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

Synonyms

Sporisorium paraneurachnis R.G. Shivas & Vánky

Description

Sori inconspicuous, in the shoots, always associated with witches’ brooms (i.e. small leaves, shortening of internodes, stunting of the plant and excessive proliferation of shoots), cylindrical, 3–6 mm long, 1.0–1.5 mm wide, covered by a peridium of fungal and host origin, with up to 3 leaf remnants at their apex as acute tips. At maturity, the peridium ruptures exposing the black granular-powdery mass of spore balls and several filiform columellae.

Spore balls subglobose, ovoid, elongate or irregular, 40–120 × 35–85 µm, reddish brown, composed of numerous spores that separate by pressure.

Spores subglobose, ovoid, to subpolyhedrally or polyhedrally irregular, 9–13 × 8–11 µm, reddish brown, dimorphic. Outer spores darker; wall c. 1 µm thick, finely and densely verruculose. Inner spores paler, thin-walled (c. 0.5 µm), finely and densely punctate, generally smaller and more angular.

Sterile cells rare, solitary, in small groups or in short chains, subglobose, ovoid or with flattened contact sides, 8–12 µm long, hyaline, thin-walled (0.5–1.0 µm), smooth.

Hosts
   
Host family: Poaceae
   
Host species: Paraneurachne muelleri (Hack.) S.T.Blake

Distribution

States & Territories: WA

Comments

Anthracocystis paraneurachnis, along with Ustilago neurachnis and U. tepperi, occurs on species of Poaceae in the endemic subtribe Neurachninae. It is always associated with witches’ broom.