Hypoxylon fuscum (Pers.: Fr.) Fr.

TELEOMORPH | CULTURES AND ANAMORPH | SPECIMENS EXAMINED | NOTES

NOTES

Cultures and anamorph have been described by Greenhalgh and Chesters (1968) on MA, Jong and Rogers (1972) on PDYA, and Petrini and Müller (1986) on MA.

Hypoxylon fuscum, H. anthochroum, and H. subrutilum are very similar in their teleomorphic morphology. The main differences are in their anamorphs; the conidiogenous structure of H. fuscum is Virgariella-like, whereas those of H. anthochroum and H. subrutilum are Nodulisporium-like. Perithecial sizes sometimes can facilitate differentiation among H. anthochroum, H. subrutilum, and H. fuscum. Hypoxylon anthochroum and H. subrutilum have larger perithecia than H. fuscum. However, collections of H. fuscum from the Pacific Northwest of U.S.A. and occasionally other northern temperate zones have perithecial size similar to those of H. anthochroum. Also compare with H. chathamense, H. macrocarpum, and H. trugodes.

A broad ascospore size range of H. fuscum has been reported by Petrini and Müller (1986) and Petrini et al. (1987). They also emphasized that the ascospore germ slit has a "knick" or slight indentation.

Three specimens at NY were labeled as H. commutatum var. holwayanum by J. B. Ellis: Holway 144, 347, and 3679. The last specimen collected from oak was designated as the type by Saccardo and Ellis (in Saccardo, 1882b), and noted by J. B. Ellis on the envelope-"the original specimen determined by Saccardo". The other two, Holway 347 collected from plum and Holway 144 from an unknown substrate, are different from specimen Holway 3679 in having smaller ascospores (8.5-) 9-12 (-12.5) x 4.2-5.5 mm and in having orange granules. They may represent a variant of H. crocopeplum Berk. & M. A. Curtis or even a new taxon.

Hypoxylon fuscum is highly associated with Alnus, Corylus, and the Betulaceae in general. However, in the tropics, Hypoxylon fuscum seems to become less host-specific. Additional studies might further subdivide this species.

A specimen at WSP [U.S.A.: Washington, Klickitat Co., Bingen Mt., 18.10.1902, Suksdorf, W.N., decorticated wood, as H. pruinatum by ?, as H. novemexicanum by Miller, J.H. (WSP 27510)] is morphologically similar to H. fuscum except for having mouse gray (118) or purplish gray (128) stromatal surface and having ostioles slightly higher than the stromatal surface.