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Family: XylariaceaeGenus: Astrocystis
Conidiomata absent. Conidiophores aggregated into loose pustules, sinuous, unbranched or dichotomously branched, hyaline to pale brown, smooth. Conidiogenous cells 5-20 x 3.5-4.5 µm, terminal, cylindrical, smooth, proliferating sympodially, with lateral and terminal discoid secession scars 1-1.5 µm diam. x 0.5-1 µm high. Conidia 4-5.5 x 2.5-3 µm, ellipsoidal, hyaline to pale olivaceous, smooth, with flattened bases 1-1 .5 µm diam. indicating former points of attachment to the conidiogenous cell [data from Ju & Rogers 1994].
Stromata containing 1-2 (-4) ascomata, 600-800 µm diam. and 400-600 (-700) µm tall, sometimes coalescing, erumpent through the cuticle, irregular in shape but usually ± mammiform with an inconspicuous non-papillate ostiole, surrounded when young by a ± flat stromatic skirt; black, ± smooth. Stromatal tissue carbonaceous, to ca 80 µm thick above the ascomata and rather less laterally, composed of small completely occluded cells apparently intermediate between epidermoid and hyphal in nature. Ascomata perithecia, 320-500 µm diam. and 240-280 µm tall, subglobose to oblate, thin-walled, composed of pale brown thin-walled ± straight hyphae to 4 µm diam., interspersed with small melanin deposits. Interascal tissue of copious rarely branched broad thin-walled paraphyses to 6 µm diam., tapering somewhat towards the ± obtuse apices. Asci 140-170 x 8.5-9.5 µm, cylindrical, the stipe quite short and gradually tapering, fairly thin-walled, not fissitunicate, the apex rounded, with a large truncate-obconical apical ring to 4 µm diam. and 7.5 µm thick that stains blue in iodine, 8-spored. Ascospores arranged ± uniseriately, 20-23 x 7.5-9.5 µm, fusiform-ellipsoidal and strongly inaequilateral with the flattened side flat to slightly concave, occasionally slightly beaked at one end, dark brown, smooth, with a ± straight germ slit entending the length of the spore on the concave side, sometimes with a short gelatinous appendage at one or both ends and more rarely with a prominent gelatinous sheath.