Ustilago agropyri McAlpine

Synonyms

Ustilago readeri Syd. & P. Syd. ex McAlpine

Description

Sori in stems, leaves and inflorescence; in stems and leaves as short or long subepidermal pustules or bullate streaks; inflorescence completely or partly destroyed, in which case the proximal part of the floral axis is especially affected or the whole axis and the basal part of the spikelets are consumed while the distal part of the glumes remains intact. Sori at first covered by the epidermis as a silvery or lead-coloured membrane that ruptures irregularly exposing the black semi-agglutinated mass of spores.

Spores globose, subglobose, broadly ellipsoidal to slightly irregular, 9.5–13.5 × (8–) 9–12 µm, dark reddish brown; wall relatively thick (0.8–1.5 µm), with a thin pale rounded or elongate germ pore 1.5–2.5 µm diam.; surface moderately densely and finely verrucose-echinulate, scarcely affecting the spore profile.

Spore germination (on malt-yeast extract-peptone agar, at room temperature, after 1 day) resulting in 1 or 2, 2–4-celled basidia producing ellipsoidal basidiospores laterally and terminally on short sterigmata.

Hosts
   
Host family: Poaceae
   
Host species: Austrodanthonia auriculata (J.M.Black) H.P.Linder
Austrodanthonia caespitosa (Gaud.) H.P.Linder
Austrodanthonia eriantha (Lindl.) H.P.Linder
Austrodanthonia geniculata (J.M.Black) H.P.Linder
Austrodanthonia penicillata (Labill.) H.P.Linder
Austrodanthonia pilosa (R.Br.) H.P.Linder
Austrodanthonia racemosa (R.Br.) H.P.Linder
Notodanthonia semiannularis (Labill.) Zotov

Distribution

States & Territories: ACT, NSW, SA, TAS, VIC, WA

Comments

Two smut fungi, U. agropyri and U. comburens, occur on Austrodanthonia in Australia. The former has sori that are initially covered by a thin, silvery membrane while the latter has naked sori.