Hypoxylon fragiforme (Pers.) J. Kickx., 1835
Common names: Beech woodwart [En], Hypoxylon en forme de fraise [Fr], Roestbruine kogelzwam [Nl], Rötliche Kohlenbeere [De]
Hamoir, LIEGE ● Belgium
Description: Stromata hemispherical to nearly spherical, frequently with conspicuous perithecial mounds, 2-9 mm diam x 1.5-7 mm high; surface rust (39) to bay (6), with orange-red granules beneath surface yielding KOH-extractable pigments orange (7), in early stages underlined by a conspicuous layer of white granules in which perithecia develop; the tissue below the perithecial layer black, massive, up to 6mm thick, extending upwards between the perithecia when aged.
Perithecia obovoid, 250-380 µm diam x 450-650 µm high.
Ostioles lower than or at the same level as the stromatal surface, black.
Asci 135-180 µm total length x 7-10 µm broad, the spore bearing-parts 64-92 µm long, the stipes 60-96 µm long, with apical ring amyloid, discoid, 1-1.3 µm high x 2.5-2.8 µm broad
Ascospores dark brown, ellipsoid-inequilateral, frequently crescent-shaped, 10-15 x 4.8-6.8 µm (M = 12.4 x 5.7 µm), with germ slit spore-length; perispore dehiscent in 10% KOH, smooth.
Anamorph in nature hazel (88), velvety, covering young stromata in early stages. Conidiogenous structure hyaline to slightly pigmented, roughened, Nodulisporium-like.Conidiogenous cells 15-27 x 3.3.5 µm. Conidia ellipsoid to nearly globose, 4-4.8 x 3.5-4 µm.
It can be easily confused with H. howeianum which has very similar stromata and which, although usually growing on various hosts, has been occasionally recorded on Fagus and sometimes mixed with it (Petrini & Müller, 1986; present study). A reliable identification of H. fragiforme, even on Fagus, therefore needs checking ascospores size. Hypoxylon howeianum differs mainly from H. fragiforme in having smaller ascospores (7-9 x 3.5-5 µm) and in being associated with a conspicuous anamorph growing on radiating hyphal chords at base of young stromata.
Habitat: Primary saprophyte on corticated branches or wood of Fagus sylvatica. Also occasionally recorded on Alnus, Betula, Carpinus, Populus, Quercus, Sorbus and Tilia (Enderle 1982, Petrini & Müller 1986, Kriegelsteiner 1989, present study).
Distribution: Europe and North America.
Pyrenomycetes from southwestern France