Sporisorium aegyptiacum (A.A. Fisch. Waldh.) Vánky

Synonyms

Ustilago aegyptiaca A.A. Fisch. Waldh.
Ustilago schismi Bubák

Description

Sori in the spikelets destroying the innermost floral organs, leaving the glumes and the distal part of the inner floral envelopes intact, c. 2–3 mm long and 1 mm wide, hidden by the glumes, at first covered by a yellowish brown peridium that ruptures irregularly from its basal part, flakes away together with the intact distal part of the floral envelopes, exposing the dark brown powdery mass of spores and sterile cells surrounding a 2–3 mm long simple central columella that sometimes has short lateral branches. Infection systemic; all spikelets of a plant infected; diseased plants stunted.

Spores solitary at maturity, subglobose, ellipsoidal to slightly irregular, 10.5–14.5 × 9–12 µm, often flattened (6.5–8.0 µm wide), yellowish brown; wall uniformly 0.8 µm thick, densely and finely echinulate; spore profile ±smooth to finely serrulate.

Sterile cells in irregular groups or chains, or solitary, subglobose, ellipsoidal, elongate or slightly irregular, 5.0–10.5 × 5.0–6.5 µm, hyaline; contents homogenous; wall c. 0.5 µm thick, smooth.

Hosts
   
Host family: Poaceae
   
Host species: Schismus barbatus (L.) Tell.

Distribution

States & Territories: NSW, SA, VIC

Comments

The sori of S. aegyptiacum are inconspicuous as they are hidden by the glumes. This may explain why this smut has rarely been collected even though its introduced host, Schismus barbatus, is widespread across southern Australia. Sporisorium aegyptiacum has not yet been collected on Schismus arabicus in Australia.