounded by a conspicuous slimy sheath reducing with age.

Anamorph in nature: not seen.

Specimens examined: FRANCE: AriŔge (09): Rimont, Las Muros, 08 Aug. 1997, JF-97128/2, on twigs and needles of Picea abies, mixed with R. thelena.

Notes: It was quite by chance that R. mycophila was found on a twig of Picea abies mixed with other twigs bearing R. thelena. These two species are fully similar in external appearance, and can only be separated by microscopical features of ascospores. Ascospores in R. mycophila are a bit shorter than in R. thelena, with a shorter germ slit, an inconspicuous blunt cellular appendage and a slimy sheath around the whole spore. Above all, they lack the distinctive pointed appendages typical of R. thelena and its var. microspora.

Rosellinia mycophila was reported by Francis (1986) as a severe pathogen of conifers [under R. minor (von H÷hnel) Francis] in Europe and North America, and its differences with R. herpotrichoides Hepting & Davidson discussed. This pathogen activity seems to be an additional difference with R. thelena, which has only been reported as a primary saprophyte.