Nigrograna camelliae Y. H. Lu, H. Z. Du & Jian K. Liu, 2024

Du, Hong-Zhi, Lu, Yu-Hang, Cheewangkoon, Ratchadawan & Liu, Jian-Kui, 2024, Morpho-phylogenetic evidence reveals novel species and new records of Nigrograna (Nigrogranaceae) associated with medicinal plants in Southwestern China, MycoKeys 110, pp. 1-33 : 1-33

Nigrograna camelliae Y. H. Lu, H. Z. Du & Jian K. Liu sp. nov.

Fig. 5

Etymology.

The epithet ‘ camelliae ’ refers to the host genus Camelliae from which the fungus was originally isolated.

Holotype.

HKAS 131310

Description.

Saprobic on dead branches of Camellia sinensis ( Theaceae ). Sexual morph: Ascomata 137–270 μm wide, 208–324 μm high (x ̅ = 212 × 265 μm, n = 20), solitary, scattered, immersed, black spots on the host substrate, globose to subglobose, sometimes obpyriform, ostiolate, hairs of ascomata 2–3 μm wide, slightly brown, septate. Ostioles 65–138 μm long, 32–60 μm wide (x ̅ = 100 × 45 μm, n = 20) mostly central, some eccentric, with a crest-like apex. Peridium 19–30 μm (x ̅ = 23 μm, n = 20) wide, composed of 2–3 layers, comprising reddish brown to dark brown pigmented cells. Hamathecium 2–3 μm (x ̅ = 2.5 μm, n = 20) wide, composed of numerous, filiform, hyaline, aseptate or separate, filamentous, smooth-walled pseudoparaphyses. Asci 70–108 × 9–11 μm (x ̅ = 80 × 10 μm, n = 30), 8 - spored, bitunicate, fissitunicate, clavate to cylindric-clavate, short stalked, some with a swollen base, apically rounded, with a small ocular chamber. Ascospores 13–16 × 4–6 μm (x ̅ = 15 × 5 μm, n = 50), overlapping uni- to bi-seriately arranged, fusoid to ellipsoid, tapering towards the blunt ends, or blunt at both ends, straight or slightly curved, 1 - septate, constricted, with obviously guttulate, hyaline to slightly brown when immature, pale brown to brown when mature, without appendages. Asexual morph: Undetermined.

Culture characteristics.

Ascospores germinated on PDA within 24 h, and germ tubes produced from basal cell. Colonies growing on PDA reached 35–36 mm in diameter after three weeks at 25 ° C in dark, white in the whole colony and slightly bright yellow in the center from above, circular, edge entire, margin well-defined; in reverse, yellowish brown in the center, slightly brown at the margin and presented an outer ring, no pigmentation on PDA.

Material examined.

China • Sichuan Province, Yaan City, Mingshan County, Mengding Mountain . 30°4'32"N, 103°2'23"E, elevation 1,200 m, on dead branches of medicinal plant Camellia sinensis (L.) O. Ktze . ( Theaceae ), 16 July 2023, Y. H. Lu & X. D. Liang, MD 03 A ( HKAS 131310 , holotype; HUEST 23.0197 , isotype); ex-holotype living culture CGMCC 3.25625 ; ex-isotype living culture UESTCC 23.0197 .

Notes.

Nigrograna camelliae is phylogenetically close to N. coffeae and represents as a distinct lineage (Fig. 1 ). Additionally, the nucleotide base pair comparison between N. camelliae (ex-type strain, CGMCC 3.25625 ) and N. coffeae (ex-type strain, ZHKUCC 22-0210) revealed 15 / 514 bp (2.9 %, 1 gap) of ITS, 11 / 698 bp (1.6 %, without gaps) of LSU, 74 / 739 bp (10.0 % without gaps) of rpb 2 and 28 / 914 bp (3.1 %, without gaps) of tef 1 - α differences. Furthermore, N. camelliae morphologically resembles N. coffeae in having immersed ascomata, clavate and short pedicellate asci, pale brown to brown and septate ascospores with obviously guttulate ( Lu et al. 2022). However, N. camelliae differs from N. coffeae in having ascomata with hairs and ostioles, solitary or scattered in the substrate. Additionally, they can be distinguished in having larger ascomata (208–324 × 137–270 µm vs. 140–200 × 90–140 µm) and asci (70–108 × 9–11 µm vs. 50–70 × 7–11 µm). Therefore, N. camelliae is introduced as a new species with the justification of phylogenetic and morphological evidence.

Figures

Figure 1. Phylogenetic tree constructed from maximum likelihood (RAxML) analyses of a combined ITS, LSU, rpb 2, SSU, and tef 1 - α sequence data for selected genera within the family Nigrogranaceae (Pleosporales, Dothideomycetes). Branches support for Maximum likelihood (MLBS) equal to or greater than 75 % and Bayesian inference posterior probabilities (BIPP) equal to or greater than 0.95 are marked above or below nodes as MLBS / BIPP. The abbreviation T indicates the ex-type strain. Species names and culture collections in red are newly collected taxa and synonymized isolates. The tree was rooted with Occultibambusa pustula (MFLUCC 11-0502) and O. bambusae (MFLUCC 13-0855).

Figure 5. Nigrograna camelliae (HKAS 131310, holotype) a host Camellia sinensis b branch of Camellia sinensis c – e appearance of ascomata on host surface f, g vertical section through ascoma h peridium i hairs on ascomata j – m, w, x asci n – s ascospores t germinated ascospore u, v colony on PDA, above (u) and below (v). Scale bars: 100 µm (f, g); 20 µm (h – m, w, x); 5 µm (n – s); 10 µm (t).