Ustilago xerochloae Vánky & R.G. Shivas

Description

Sori as globose elongate or irregular swellings on the upper part of the culms, at the nodes, and also in the spikelets of some of the unit inflorescences, 2–10 mm long, 2–4 mm wide, at first covered by a thin grey to yellowish brown peridium of host and fungus origin which ruptures irregularly exposing a blackish brown semi-agglutinated to powdery mass of spores.

Spores subglobose, broadly ellipsoidal, ovoid to subpolyhedrally irregular, 8.0–12.5 × 7.5–10.5 µm, yellowish to reddish brown; wall uniformly c. 0.8 µm thick, finely and moderately densely echinulate, in SEM very finely and densely verruculose between the 0.3–0.4 µm long spines. Fungal cells of the peridium globose, broadly ellipsoidal to subpolyhedrally irregular, 5–11 × 4–8 µm, hyaline; contents homogenous; wall thin, c. 0.5 µm, smooth.

Hosts
   
Host family: Poaceae
   
Host species: Xerochloa barbata R.Br.
Xerochloa imberbis R.Br.
Xerochloa laniflora F. Muell. ex Benth.
Xerochloa sp.

Distribution

States & Territories: QLD, WA

Comments

Ustilago xerochloae has been found together with T. xerochloae and S. xerofasciculatum, sometimes occurring on the same plant and even occupying the same inflorescence. It has been collected more frequently and appears to be more widespread than either of the other two species.