Biscogniauxia mediterranea (De Not.) Kuntze.
Stromata applanate to slightly convex, broadly ellipsoid to elongate,
13-80 mm long x 5-18 mm broad x 1-1.2 mm thick; surface dull black to shiny black, carbonaceous,
with a dark brown to blackish outer layer long persisting at margin; margin effused to infrequently
conspicuously raised, black and carbonaceous; tissue beneath perithecia
0.2-0.5 mm thick, of whitened host tisue; a dark brown pulverulent layer 1-2
mm thick present between the base of the stromata and the surface of underlying
Perithecia obovoid to tubular, 0.2-0.3 mm diam x 0.6-0.8 mm high.
Ostioles coarsely papillate, black.
with apical ring discoid, amyloid.
Ascospores dark brown, ellipsoid with
narrowly rounded ends, 14-19 x 7-9 µm, with straight germ slit spore-length.
Specimens examined: FRANCE, Ariège (09): La Bastide de Sérou, Rhodes,
chemin d'Antuzan, 19 Oct. 2001, JF-01225, on Carpinus betula; Rimont,
Saurine, 13 Jun. 1996, JF-96075, on Corylus avellana; Rimont, Grand bois,
22 Mar. 1999, JF-99046, on Fagus sylvatica. Pyrénées Atlantiques (64):
Oloron Ste. Marie, Forêt de Bugangue, 23 Apr. 1995, FC-5326, on Fagus sylvatica.
Notes: Biscogniauxia mediterranea is characterized by
applanate black stromata with coarsely papillate ostioles and large ellipsoid
ascospores with a straight germ slit on one side. Other taxa featuring applanate
stromata and papillate ostioles are B. cinereolilacina and B. nummularia.
The former differs in surface colour which is purplish to grey and in ascospore
germ slit which is circular, the latter in less strongly papillate ostioles
and smaller ascospores.
In several collections of B. mediterranea ( JF-96075, JF-01225, FC-5326
), the stromatal margin is conspicuously raised
and thick, recalling what is the distinctive feature of the section Scleraster
erected by Pouzar (1986). This stromatal character of B. mediterranea is
rare but not exceptional, therefore we kept it in both parts of our dichotomous
key which follows Pouzar's sections.
Biscogniauxia mediterranea is reported from Africa, Central America,
Europe, U. S. A. and Russia (San Martin Gonzáles and Rogers, 1993; Ju et
al., 1998) and is not host-specific.