Anthracocystis operculata (Vánky, C. Vánky & R.G. Shivas) McTaggart & R.G. Shivas


Sporisorium operculatum Vánky, C. Vánky & R.G. Shivas


Sori destroying the entire raceme, elongate-cylindrical, c. 15–20 mm long and 1 mm wide, enclosed by the terminal leaf sheath and covered by a thick brown peridium that ruptures irregularly exposing the blackish brown granular-powdery mass of spore balls surrounding a long filiform columella.

Spore balls globose, ellipsoidal, elongate to slightly irregular, 35–60 × (25–) 30–50 µm, dark reddish brown to subopaque, composed of 15–50(?) spores that separate by pressure.

Spores subglobose, ellipsoidal to subpolyhedrally irregular, 10.5–16.0 (–17) × 9.5–13.5 µm, yellowish to dark reddish brown; wall of the inner spores uniformly c. 0.5 µm thick, finely and densely punctate-verruculose; wall of outer spores unevenly thick, 0.8–1.5 µm, thickest at the angles and on the free coarsely verrucose-echinulate surface. On the free surface, a thin narrow pale ring, 5.0–6.5 µm diam., surrounding the thicker spore wall [3–4 (–5) µm] which is pushed outward like a plug or lid (operculum) when the spores are rehydrated.

Sterile cells not seen.

Host family: Poaceae
Host species: Mnesithea formosa (R.Br.) de Koning & Sosef


States & Territories: QLD