You are here
Family: ValsaceaeGenus: Leucostoma
Anamorph: conidiomatal locules formed within the stromata, often multilocular, convoluted and radiating from the centre, probably preceeding perithecial formation. Conidiophores 6-25 µm long, hyaline, septate, branched irregularly at the base and above, formed from the inner cells of the locule walls. Conidiogenous cells not clearly distinct morphologically from the conidiophores, usually formed as long distinct branches, straight, hyaline, smooth, proliferating percurrently, collarette and periclinal thickening inconspicuous. Conidia 4.5-8 x 0.5-2 µm, cylindrical to allantoid, hyaline, thin-walled, aseptate, without guttules, often extruded in sticky orange-red tendrils.
Teleomorph: stromata 1-2 mm diam., truncate-conical, prominent, containing 6-12 ascomata. Ectostromatic disc 300-350 µm diam., almost pure white, with the black tips of the perithecial necks just emerging. Entostroma greyish to brownish, composed of interwoven hyphae with some host cells intermixed in the lower part, well-developed, delimited by a conspicuous black stromatic zone line, particularly prominent beneath the perithecia. Ascomata perithecia, 200-625 µm diam., ± globose with elongate necks 200-550 µm long and 100-300 µm diam. at the base, black, upright to oblique, necks converging, emergent through the disc but only just exceeding the upper surface. Peridium 10-12 µm thick, composed of dark, thick-walled angular cells. Interascal tissue absent, but neck periphysate. Asci often predominantly 4-spored and then measuring 35-40 x 8-9 µm, alternatively 8-spored and measuring 41-48 x 8-9 µm, cylindrical-clavate with a tapering base, apically thickened, with a refractive I- apical ring, becoming detached within the perithecial cavity. Ascospores 12.5-17 x 2.5-3 µm in 4-spored asci, 10-15 x 2.5-3 µm in 8-spored asci, allantoid to cylindrical, hyaline, aseptate, smooth- and thin-walled, without a gelatinous sheath or appendages.