Sporisorium anadelphiae-trichaetae T. Denchev & Denchev, 2016

Denchev, Teodor T. & Denchev, Cvetomir M., 2016, Jamesdicksonia anadelphiae-trichaetae (Georgefischeriales) and Sporisorium anadelphiae-trichaetae (Ustilaginales), new species on Anadelphia trichaeta (Poaceae) from Guinea, Phytotaxa 252 (3), pp. 205-216 : 211-213

Sporisorium anadelphiae-trichaetae T. Denchev & Denchev , sp. nov. ( Figs 35–44 )

Index Fungorum number: IF551711

Type: —On Anadelphia trichaeta (Reznik) Clayton ( Poaceae ). GUINEA. Labé Region: Labé, Bowal Guessé, 26 October 1956, leg. J. G. Adam 30 832 ( B 70 0016203, holotype).

Diagnosis: — Sporisorium anadelphiae-trichaetae differs from S. monocymbii by having spore walls with higher ornaments (spines up to 0.7 μm high versus spinules up to 0.3(–0.4) μm high for S. monocymbii ). The spores of S. anadelphiae-trichaetae are larger than that of S. monocymbii .

Etymology: —Epithet derived from the host plant, Anadelphia trichaeta .

Sori in all fertile spikelets of the inflorescence, 0.7–1.2 × 0.2–0.4 mm, ovoid or fusiform, concealed by the spatheoles, later the spatheoles spreading slightly; initially covered by a thick dark brown peridium that soon ruptures irregularly, exposing a single, stout, tapering, not branching columella, reaching up to 2.5 mm in length. Columella with shallow longitudinal furrows, surrounded by a powdery blackish brown mass of spores and sterile cells. Sterile cells single or in small irregular groups, subglobose, ovoid, broadly ellipsoidal, slightly irregular, often collapsed, 8.5–15(– 16.5) μm long, subhyaline to light yellow brown, wall 0.6–1.0 μm thick, smooth. Spores subglobose, globose, broadly ellipsoidal or ovoid, (8.5–)9–11.5(–12.5) × (8–)8.5–11(–12) (10.5 ± 0.7 × 9.6 ± 0.7) μm (n = 250), medium reddish brown, wall evenly thickened, 0.6–1.0 μm thick, moderately echinulate, spore profile affected. In SEM moderately echinulate, spines up to 0.7 μm high; surface between the spines densely punctate.

Known host and distribution: —On Poaceae : Anadelphia trichaeta , Africa ( Guinea) (Fig. 11). Known only from the type collection.

Comments: — Sporisorium anadelphiae-trichaetae differs from S. monocymbii by having spore walls with higher ornaments (spines up to 0.7 μm high versus spinules up to 0.3(–0.4) μm high for S. monocymbii ). The spores of S. anadelphiae-trichaetae are larger than that of S. monocymbii —(8.5–)9–11.5(–12.5) μm long versus (7–)7.5– 10.5(–11.5) μm long for S. monocymbii . The mean values of the spore length and width of these species are discrete (10.5 ± 0.7 × 9.6 ± 0.7 μm versus 9.1 ± 0.6 × 8.1 ± 0.5 μm for S. monocymbii ). Further, the sori of S. anadelphiae-trichaetae are confined to spikelets while in the case of S. monocymbii , one sorus may often comprise a group of spikelets.

Sporisorium anadelphiae-trichaetae can easily be differentiated from Anthracocystis anadelphiae by the absence of spore balls and presence of sterile cells. The spores of A. anadelphiae are dimorphic, with outer spores (9.5–)10.5–15(–16) μm long, while the spores of S. anadelphiae-trichaetae are not dimorphic, (8.5–)9–11.5(–12.5) μm long.

This is an inconspicuous smut fungus, especially in the early stages of development when the sori are completely concealed by the glumes ( Figs 35, 36 ). Even at maturity, when the sori are fully developed, the infection is very difficult to detect without a stereomicroscope. A useful sign for detecting the presence of this smut fungus is the absence of typical for Anadelphia trichaeta principal lemma awns, which are 20–30 mm long overall, with a twisted column, 20–27 mm long ( Clayton et al. 2015) ( Fig. 38 ).

Measurements of spores from immature sori with an intact peridium (see the arrowheads on Figs 35, 36 ) should not be taken into consideration since the mean values of the spore length and width can be lower with up to 2 μm.

Specimen B 70 0021869 (originally labelled as infected by Sporisorium andropogonis ) consists of two smut fungi, Sporisorium anadelphiae-trichaetae and Jamesdicksonia anadelphiae-trichaetae , with some individual plants simultaneously infected by both of these smut fungi (Figs 14, 15).

On Elymandra :

Figures

FIGURES 35–44. Sporisorium anadelphiae-trichaetae on Anadelphia trichaeta (holotype, B 70 0016203). 35–38. Habit (arrowheads in Figs 35 and 36 indicate immature sori, black arrows in Figs 35–37 indicate mature sori, and black arrow in Fig. 38 shows lemma awn with a twisted column). 39, 40. Spores and sterile cells in LM (spores in median and surface view, respectively). Black arrows show sterile cells. 41. Spores in LM (in median view). 42–44. Spores in SEM. Scale bars: 35–38 = 0.5 cm, 39–41 = 10 μm, 42–44 = 5 μm.