Xylaria hedyosmicola Hai X. Ma & X.Y. Pan, 2022

Pan, Xiao-Yan, Song, Zi-Kun, Qu, Zhi, Liu, Tie-Dong & Ma, Hai-Xia, 2022, Three new Xylaria species (Xylariaceae, Xylariales) on fallen leaves from Hainan Tropical Rainforest National Park, MycoKeys 86, pp. 47-63 : 47

Xylaria hedyosmicola Hai X. Ma & X.Y. Pan sp. nov.

Figure 2

Diagnosis.

Differs from X. vagans by its stromata without a black rhizomorphoid mycelium connecting dead leaves, larger ascospores and tubular to slightly urn-shaped apical apparatus. Differs from X. betulicola by its smaller stromta and larger ascospores.

Typification.

China. Hainan Province, Lingshui County, Diaoluoshan Natural Reserve, on fallen leaves of Hedyosmum orientale ( Chloranthaceae ), 31 December 2020, Haixia Ma (holotype, FCATAS 856).

Etymology.

" Xylaria hedyosmicola " refers to the growth on leaves of Hedyosmum orientale .

Teleomorph.

Stromata upright, solitary to cespitose, thread-like, unbranched or occasionally branched once at top, 2-5.5 cm total length; with a long sterile filiform apex up to 0.5-3 cm long; fertile part 3-17 mm long × 0.5-1 mm diam., usually consisting of closely packed or scattered perithecia; stipe 8-18 mm long × 0.1-0.5 mm diam., glabrous, finely longitudinally striate, the base slightly swollen; surface roughened, with half-exposed to fully exposed perithecial contours and wrinkles. Externally black, interior white. Texture soft. Perithecia subglobose, 200-470 µm diam. Ostioles papillate, 11-22 µm diam. Asci with eight ascospores arranged in uniseriate manner, cylindrical, 105-160 µm total length, the spore-bearing parts 70-100 µm long × 8-12 µm broad, the stipes 25-70 µm long, with apical apparatus bluing in Melzer’s reagent, tubular to slightly urn-shaped, 2.5-4.8 µm high × 2.5-3.5 µm broad. Ascospores brown, unicellular, ellipsoid-inequilateral, with narrowly rounded ends, smooth, (12-)13-15(-16.7) × (6-) 6.5-7.5 (-8.5) µm (M = 14 × 7 µm, n = 60), straight to slightly sigmoid germ slit spore-length or almost spore-length, with a slimy sheath on ventral side swollen at both ends to form rounded non-cellular appendages visible in Indian ink.

Additional specimen examined.

China. Hainan Province, Lingshui County, Diaoluoshan Natural Reserve, on fallen leaves of Hedyosmum orientale , 31 December 2020, Haixia Ma (FCATAS 857).

Remarks.

Xylaria hedyosmicola closely resembles X. vagans Petch by sharing thread-like or long hair-like stromata bearing closely packed or scattered perithecia with a long sterile filiform apex. Xylaria vagans was originally described and illustrated by Petch (1915) from Sri Lanka. However, based on comparisons of the descriptions and illustrations, there were some differences between the two species. Xylaria hedyosmicola has larger sporiferous part of asci (70-100 µm × 8-12 µm) with tubular to slightly urn-shaped apical apparatus bluing in Melzer’s reagent, brown and larger ascospores with straight (Fig. 2n and p ) to slightly sigmoid germ slit (Fig. 2o ), with narrowly rounded ends and a slimy sheath on ventral side swollen at both ends to form rounded non-cellular appendages, while X. vagans has a black rhizomorphoid mycelium connecting dead leaves, smaller sporiferous part 68-72 µm × 6 µm and black-brown, cymbiform, smaller ascospores 9-12 × 5-6 µm, with broadly rounded ends and is without apical apparatus, germ slit and sheath or appendages ( Petch 1915). Unfortunately, the molecular sequences of X. vagans from Sri Lanka were not available.

Xylaria betulicola Hai X. Ma, Lar.N. Vassiljeva & Yu Li is similar to X. hedyosmicola in stromatal morphology, but differs in having larger stromata 3-7 cm, slightly smaller ascospores (11.5)12-14(15) × 5-6 µm, without sheath or appendages ( Ma and Li 2018). In the phylogenetic tree, X. hedyosmicola formed a fully supported clade with Xylaria sp. 6 from Hawaiian Islands, USA ( Hsieh et al. 2010). Although there are no descriptions on Xylaria sp. 6 in the study of Hsieh et al. (2010), we suspected that it is conspecific with X. hedyosmicola . The sequences comparison showed that there are 98.7%, 99% and 99.9% maximal percentage identities, respectively in ITS, TUB and RPB2 between X. hedyosmicola (FCATAS 856) and Xylaria sp. 6 from USA (JDR 258).

Figures

Figure 2. Xylaria hedyosmicola (FCATAS 856, holotype) a, b, e stromata on leaves (b, FCATAS 857) c stromatal surface d section through stroma, showing a perithecium f immature asci in water g, h ascal apical ring in Melzer's reagent i, j ascospores in Melzer's reagent k ascus in 1 % SDS l, m asci and ascal apical ring in Melzer's reagent n ascospore in Melzer's reagent showing straight germ slit o ascospore in Melzer's reagent showing slightly sigmoid germ slit p, q ascospore showing a slimy sheath and non-cellular appendages in India ink. Scale bars: 1 cm (a, b); 0.1 mm (c, d); 0.5 mm (e); 20 µm (f, m); 10 µm (g-l, n-q).