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

Description

Sori in all spikelets of an inflorescence, destroying the innermost floral organs, narrowly ellipsoidal, 2.0–2.5 mm long, 1.0–1.5 mm, ±hidden by the intact floral envelopes, covered by a thick pale brown peridium that ruptures from its apex exposing the blackish brown powdery mass of loose spore balls, spores and sterile cells surrounding a short simple central columella.

Spore balls subglobose, ellipsoidal or irregular, 50–120 × 40–90 µm, dark reddish brown to opaque, composed of very many readily separating spores.

Spores subglobose, ovoid to slightly irregular, 9.5–13.5 × 9–13 µm, reddish brown; wall slightly unevenly thick, c. 1 µm, densely and prominently echinulate; spore profile serrulate.

Sterile cells few, solitary or in small groups.

Hosts
   
Host family: Poaceae
   
Host species: Digitaria gibbosa (R.Br.) P.Beauv.

Distribution

States & Territories: QLD

Comments

Sporisorium gibbosum is one of two smut fungi that occur on Digitaria gibbosa in Australia. The other, Macalpinomyces digitariae, has sori in some of the ovaries, these lacking columellae and with smaller spores (8–14 × 7–13 µm).