:Xylariaceae: Hypoxylon

GENERIC DESCRIPTION

Stromata glomerate, pulvinate, discoid, effused-pulvinate, hemispherical, spherical, or peltate, solitary, or confluent, with broad or narrow attachment to the substrate; surface colored or black, pruinose or polished, plane, or with inconspicuous or conspicuous perithecial mounds; waxy or carbonaceous tissue immediately beneath surface and between perithecia, with or without KOH-extractable pigments; the tissue below the perithecial layer inconspicuous, conspicuous, or massive, dark brown to black, sometimes whitish, woody or coriaceous, persistent.

Perithecia spherical, obovoid, tubular, or long tubular, monostichous, with or without carbonaceous stromatal material surrounding individual perithecia.

Ostioles lower than the level of stromatal surface (umbilicate), at the same level of stromatal surface, or higher than the level (papillate) of stromatal surface, with or without discs formed by dehiscence of surrounding tissue.

Asci eight-spored, cylindrical, stipitate, persistent, with apical ring discoid, amyloid or infrequently inamyloid, distinct, highly reduced or apparently lacking.

Ascospores pale brown, light brown, brown, dark brown, or blackish brown, unicellular in both mature and immature ascospores, ellipsoid or short fusoid, inequilateral, slightly inequilateral or nearly equilateral, with acute, narrowly rounded, or broadly rounded ends, with straight, sigmoid, or spiral germ slit spore-length to much less than spore-length on the convex side or, less frequently, on the flattened side; perispore dehiscent or indehiscent in 10% KOH, smooth or with inconspicuous to very conspicuous coil-like ornamentation, or with a thickened area at the position of ca. 1/3 ascospore length; epispore smooth or sculptured.

Conidiophores mononematous or infrequently synnematous, usually macronematous, hyaline or colored, smooth or roughened, with a dominant main axis that is unbranched or bears one or more major branches, or without a dominant main axis, with or without additional branches which originate from the conidiogenous regions and are generally similar to the original conidiophore.

Conidiogenous cells cylindrical, hyaline or lightly colored, smooth or roughened, one to several on each terminus of conidiophore, with conidiogenous regions at apex that are swollen to various degrees due to successive conidial production. The morphology of the conidiogenous region is influenced by age; old regions are often more inflated and colored. Conidiogenous regions with poroid or, infrequently, denticulate conidial secession scars.

Conidia produced sympodially in more or less basipetal succession (see Cole, 1971), subglobose to ellipsoid, hyaline or lightly colored, smooth or finely roughened, with flattened base indicating former point of attachment to conidiogenous cells, typically dry and, apparently, wind-dispersed.