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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.
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