Anthracocystis walkeri (Vánky) McTaggart & R.G. Shivas

Synonyms

Sporisorium walkeri Vánky

Description

Sori destroying the central and often also the involucral spikelets of the raceme, cylindrical, c. 8–12 mm long and 1 mm wide, at first covered by a yellowish brown peridium that ruptures longitudinally exposing the black, initially agglutinated, later granular-powdery mass of spore balls and several long filiform columellae of host origin. Peridium composed of tightly packed rows of hyaline elongate subtetrangular fungal cells 5.5–20.0 × 4.0–6.5 µm.

Spore balls subglobose, ovoid, elongate or irregular, (30–) 40–80 × (25–) 30–70 µm, dark reddish brown, opaque, rather permanent, composed of a few dozen to > 100 spores.

Spores subglobose to ellipsoidal. Inner spores sometimes subpolyhedrally irregular, 8–14 × 7–11 µm, dark reddish brown. Outer spores with a slightly unevenly thickened wall; free surface thinner, 0.5–1.0 µm, punctate-verruculose, rarely finely echinulate; contact sides often thicker [1.0–1.5 (–2.5) µm], finely punctate to apparently smooth, like those of inner spores.

Hosts
   
Host family: Poaceae
   
Host species: Themeda triandra Forssk.

Distribution

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

Comments

Anthracocystis walkeri was treated by McAlpine (1910) under the name Tolyposporium bursum (Berk.) McAlpine [= Macalpinomyces bursus (Berk.) Vánky] which represents another smut. This species infects spikelets or the entire raceme, and the (lemma) awns of the fertile spikelets are usually destroyed. This distinguishes it from A. anthistiriae which infects the ovaries but leaves the awns of fertile spikelets intact.