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Family: PhyllachoraceaeGenus: Stigmatula
Lesions usually not clearly differentiated.
Anamorph: not definitely recorded for Stigmatula astragali sensu stricto, but Rhodosticta-like conidiomata probably exist.
Teleomorph: stromata variable in size, often extending over whole leaflets, pale yellow, causing significant hypertrophy of the leaf tissue. Stromatic tissue composed of modified host cells with intra- and intercellular hyphal development, the internal portion filled with crystalline starch deposits, which blue in iodine at certain stages of development. Ascomata 10–50 per stroma, ostiolate on the undersurface of the leaf, strongly domed, visible from the surface as hemispherical matt or shining black structures 120–180 μm diam., sometimes coalescing, the ostiole inconspicuous, without a neck, periphysate. In section ascomata 200–300 μm diam., ± globose to ovoid; peridium composed of several layers of flattened ± hyaline thin-walled cells to 22 µm diam., varying in surface view between globose and angular, the wall thickened around the ostiole and the cells mid-brown. Interascal tissue composed of simple paraphyses, shorter than the asci, to 10 μm diam., very thin-walled, irregular, constricted at the septa, branched, tapering towards the apex. Asci 105–150 × 18–27 μm, cylindric-saccate, fairly short-stalked, the apex obtuse to rounded, very thin-walled at all stages, with a small apical ring 2–2.5 μm diam. and ca 1·5 μm thick that does not blue in iodine, 8-spored. Ascospores arranged usually obliquely uniseriately, 15·5–19 × 8·5–11 μm at maturity, at first ellipsoidal, increasing in size significantly and becoming cylindrical to cylindric-ellipsoidal, the ends rounded, hyaline, aseptate, thin-walled, smooth, without a gelatinous sheath or appendages.