Sporisorium inayati (Syd. & P. Syd. & Butler) Vánky

Synonyms

Sphacelotheca inayati (Syd. & P. Syd. & Butler) Mundk. & Thirum.
Ustilago inayati Syd. & P. Syd. & Butler

Description

Sori in the spikelets of a few racemes in the inflorescence, often affecting all four involucral spikelets of a raceme and usually leaving intact the central spikelet (awn present), ovoid to cylindrical, c. 2–3 mm long and 1 mm wide, covered by a thick light brown peridium that dehisces early exposing the dark brown powdery mass of spore balls and spores mixed with sterile cells and a short often shortly branched central columella.

Spore balls many-spored, loose, subglobose, elongate to irregular, readily disintegrating into solitary spores. Spores globose, subglobose to ovoid, (8–) 9–12 (–13) × 8.0–10.5 (–11) µm, reddish brown; wall uniformly c. 1 µm thick, densely and prominently echinulate.

Sterile cells solitary or in irregular groups, subglobose, ellipsoidal, hemiglobose to irregular, 8–15 µm long, subhyaline to pale yellowish brown; wall c. 1 µm thick, smooth.

Hosts
   
Host family: Poaceae
   
Host species: Iseilema membranaceum (Lindley) Domin
Iseilema vaginiflorum Domin

Distribution

States & Territories: NSW, NT, QLD

Comments

Sporisorium inayati is one of four species of Sporisorium that infect Iseilema in Australia. It produces sori in some of the spikelets in a raceme, often leaving the central spikelet with its awn intact. The location of the sori of S. inayati in the spikelets of a few racemes distinguishes it from the two endemic species, S. mitchellii and S. iseilematis-vaginiflori, as well as from the exotic S. iseilematis (Syd., P.Syd. & E.J.Butler) Vánky (type on Iseilema laxum, India), all of which infect the entire racemes.

Sporisorium inayati has spores similar in size and shape to those of S. mitchellii. By contrast, S. iseilematis-vaginiflori has larger spores (10.5–17.5 µm), including many that are ellipsoidal or elongate. The spores of S. inayati are larger and the columellae shorter than those of S. iseilematis which has spores less than 10 µm long and columellae up to 15 mm.