Nigrograna guttulata Y. H. Lu, H. Z. Du & Jian K. Liu 2024, sp. nov.

Nigrograna guttulata Y. H. Lu, H. Z. Du & Jian K. Liu sp. nov. Fig. 9 Etymology. The epithet ‘ guttulata ’ refers to the guttulate ascospores. Holotype. HKAS 131992. Description. Saprobic on dead branches of Camellia sinensis (Theaceae). Sexual morph: Ascomata 182–283 μm wide, 106–276 μm high (x ̅ = 241 × 183 μm, n = 20), solitary, immersed, ostiolar necks visible on the host surface or erumpent, triangular, globose to subglobose, sometimes obpyriform, coriaceous, ostiolate, dark brown to black. Ostioles 35–61 μm long, 15–30 μm wide (x ̅ = 47 × 22 μm, n = 20) mostly central, some eccentric, filled with hyaline periphyses. Peridium 15–37 μm (x ̅ = 25 μm, n = 20) wide, multi-layered, reticulate structure, comprising dark brown to reddish brown pigmented cells of textura angularis. Hamathecium 1–2.5 μm wide (x ̅ = 2 μm, n = 20), composed of numerous, filiform, hyaline, aseptate or separate, some branched, filamentous, smooth-walled pseudoparaphyses. Asci 35–70 × 7–12 μm (x ̅ = 48 × 8.5 μm, n = 30), 8 - spored, bitunicate, fissitunicate, clavate to cylindric-clavate, short stalked, some with club-shape pedicel, apically rounded, with small ocular chamber. Ascospores 10–13 × 3–5 μm (x ̅ = 12 × 4 μm, n = 50), 1–2 - seriate, overlapping, fusoid to ellipsoid, tapering towards the blunt ends, or blunt at both ends, straight or slightly curved, guttulate, smooth-walled, subhyaline to slightly brown when young, 1 - septate; yellowish-brown to dark brown when mature, becoming 3 - septate, deeply constricted at septa, 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 35–38 mm in diameter after one month at 25 ° C in dark. Colonies from above, white in the whole colony and raised in the central point, circular, margin well-defined, aerial mycelia dense; in reverse, grayish green in the center, white ring at the margin, no pigmentation on PDA. Material examined. China • Guizhou Province, Guiyang City, Huaxi District, 26°30'40"N, 106°39'30"E, elevation 1,155 m, on dead branches of medicinal plant Camellia sinensis (Linnaeus) Kuntze (Theaceae), 2 February 2023, Y. X. Yu & Y. H. Lu, GY 15 (HKAS 131992, holotype; HUEST 23.0295, isotype), ex-holotype living culture CGMCC 3.25689; ex-isotype living culture UESTCC 23.0295. Notes. Nigrograna peruviensis was reported by Kolařík et al. (2017) as an endophytic fungus (Biatriospora peruviensis) and was synonymized under the genus Nigrograna by Kolařík (2018), but with a lack of detailed morphological structures. In this study, our isolates of N. guttulata (CGMCC 3.25689 and UESTCC 23.0295) have a close phylogenetic relationship with N. peruviensis (Kolařík et al. 2017; Kolařík 2018) based on ITS, LSU, rpb 2, SSU, and tef 1 - α sequence data, and formed a distinct lineage with absolute bootstrap support (100 % MLBS / 1.00 BIPP) (Fig. 1). Additionally, N. guttulata (ex-type strain, CGMCC 3.25689) can be distinguished from N. peruviensis (ex-type strain, CCF 4485) by 8 / 462 bp (1.7 %, 3 gaps) in ITS, 24 / 1020 bp (2.4 %, without gaps) in LSU and 10 / 618 bp (1.6 %, without gaps) in rpb 2 differences. Therefore, the establishment of the new species N. guttulata is justified by the phylogenetic evidence.