Pyrenophora polytricha

A minute ascomycete occurring on decaying grass culms on the ground, with globose, black perithecia featuring a very hirsute surface covered with thick bristle-like setae, and measuring only 0.25 to 0.50 mm in diameter.

Anamorph belonging to the genus Drechslera, with simple, unbranched, septate, brown conidiophores, geniculate towards the apex, 8 to 11 µm wide.

Conidia cylindrical with rounded ends, with 4 to 8 transverse septa depending on maturity, 75 to 105 µm long, 13 to 17 µm wide, containing abundant brownish-olivaceous intracellular pigment.

Teleomorph with an outer peridium of polyhedral to angular cells 10 to 25 µm long and 8 to 20 µm wide, filled with blackish intracellular pigment, subtended by identical but hyaline cells.

External setae rigid, black, thick-walled, 150 to 240 µm long and averaging 6 to 10 µm in width.

Asci cylindrical to clavate, 8-spored, bitunicate, 190 to 245 µm long, 35 to 45 µm wide, uniseriate to obliquely uniseriate (slightly overlapping), inamyloid in Melzer's reagent.

Ascospores cylindrical-ellipsoidal to oblong with rounded ends, yellowish-green under the microscope with paler hyaline apices, 50 to 65 µm long, 20 to 26 µm wide, with five transverse septa and one to three longitudinal septa (muriform).