Macalpinomyces digitariae Vánky & R.G. Shivas

Description

Sori in some ovaries of an inflorescence, inconspicuous, ovoid, with a short acute tip, 1.0–1.5 mm long, 0.5–0.7 mm wide, ±hidden by the floral envelopes, at first covered by a thin pale brown peridium that ruptures irregularly exposing the dark brown semi-agglutinated to granular-powdery mass of spores mixed with sterile cells.

Spores solitary or in irregular groups, subglobose, ovoid, ellipsoidal to usually subpolyhedrally slightly irregular, 7.5–12.0 × 7.0–9.5 µm, yellowish brown; wall uniformly 0.5–0.8 µm thick, finely and rather densely echinulate; spore profile ±smooth to finely serrulate.

Sterile cells solitary or in irregular groups, ovoid, ellipsoidal to subpolyhedrally irregular, the same size or larger than the spores, 8–14 × 7–13 µm, pale yellowish brown; wall 1.0–1.5 (–2.0) µm thick, smooth.

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

Distribution

States & Territories: NT

Comments

Macalpinomyces digitariae is one of two smut fungi that occur on Digitaria gibbosa in Australia. The other, Sporisorium gibbosum, has sori in all spikelets of the inflorescence, as well as a columella and larger spores (9.5–13.5 × 9–13 µm).