Anthracocystis cymbopogonis-bombycini (R.G. Shivas & Vánky) McTaggart & R.G. Shivas

Synonyms

Sporisorium cymbopogonis-bombycini R.G. Shivas & Vánky

Description

Sori destroying the spikelets (usually every spikelet in a raceme, but only a few racemes in an inflorescence are infected), long-linear, to 15 mm long, c. 1 mm wide, partly hidden by floral envelopes and spatheoles, covered by a yellowish brown peridium that splits longitudinally at maturity into several bands, exposing the black granular-powdery mass of spore balls surrounding several filiform columellae.

Spore balls globose, ovoid, oblong to subpolyhedrally irregular, 50–125 × 40–80 µm, reddish brown to subopaque, composed of tens of spores that separate readily by pressure.

Spores globose, subglobose, ellipsoidal to rounded or subpolyhedrally irregular, dimorphic. Outer spores 9.5–14.5 × 9–13 µm, medium dark yellowish or reddish brown; wall uneven, 0.5–1.5 µm thick, with alternating thin and thicker areas, with a thin rounded area (germ pore?) in the centre of the free wall; contact sides smooth or nearly so; free surface moderately to densely punctate-verrucose; spore profile wavy to finely serrulate, in SEM warts low, variable in size, blunt or subacute. Inner spores 8.5–13.5 × 8–11 µm, pale yellowish brown, wall thin, c. 0.5 µm, even or slightly unevenly thick, smooth.

Sterile cells absent.

Hosts
   
Host family: Poaceae
   
Host species: Cymbopogon bombycinus (R.Br.) Domin

Distribution

States & Territories: WA

Comments

Of the 13 species recognised on Cymbopogon (Vánky, 2003), A. cymbopogoni-bombycini is most similar to S. compactum Vánky (type on C. giganteus Chiov., Senegal). The latter differs by having compact spore balls of firmly united spores that break rather than separate under hard pressure and sori that form witches’ brooms in the inflorescence.