Anthracocystis urelytri (L. Ling) T. Denchev & Denchev, 2016

Denchev, Teodor T. & Denchev, Cvetomir M., 2016, Anthracocystis rhytachnes-rottboellioidis and A. urelytri, two new combinations of smut fungi (Ustilaginales) from Africa, Phytotaxa 253 (3), pp. 227-231 : 229-230

Anthracocystis urelytri (L. Ling) T. Denchev & Denchev , comb. nov. ( Figs 9–12 )

Index Fungorum number: IF551931

Basionym: — Sorosporium urelytri L. Ling, Sydowia 7: 156, 1953.

Syn.: — Sporisorium urelytri (L. Ling) Vánky, Mycotaxon 85: 60, 2003.

Type: —On Urelytrum giganteum , SUDAN, Mendi-Yei boundary, near Olo River, 4 May 1938, J. G. Myers 9003 ( IMI 25 276, holotype, n.v.).

Sori in both fertile (sessile) and sterile (pedicellate) spikelets, cylindric or bacilliform, 3–5 × 1–1.5 mm, partly concealed by the floral envelopes; covered by a thin, yellow-brown or grayish brown peridium. The peridium ruptures irregularly, exposing the semi-agglutinated, blackish brown mass of spore balls and spores, surrounding a single, flagelliform columella with shallow longitudinal furrows and usually with short apical branches. Later, the columella extends, reaching 8 mm. Spore balls broadly ellipsoidal, subglobose, irregular or ellipsoidal, sometimes elongated, 35–85(–100) × 30–65(–80) μm, dark reddish brown, composed of tens, easily separating spores. Sterile cells absent. Spores slightly dimorphic, subglobose, broadly ellipsoidal, ellipsoidal or kidney-shaped, usually irregular, (10–)10.5–14(–15.5) × (9–)9.5–13(–14) (12.4 ± 0.9 × 11.1 ± 0.8) μm (n = 100); wall slightly uneven, often with one or few thinner areas in which the wall is collapsed and usually with lighter colour. Outer spores medium reddish brown; wall 0.8–1.1(–1.3) μm thick, smooth or minutely verruculose, spore profile not affected; inner spores light to medium yellow-brown; wall 0.5–0.8 μm thick, smooth.

Specimen examined: —On Urelytrum giganteum Pilg. : DEMOCRATIC REPUBLIC OF THE CONGO, Orientale Province, (?) Manda, 03°39′N, 27°42′E, June 1921, leg. Claessens 860 ( BR 49841,80).

Known host and distribution: —On Poaceae : Urelytrum giganteum , U. digitatum K. Schum. ( U. stapfianum C.E. Hubb. ); Africa ( Angola, Democratic Republic of the Congo, and Sudan) ( Ling 1953, Zambettakis 1971, Vánky 2003, Vánky et al. 2011).

The species of Anthracocystis on Rhytachne and Urelytrum may be distinguished by the following key:

1 Sori in ovaries; spores 7–13.5 μm long. [Currently known on Rhytachne rottboellioides ] ................... A. rhytachnes-rottboellioidis

1* Sori elsewhere; spores larger..............................................................................................................................................................2

2 Sori destroying the inflorescence. [Currently known on Rhytachne triaristata ] ........................................................... A. rhytachnes

2* Sori restricted to the spikelets. [Currently known on Urelytrum giganteum , U. digitatum ] ............................................... A. urelytri

Figures

FIGURES 9–12. Anthracocystis urelytri on Urelytrum giganteum from the Democratic Republic of the Congo (BR 49841,80). 9. Habit. Arrow indicates a single, flagelliform columella with short apical branches. 10–12. Spore balls and spores in LM. Arrows in Fig. 12 indicate inner spores. Scale bars: 9 = 0.5 cm, 10–12 = 10 μm.