Biscogniauxia repanda










Biscogniauxia repanda (Fr.: Fr.) Kuntze.

Stromata cupulate, discoid to ellipsoid, 10-25 mm long x 6-10 mm broad x 3 mm thick, with raised and crenate black margin; surface shiny black to dull black, carbonaceous; tissue beneath perithecia 2 mm thick, greyish to brown, with melanized tissue.

Perithecia obovoid to tubular, 0.5-0.75 mm diam x 0.9-1.2 mm high.

Ostioles discoid, papillate, infrequently at the same level as the stromatal surface.

Asci short-stipitate, with discoid and amyloid apical ring.

Ascospores brown, ellipsoid with narrowly rounded ends, 10-12 x 4.5-5 µm, with straight germ slit on both sides.

Specimens examined: FRANCE, Ariège (09): Orlu, Réserve Nationale d'Orlu, Jasse de Justiniac, 1280 m. elev., 28 Sept. 2001, JF-01213, on Sorbus aucuparia; Saurat, Forêt de Sauzet, Bois de Lagrié, 1100 m. elev., 16 Aug. 1999, JF-99186, on Sorbus aucuparia.

Notes: Biscogniauxia repanda is characterized by cupulate black stromata with raised margin, combined with papillate ostioles and ellipsoid ascospores with germ slit on both sides. It may be confused in the field with B. simplicior and B. marginata. The former differs in having umbilicate ostioles, larger ascospores with germ slit on one side and in being restricted to Rhamnus catharticus, the latter in having more rounded stromata with always umbilicate ostioles and blackish subglobose ascospores with a sigmoid germ slit.

Moreover, B. repanda has a hemiboreal to boreal distribution (Granmo et al., 1989) in Europe and North America and occurs mostly on Sorbus sp. This is apparently the first published record of this species from France, in central Pyrénées.