Cintractia axicola (Berk.) Cornu

Synonyms

Anthracoidea suedae (Sawada ex S. Ito) Vánky
Cintractia pilulifera Y. Ling & T.L. Chen
Cintractia fimbristylis-kagiensis Sawada ex S. Ito
Cintractia fimbristylis-kagiensis var. fukienensis Y. Ling & T.L. Chen
Cintractia mundkurii S. Chowdhury
Cintractia peribebuyensis (Speg.) Sawada
Cintractia peribebuyensis (Speg.) Speg.
Cintractia peribebuyensis var. major Pavgi & Mundk.
Cintractia suedae Sawada ex S. Ito
Ustilago axicola Berk.
Ustilago fimbristylis Thüm.
Ustilago peribebuyensis Speg.

Description

Sori surrounding the base of the floral pedicels, occasionally the flowers, subglobose to ovoid, 1–5 mm long, 1–2 mm wide, at first covered by a white-greyish (later brown) sterile fungal peridium that flakes away to expose the black agglutinated spore mass developed in pockets of a hyaline stroma.

Spores solitary, globose, ovoid to subpolyangular, usually compressed laterally, 12–18 × 8–15 µm, reddish brown; wall c. 1 µm thick, thinner and paler on the flattened sides, in LM smooth to indistinctly pitted, or faintly ornamented with short fine sinuous striae, in SEM very finely and densely verruculose, the warts partly confluent, forming short irregular sometimes ramified striae.

Spore germination resulting in 4-celled basidia; basidial cells uninucleate, with haploid basidiospores budding from basidial cells; basidiospores fusing in pairs initiating the dikaryophase. Two of the basidial cells sometimes fusing to form dikaryotic hypha. Infection localised. Dikaryotic hyphae penetrating the epidermal cells of the host, spreading inter- and intracellularly and invading the epidermis, cortex, medulla, phloem and the lignified cells of the infected peduncle. White fungal sheath formed of mononucleate cells developing around the peduncle 7–10 days after infection. Under this sheath, the binucleate mycelium differentiating into stromatal tissue and sporogenous pockets. Cells of dikaryotic hyphae in the inner part of sporogenous pockets dividing, giving rise to rows of spore initials that mature successively.

Hosts
   
Host family: Cyperaceae
   
Host species: Fimbristylis dichotoma (L.) Vahl

Distribution

States & Territories: NT, NSW, QLD, WA

Comments

Australian herbarium specimens of this smut fungus that had been identified on other species of Fimbristylis and Cyperus were found to generally refer to Cintractia mitchellii and C. limitata, respectively. Cintractia axicola forms sori mostly around the floral pedicels, whereas C. mitchellii produces sori in the spikelets. The spores of C. axicola tend to be more variable in size (8–18 µm) than those of C. mitchellii (10.0–14.5 µm).