Nigrograna trachycarpus H. M. Hu & Q. R. Li, 2023

Hu, Hongmin, He, Minghui, Wu, Youpeng, Long, Sihan, Zhang, Xu, Liu, Lili, Shen, Xiangchun, Wijayawardene, Nalin N., Meng, Zebin, Long, Qingde, Kang, Jichuan & Li, Qirui, 2023, Taxonomic and phylogenetic characterisations of six species of Pleosporales (in Didymosphaeriaceae, Roussoellaceae and Nigrogranaceae) from China, MycoKeys 100, pp. 123-151 : 123

Nigrograna trachycarpus H. M. Hu & Q. R. Li sp. nov.

Fig. 9

Type material.

Holotype: GMB0499.

Etymology.

Named after the host genus Trachycarpus from which the fungus was isolated.

Description.

Saprobic or parasitic on dead culms of Trachycarpus sp.

Sexual morph: Ascomata 160-380 μm wide, 100-210 μm high, pyriform to globose, scattered or clustered in small groups, black, immersed, the base remaining immersed in the substrate, smooth, with ostiole. Ostiole single, central, flattened, with a short neck, without paraphyses. Peridium 22-34 μm wide, multi-layered, composed of 4-6 rows of heavily pigmented, light brown to dark brown cells of textura angularis. Hamathecium comprising numerous 1.4-2.2 μm diameter, filamentous, unbranched, anastomosing, septate pseudoparaphyses. Asci 86-126 × 11-13 μm (average = 99 × 12 μm, n = 25), 8-spored, bitunicate, with fissitunicate dehiscence occurring rarely, elliptical, shortly pedicellate, apically rounded, with an ocular chamber, with a J-subapical ring. Ascospores 15-17 × 5-7 μm (average = 16.3 × 6.1 μm, n = 40), hyaline to yellow brown, 2-3-septate, deeply constricted at second septum, tapering to each end, the widest point at second cell from apex, smooth-walled, distinctly guttulate, without a sheath or appendages. Asexual morph: undetermined.

Culture characteristics.

After 4 weeks at 25 °C on PDA, colonies typically reach 2-2.5 cm in diameter. They present a circular shape with a dense and elevated centre, while appearing sparse and radiating at the margin. The colonies exhibit colours ranging from dark grey to pale olivaceous when viewed from above and from dark olivaceous to black on reverse.

Specimen examined.

China, Guizhou Province, Guiyang Huaxi National Urban Wetland Park (26°2'2.34"N, 106°34'16.22"E), 1130 m elev., on decaying culms of Trachycarpus sp., 12 October 2022, Y.P Wu and H.M Hu, 2022 HXGY11 (GMB0499, holotype, GMBC0499, ex-type; KUN-HKAS 12984, isotype).

Other examined material.

China, Guizhou Province, Qiannan Prefecture, Sandu Shui Autonomous County, Yao Man Mountain National Forest Park (25°93′18.76"N, 107°95′15.66"E), 540 m elev., on decaying bamboo culms of Trachycarpus sp.; 28 September 2022; Y.P. Wu, 2022YRS50 (GMB050; GMBC0505, living culture) .

Notes.

In the phylogenetic analysis, Nigrograna trachycarpus and N. locuta-pollinis F. Liu & L. Cai formed a monophyletic branch within the Nigrograna genus, with a bootstrap support value of 31% (Fig. 3 ). However, this relationship remained consistent in repeated phylogenetic analyses. Sequences generated from the cultures of N. trachycarpus are similar to sharing an ITS similarity of 70.7% (with 57/488 gaps) and a tef1 similarity of 89.8% (with 0/481 gaps). Morphologically, N. trachycarpus can be distinguished by its larger ascospores, measuring 16.3 × 6.1 μm, in contrast to N. schinifolium 's ascospores, 11.6 × 3.3 μm. Morphologically, it is close to N. impatientis J.F. Zhang, J.K. Liu & Z.Y. Liu, but the latter typically has ascocarps in groups of 2-6 with ostiole necks penetrating the host surface together. Moreover, the N. trachycarpus a possesses longer asci (measuring 99 × 12 μm) and larger ascospores (measuring 16.3 × 6.1 μm) compared to N. impatientis (asci measuring 48 × 8, ascospores measuring 12 × 4.3 μm) ( Zhang et al. 2020a).

Figures

Figure 3. RAxML phylogram of Nigrogranaceae, based on a combined dataset of ITS and tef 1 DNA sequences. The tree is rooted by Occultibambusa pustula (MFLUCC 11 - 0502) and O. bambusae (MFLUCC 13 - 0855). Bootstrap supports ML (MLB ≥ 75 %) and Bayesian posterior probabilities (BYPP ≥ 0.95) are given as MLB / BYPP above the branches. Sequences from newly-generated isolates are in red, bold letters, while those of ex-type isolates are shown in black, bold letters.

Figure 9. Nigrograna trachycarpus (GMB 0499) A specimen B, C appearance of ascomata on substrate D, E longitudinal section of an ascoma F peridium G-I asci J pseudoparaphyses K J-ascus subapical ring in Melzer's L-O ascospores. Scale bars: 0.5 mm (B-D); 10 μm (E-O).