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Family: XylariaceaeGenus: Amphirosellinia
Stromata 1.5-2(-2.5) mm diam., usually containing a single ascoma but rarely including 2-3 fruit-bodies, erumpent through bark, strongly aggregated, splitting the host periderm in a stellate pattern (often 4-lobed), ± hemispherical, the ostiolar region conical and the ostiole papillate, dark brown to black with amorphous remains of ectostromal matter sometimes persisting on the outer surface. Entostroma carbonized, dark brown to black, brittle, basal entostroma rudimentary.
Anamorph formed on the surface of young stromata, Dematophora-like, synnematous. Conidiogenous cells in a palisade, proliferating sympodially, geniculate, with persistent scars. Conidia 6.5-8.5 x 3-4 (-4.5) µm, lacrymiform, the base truncate, hyaline, aseptate, smooth-walled.
Teleomorph: ascomata perithecia, 0.8-1 mm diam., ± spherical. Interascal tissue of copious fairly thin-walled unbranched paraphyses ca 3 µm diam. Asci 165-175 x 12-13 µm, cylindrical with a long tapered stipe 50-100 µm long, the apex rounded with a very conspicuous barrel-shaped to truncate-conical apical apparatus 6-8 µm diam. and 7-10 µm deep, staining dark blue in Lugol's iodine, 8-spored. Ascospores 22-25 (-26.5) x 9-10.5 µm, slightly inaequilateral to elongate-fabiform, the ends rounded, dark chocolate brown, aseptate, smooth, with a helical germ slit extending the entire length of the spore, with a thin evanescent gelatinous sheath.