Sporisorium capillipedii-alpini T. Denchev & Denchev, 2016

Denchev, Teodor T., Sun, Hang, Denchev, Cvetomir M. & Boufford, David E., 2016, A new smut fungus on a new grass: Sporisorium capillipedii-alpini (Ustilaginales) sp. nov. infecting Capillipedium alpinum (Poaceae) sp. nov., from Sichuan, China, Phytotaxa 252 (3), pp. 217-227 : 220-222

Sporisorium capillipedii-alpini T. Denchev & Denchev , sp. nov. ( Figs 4–11 )

Index Fungorum number: IF551695

Type: —On Capillipedium alpinum H. Sun & Boufford ( Poaceae ). CHINA. Sichuan Province: Xiangcheng Xian, Xiarewu, on road between Xiangcheng and Daxue Shan (road to Zhongdian from Xiangcheng), spinescent shrub community on dry, stony slopes above Souqu River, 28°47′32″N, 99°50′14″E, 2700 m, 22 July 1998, leg. D. E. Boufford, B. Bartholomew, W. Y. Chen, M. J. Donoghue, R. H. Ree, H. Sun & S. K. Wu 29019 ( BRIP 63 636, holotype).

Diagnosis: — Sporisorium capillipedii-alpini differs from the species of Sporisorium that infect Capillipedium, Botriochloa , and Dichanthium and destroy all spikelets of the inflorescence, as follows: from Sporisorium taianum by having larger spores with minutely echinulate spore walls, from S. dichanthicola by having larger spores, from S. sahayae by having lower spore wall ornamentation and thinner spore walls, from S. andropogonis-annulati by having larger spores and smaller sterile cells with thinner walls, and from S. mysorense by possessing minutely echinulate spore walls and differently colored spores (medium yellow-brown with purplish tint) and sterile cells (hyaline).

Etymology: —Epithet derived from the host plant, Capillipedium alpinum .

Sori in all spikelets (sterile and fertile) of the inflorescence, 1.2–2.5 × 0.4–0.8 mm, ellipsoidal or fusiform, partially visible between the spreading glumes; initially covered by a thick, yellow-brown peridium that soon ruptures irregularly, exposing a single, stout, tapering, sometimes with a few short branches, columella as long as the sorus and with shallow longitudinal furrows, surrounded by a powdery, blackish brown mass of spores and sterile cells. Sterile cells in irregular groups, single sterile cells uncommon; globose, subglobose, broadly ellipsoidal or irregular, often collapsed, (6–)7.5–12(–14.5) μm long, usually smaller than the spores, hyaline; wall 0.5–0.8 μm thick, smooth. Spores subglobose, broadly ellipsoidal, slightly irregular, globose, ovoid or sometimes ellipsoidal, (10.5–)11.5–14.5(–15.5) × (9.5–)10.5–13(–14) (12.7 ± 0.8 × 11.5 ± 0.7) μm (n/ 2 = 300), medium yellow-brown with purplish tint; wall more or less evenly thickened, 0.6–0.9 μm thick, in LM minutely verruculose, spore profile not affected or slightly affected. In SEM sparsely minutely echinulate, spinules up to 0.2 μm high, spore surface punctate between the spinules.

Known host and distribution: —On Poaceae : Capillipedium alpinum , Asia ( China, Sichuan) (Fig. 26).

Additional specimen examined: —On Capillipedium alpinum . CHINA. Sichuan Province: Xiangcheng Xian, Reda, vicinity of the town of Reda, dry slopes with cut over forest of Quercus , Pinus , Berberis , Cotoneaster , 29°6′11″N, 99°37′55″E, 3450–3650 m, 15 July 1998, leg. D.E. Boufford, B. Bartholomew, W.Y. Chen, M.J. Donoghue, R.H. Ree, H. Sun & S.K. Wu 28703 (BRIP 63 637, paratype).

Comments: — Sporisorium capillipedii-alpini can be distinguished from the other species of Sporisorium that destroy all spikelets of the inflorescence of an infected plant of Capillipedium, Botriochloa , and Dichanthium . From S. taianum (Syd.) L. Guo , it differs by having larger spores, (10.5–)11.5–14.5(–15.5) μm long with minutely echinulate spore walls; S. taianum possesses smooth spores 6.5–8 μm long.

Sporisorium dichanthiicola (Mundk. & Thirum.) Vánky can also be differentiated by its smaller spores (5.5–9 μm long).

Sporisorium capillipedii-alpini differs from S. sahayae by having lower spore wall ornamentation (with spinules up to 0.2 μm high while the spines of S. sahayae are up to 0.4(–0.6) μm high) and thinner spore walls (0.6–0.9 μm thick versus 0.7–1.4(–1.7) μm thick for S. sahayae ), and from S. andropogonis-annulati by having larger spores ((10.5–)11.5–14.5(–15.5) μm long versus (8.5–)9–12(–13) μm long for S. andropogonis-annulati ) and smaller sterile cells with thinner walls (6–14.5 μm long, with walls 0.5–0.8 μm thick versus sterile cells 9–22 μm long, with walls 0.8–2.0(–2.5) μm thick).

Sporisorium capillipedii-alpini is distinguished from S. mysorense by having a different type of spore wall ornamentation (minutely echinulate, with spinules up to 0.2 μm high; the spore walls of S. mysorense are punctate, with projections up to 0.1 μm high) and differently colored spores (medium yellow-brown with purplish tint versus medium reddish brown) and sterile cells (hyaline versus subhyaline to light yellow-brown). Additionally, S. capillipedii-alpini possesses slightly larger spores, (10.5–)11.5–14.5(–15.5) (12.7 ± 0.8) μm long versus (9–)10–12.5(–13.5) (11.3 ± 0.7) μm long for S. mysorense .

Six species of Sporisorium infecting Capillipedium, Botriochloa , and Dichanthium have been previously reported from China: S. andropogonis , S. andropogonis-annulati , S. doidgeae , S. reticulatum , S. spinulosum , and S. taianum ( Sydow 1929, Ling 1945, 1953, Ling & Chen 1945, Wang 1963, Liu et al. 1979, Guo 1990, 2000, 2011, Wang & Piepenbring 2002, Vánky 2004, He & Guo 2009). Sporisorium andropogonis , S. doidgeae , S. reticulatum , and S. spinulosum destroy the whole inflorescence, and not just all spikelets within the inflorescence, and, as mentioned above, can easily be distinguished from S. capillipedii-alpini . The other two species, S. capillipedii (L. Ling) L. Guo and S. andropogonis-micranthi (L. Ling & T.L. Chen) Vánky —both on Capillipedium parviflorum (R. Br.) Stapf — were described from China (Ling 1945, Ling & Chen 1945) but were reduced to synonyms of S. doidgeae ( Vánky 2004) .

Figures

FIGURES 4–11. Sporisorium capillipedii-alpini T. Denchev & Denchev on Capillipedium alpinum (holotype, BRIP 63 636). 4. Habit. 5–7. Spores in LM. 5, 6. In median view. 7. In surface view. 8–11. Spores in SEM. Scale bars: 4 = 0.2 cm, 5–8 = 10 μm, 9, 10 = 5 μm, 11 = 2 μm.