Websdanea lyginiae (Websdane, Sivasith., K.W. Dixon & Pate) Vánky

Synonyms

Ustilago lyginiae Websdane, Sivasith., K.W. Dixon & Pate

Description

Sori as bullate dark reddish brown striae on the distal internodes of the culms, c. 1–50 mm long and 1 mm wide, covered by the epidermis which ruptures at maturity exposing the black granular-powdery mass of irregular loose spore balls. Swollen sori developing in longitudinal depressions in the culm, beginning from a ±narrow isthmus of sporogenous hyphae and host cells permeated by inter- and intracellular hyphae. Groups of spore balls differentiating within the basal sporogenous hyphae of young sori; during maturation these are pushed toward the periphery. When young, groups of spore balls separated into irregular lobes by fascicles of sporogenous hyphae that penetrate into the sori. During maturation, these fascicles disappear towards the periphery. Infection systemic; usually all culms of a plant affected; smutted culms sterile.

Spore balls subglobose, ovoid to usually irregularly elongate, 45–200 × 30–90 µm, dark olivaceous brown, opaque, composed of many readily separating spores.

Spores subglobose, ovoid, irregularly subpolyhedral or polyhedral, elongate, often prolonged into 1 or 2 subacute or acute tips, (6–) 7–13 (–16) × (5–) 6–9 µm, olivaceous brown; wall unevenly thick, 0.5–1.5 µm; in LM smooth; in SEM outer spores inconspicuously low-verruculose, inner spores smooth.

Spore germination resulting in (1–) 2–4-celled basidia c. (6–) 20–40 × 1.5 µm. Basidiospores fusiform or ovoid, produced successively on well-developed sterigmata, 3.5–12.0 × 1.0–1.5 µm; basidiospores budding and giving rise to smaller fusiform or ovoid cells or hyphae. Alternatively, richly branched hyphae produced on the basidia, with only a few ovoid basidiospores at the tips of short or long branches.

Hosts
   
Host family: Restionaceae
   
Host species: Lyginia barbata (Labill.) R.Br.

Distribution

States & Territories: WA

Comments

Only Lyginia barbata was recognised when Websdane et al. (1993) described this smut as Ustilago lyginiae. However, Websdanea lyginiae also occurs on L. imberbis R.Br. and L. excelsa B.G.Briggs & L.A.S.Johnson in Western Australia (Sieler et al., 1999). Websdane (1995) noted that spore morphology varied in different collections, and Vánky (1997) considered this variation to be taxonomically significant, suggesting that both Lyginia and its associated pathogens might be in an early phase of speciation.