Sporisorium panici (E. Mackinnon) Vánky

Synonyms

Sorosporium panici E. Mackinnon
Ustilago clelandii Syd.
Ustilago panici-gracilis E. Mackinnon

Description

Sori destroying the entire inflorescence including the distal part of the shoot with shortened internodes, also occupying the basal swollen part of the distal leaves or in all spikelets of an inflorescence, ±completely destroying the inner floral organs and the basal part of the inner floral envelopes which appear bullate (similar to sori of Ustilago bromivora), partly enclosed by the intact glumes. Sori elongate, cylindrical and irregularly bullate, with the distal parts of the leaves intact, 2–15 mm long, 1.5–4.0 mm wide, including the acute tip, the remnants of the inner floral envelopes, covered by a thin greyish peridium that ruptures irregularly exposing the blackish brown powdery spore masses surrounding a stout central columella with short lateral branches. Spore mass composed of large loose many-spored balls that disintegrate in mature sori.

Spores subpolyhedrally irregular or ellipsoidal, 9.5–14.0 (–16) × 8.0–10.5 (–12) µm, yellowish brown; wall uniformly 0.5–1.0 µm thick, moderately densely and finely echinulate; in SEM finely verrucose between the spines; spore profile in LM serrulate.

Sterile cells not seen.

Hosts
   
Host family: Poaceae
   
Host species: Paspalidium caespitosum C.E.Hubb.
Paspalidium constrictum (Domin) C.E.Hubb.
Paspalidium criniforme S.T.Blake
Paspalidium gracile (R.Br.) Hughes
Paspalidium jubiflorum (Trin.) Hughes

Distribution

States & Territories: NSW, QLD

Comments

Sporisorium panici and Ustilago panici-gracilis were collected by Ewen Mackinnon from Nygan Experiment Farm, New South Wales in 1911 and described in the following year. The principal difference between the two was that S. panici was restricted to the host florets while U. panici-gracilis destroyed the entire inflorescence. However, subsequent collections of infected Paspalidium included intermediate forms in which the sori destroyed groups of florests or only part of the inflorescence. Because all other morphological characteristics are ±identical in Mackinnon’s two taxa, and the sori always have a short stout columella, we have accepted Sporisorium panici as the more appropriate name for this smut.