Rosellinia subsimilis

              

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JF04201

Rosellinia subsimilis Karsten & Starb.

Stromata uniperitheciate, scattered or in small groups on uniformly blackened host surface, rarely fused together, dark brown to black, rather soft-walled, subglobose with a conical apex, 0.7-0.9 mm diam; subiculum present in first states of development as a brown tomentum on ascomal wall, evanescent, nearly absent on mature stromata.

Ostioles minutely papillate, conical, black.

Asci cylindrical to ventricose in upper part, the spore-bearing part 110-140 m long x 15-18 m broad, the stipes 60-70 m long, with apical apparatus cylindrical to slightly urn-shaped, amyloid, 7-9 m high x 4.2-5.4 m broad.

Ascospores 22-30 x 6.6-9 m, frequently biseriate in the ascus, ellipsoid-inequilateral with broadly rounded ends, nearly cylindrical in front view, light brown to brown, with a straight to slightly oblique germ slit spore-length on the less convex side; both ends with a triangular cellular appendage 2-2.5 m long surrounded by a slimy cap; the slimy caps are best seen in fresh material.

Anamorph on natural substrate: not observed.

Specimens examined: FRANCE: Arige (09): Aulus les Bains, cascades du Fouillet, 1000m, 10 Sept. 2004, JF-04201, on blackened decorticated small branches of Fagus sylvatica; same location and same date, JF-04202, on blackened decorticated small branches of Fraxinus excelsior.

Rosellinia subsimilis is characterized by subglobose stromata with a conical apex associted with a non-persistent brown subiculum; its ascospores are 19.5-29.5 x 5.5-8.5 m, pale brown, more or less cylindrical with typically parallel side walls, with a straight germ slit spore-length, and with a short triangular cellular appendage at each end, surrounded by a fugacious slimy cap (Petrini, 1993).

Rosellinia subsimilis is reported by Petrini (1993) as very common on herbaceous stems and branches in alpine regions of Europe (Switzerland, Scandinavia) and North America (Canada). It shares the same habitat as R. abscondita and R. nectrioides (Petrini, 1993). Rosellinia helvetica , found on small branches of Fagus sylvatica mixed with those bearing R. subsimilis is externally much alike but its stromata remain embedded in a persistent dark brown subiculum. These two collections of R. subsimilis from Central Pyrnes are likely to be the first published from France.