Sporisorium tenue (Syd. & P. Syd.) Vánky

Synonyms

Sphacelotheca amphilophis Syd.
Sphacelotheca bothriochloae Zundel (as "botriochloae")
Sphacelotheca macalpinae Zundel
Sphacelotheca tenuis (Syd. & P. Syd.) Zundel
Sporisorium amphilophis (Syd.) Langdon & Full.
Ustilago tenuis Syd. & P. Syd.

Description

Sori destroying the entire inflorescence, long-linear, 10–70 mm long, partly hidden by the uppermost leaf sheath, at first covered by a yellowish brown peridium that flakes away exposing the dark brown semi-agglutinated to powdery mass of spores mixed with sterile cells surrounding a well-developed simple or branched columella.

Spore balls ephemeral.

Spores when mature solitary, globose, subglobose, ovoid, ellipsoidal to rounded, subpolyhedrally irregular, 6.5–9.5 × 5.5–8.0 (–9) µm, yellowish brown; wall uniformly c. 0.5 µm thick, from apparently smooth to finely punctate or verrucose-echinulate; spore profile smooth, wavy to finely serrulate.

Sterile cells in irregular groups; individual cells globose, ellipsoidal to irregular, 6–15 µm long, hyaline, collapsed in old specimens; wall uniformly c. 0.8 µm thick, smooth.

Hosts
   
Host family: Poaceae
   
Host species: Bothriochloa biloba S.T.Blake
Bothriochloa bladhii (Retz.) S.T.Blake
Bothriochloa decipiens (Hackel) C.E.Hubb.
Bothriochloa decipiens var. cloncurrensis (Domin) C.E.Hubb.
Bothriochloa ewartiana (Domin) C.E.Hubb.
Bothriochloa macra (Steud.) S.T.Blake

Distribution

States & Territories: ACT, NSW, QLD, SA, VIC

Comments

The sori of S. tenue destroy the entire inflorescence. Thus, it is similar to S. andropogonis and S. doidgeae which also infect Bothriochloa and Dichanthium. However, the spores of S. tenue are mostly smaller (mean 7.5 µm) than those of the other two species (mean 9.0 µm). There are intermediate forms, particularly on Bothriochloa decipiens.