Langdonia confusa (H.S. Jacks.) McTaggart & R.G. Shivas

Synonyms

Sorosporium confusum H.S. Jacks.
Sporisorium confusum (H.S. Jacks.) Vánky

Description

Sori in the ovaries, elongate, with acute tips, 1.5–4.0 mm long, 0.5–1.5 mm wide, enclosed by the enveloping glumes, covered by the pericarp which ruptures at maturity exposing the blackish brown granular-powdery mass of spore balls.

Spore balls subglobose, ovoid, ellipsoidal, elongate or irregular, 40–100 × 30–70 µm, reddish brown, composed of 15–80 (or more?) spores that separate readily by pressure.

Spores slightly dimorphic, subpolyhedrally irregular, rarely ellipsoidal, 10–15 × 9.0–12.5 µm, yellowish brown; inner spores more angular, slightly paler; wall even or nearly so, 0.5–1.0 (–1.5) µm thick; inner spores sparsely, outer spores densely verrucose-echinulate, the warts up to 0.5 µm high; spore profile of the free surface finely serrulate.

Sterile cells absent.

Spore germination (after 24 hr on water-agar at room temperature) of Ustilago-type, with a septate basidium bearing lateral and terminal basidiospores and lateral hyphal branches.

Hosts
   
Host family: Poaceae
   
Host species: Aristida behriana F.Muell.
Aristida benthamii Henrard
Aristida calycina R.Br.
Aristida calycina var. praealta Domin
Aristida holathera Domin
Aristida inaequiglumis Domin
Aristida ingrata Domin
Aristida jerichoensis (Domin) Henrard var. jerichoensis
Aristida jerichoensis var. subspinulifera Henrard
Aristida muricata Henrard
Aristida pruinosa Domin
Aristida queenslandica Henrard
Aristida ramosa R.Br.
Aristida vagans Cav.
Aristida warburgii Mez

Distribution

States & Territories: NSW, NT, QLD

Comments

Langdonia confusa is one of four species of Langdonia known from Aristida in Australia. This species and L. aristidae are often difficult to separate and show no differences macroscopically and in host symptoms. Although the spores of A. confusa are 9–15 µm long and more distinctly ornamented than those of L. aristidae (spores 6.5–10.5 µm), intermediate forms were often seen. It is possible that L. confusa and L. aristidae represent a complex of species. For example, the spores of L. confusa were consistently larger on specimens of Aristida queenslandica. Molecular studies may help to resolve matters.