Hypoxylon guilanense Pourmoghaddam & C. Lambert, 2020

Pourmoghaddam, Mohammad Javad, Lambert, Christopher, Surup, Frank, Khodaparast, Seyed Akbar, Krisai-Greilhuber, Irmgard, Voglmayr, Hermann & Stadler, Marc, 2020, Discovery of a new species of the Hypoxylon rubiginosum complex from Iran and antagonistic activities of Hypoxylon spp. against the Ash Dieback pathogen, Hymenoscyphus fraxineus, in dual culture, MycoKeys 66, pp. 105-133 : 105

Hypoxylon guilanense Pourmoghaddam & C. Lambert sp. nov. Fig. 2

Holotype.

Iran, Guilan Province, Rasht County, Saravan forest, 37°04'26"N, 49°38'13"E, 183 m elev., on fallen branch of Quercus castaneifolia , 9 Apr 2015, M.J. Pourmoghaddam. (GUM 989; ex-holotype culture MUCL 57726).

Etymology.

Guilanense, refers to its origin in Guilan province, Iran.

Teleomorph.

Stromata superficial, hemispherical to pulvinate, up to 2 cm long × 0.1-0.7 cm wide, with conspicuous perithecial mounds, surface Sienna (8), Umber (9) to Buff (45); Scarlet (5) to Orange (7) granules beneath the surface and between the perithecia, with Orange (7) KOH-extractable pigments. Perithecia spherical to obovoid, 0.33-0.66 high × 0.3-0.55 mm wide. Ostioles umbilicate, inconspicuous. Asci not seen. Ascospores smooth, unicellular, brown to dark brown, ellipsoid, inequilateral with narrowly rounded ends, 12-15 × 5-6 µm, with straight germ slit spore-length on convex side; perispore dehiscent in 10% KOH, conspicuous coil-like ornamentation in SEM; epispore smooth.

Cultures and anamorph.

Colonies on OA covering a 9 cm Petri dish in 4 wk, at first white, becoming Buff (45), cottony, slightly zonate with diffuse margins; finally, becoming Honey (64). Anamorph not produced in culture.

Secondary metabolites.

Orsellinic acid, rubiginosin A and an unknown isomer thereof, as well as mitorubrinol acetate as prevailing stromatal components; cultures produce yet unidentified compounds on barley-malt agar.

Notes.

The description of this taxon is based on a single specimen, which shows the salient features of the teleomorph and can be discriminated easily from all previously described species of the H. rubiginosum complex. The stromata of the holotype specimen differ from H. texense (i.e. the closest relative in the phylogeny), in having stromata with hemispherical to pulvinate shape, Orange (7) KOH-extractable pigments and larger ascospores [12-15 × 5-6 vs. 9.1-10.8 (-11.5) × (4.0-) 4.5-5.4 (-5.7) μm with straight germ slit.

Hypoxylon guilanense can also be easily differentiated from H. rubiginosum sensu stricto and H. petriniae in the peculiar stromatal shape and it also has larger ascospores. H. cercidicola differs from H. guilanense in having erumpent stromata with discoid shape and smaller ascospores [(9-) 9.5-12 × 5-6 μm)] with straight to slightly sigmoid germ slit. Table 2 compares morphological characters of some other taxa that may be confused with H. guilanense .

Figures

Figure 2. Hypoxylon guilanense (Holotype GUM 989) A stromatal habit B close-up view of stromatal surface, with stromatal pigments in 10 % KOH C, H, I ascospores in water, with germ-slits D, E ascospores in 10 % KOH with dehiscent perispore F, G ascospore under SEM J, K culture on 9 cm OA plates after 1 and 3 wk of incubation (left to right). Scale bars: 2.5 mm (A), 1 mm (B); 10 µm (C-E); 2 µm (F, G); 10 µm (H, I).