Macalpinomyces viridans R.G. Shivas, McTaggart & Vánky

Description

Sori in some spikelets of an inflorescence, transforming the inner floral organs into a spherical body 1–3 mm diam., covered by a thin initially green, later pale brown peridium of fungal and host origin, rarely with a short acute tip, occasionally with remnants of sterile anthers and tips of inner floral envelopes. At maturity the peridium ruptures irregularly to expose the dark brown powdery spore mass mixed with groups of sterile cells, surrounding a short blunt columella.

Spores globose, subglobose or ellipsoidal, 9.0–13.5 × 9–12 µm, yellowish brown; wall uniformly c. 1.5 µm thick, including the sparse 0.8–1.2 µm high spines; spore profile serrate; in SEM spines compact, spore surface between the spines finely and densely verrucose.

Sterile cells in groups; individual cells globose, subglobose to polyhedral-irregular, 5.5–10.5 × 5.0–9.5 µm, hyaline; wall uniformly c. 0.5 µm thick, smooth.

Hosts
   
Host family: Poaceae
   
Host species: Sporobolus actinocladus (F.Muell.) F.Muell.

Distribution

States & Territories: WA

Comments

Four species of Macalpinomyces are known to infect Sporobolus worldwide (Shivas et al., 2007), and two, M. spermophorus and M. viridans, occur in Australia. All species of Macalpinomyces on Sporobolus have small globose or ellipsoidal sori (a few millimetres in diameter) in some spikelets of an inflorescence.