TYPE. UNITED STATES. Arkansas, Franklin County, Ozark National Forest, Cherry Bend Campground along Ark Highway 23, in deep valley on mixed hardwood forest, on Flavoparmelia caperata, 1.VI.1966, C.M. Wetmore 14058 (MIN 872083, holotype).
Life form. Lichenicolous fungus.
Description. [Modified from Hawksworth et al. (2004)] Thallus absent; photobiont absent. Ascomata perithecoid within stromata. Stromata arising on the surface of the host thallus, black, matt to slightly shiny, orbicular to somewhat irregular in surface view, shallowly convex, (0.35-)0.5-1.25(-2) mm diam., surface bullate, raised in mounds over the included perithecial locules, with to 5-10 locules immersed in each stroma. In section, stromata (150-)200-350(-400) um thick, dark brown to black throughout, composed of thick-walled pseudoparenchymatous cells, often occluded with dark contents, ±homogeneous in structure. Perithecioid locules arising deep in the stroma, ~130-170 μm diam. (excluding the excipulum and ostiolar canal), with an immersed elongated ostiolar canal 70-100 μm tall extending to the surface of the stroma. Exciple surrounding the perithecial locules similar in structure to the stromatal tissue, cells pseudoparenchymatous, somewhat angular, thick-walled, often unevenly so, dark brown, mainly 3-5 μm diam., somewhat radially compressed. Hamathecium well-developed, persistent, consisting of cellular pseudoparaphyses, regularly septate, branched, and 1.5-2.5 μm wide; centrum tissues I- (Lugol’s after KOH pre-treatment). Asci elongate-clavate, bitunicate in structure, apex thickened with an internal apical beak, I- (Lugol’s after KOH pre-treatment), 59-83 x 15-16 μm, (6-)8-spored. Ascospores monostichously to distichously arranged in the asci, 3-septate, a central pore sometimes conspicuous in the septa, generally strongly constricted at the septa, broadly fusiform, often slightly curved, rounded at the apices, olivaceous brown, the tips of the end cells often somewhat paler to subhyaline, smooth-walled, (22.5-)25-32(-38) x (7.5-)8-8.5(-9.5) μm. Conidiomata pycnidial, 70 μm diam., included in the stroma near the perithecial locules; dark brown to black, wall composed of 4-5 layers of pseudoparenchymatic cells, cells brown, irregularly polyhedral, 3-6.5 μm diam. Conidiophores absent; conidiogenous cells hyaline, short-ampulliform; conidia arising singly, hyaline, simple, mostly cylindrical, sometimes ellipsoid, rounded at the apices, 3 x 1.5 μm.
Hosts: [From Hawksworth et al. (2004)] "Flavoparmelia baltimorensis and F. caperata (thallus). The infected thalli appear blotched due to the numerous black stromata, but areas around the infections retain their normal yellow-green color; in section, algal cells in the immediate proximity of the stromata appear healthy in microscopic sections and there is no evidence of invasive hyphae penetrating the medullary tissues. The species therefore appears to be essentially commensalistic or weakly parasitic with respect to entire thalli."
Distribution. South central (Ozark highlands) and eastern (Alabama, southern Appalachian Mountains) North America; in North Carolina found in the Blue Ridge ecoregion.
Literature
Hawksworth, D.L., V. Atienza & M.S. Cole (2004) Lichenicolous species of Homostegia (Dothideomycetes), with the description of H. hertelii sp. nov., a new fungus on Flavoparmelia species. Bibliotheca Lichenologica88: 187-194 (original description).