Nigrograna asexualis L. Lu & Tibpromma sp. nov.

Fig. 4

Etymology.

The species epithet ' Nigrograna asexualis ' refers to the asexual morph.

Holotype.

ZHKU 22-0123.

Description.

Saprobic on decaying branch of Coffea arabica. Sexual morph: Undetermined. Asexual morph: Coelomycetous. Pycnidia 100-230 µm high, 120-180 µm wide (x̄ = 156 × 144 µm, n = 10), globose to subglobose, or pyriform, immersed, solitary, unilocular, dark brown, papillate ostiole, appearing as black spots on host surface. Pycnidial wall 11-16 µm wide (x̄ = 14 µm, n = 15), brown (#937463), the wall with pseudoparenchymatous cells. Conidiophores arising from the pycnidial wall, up to 46 µm long and 3-4.4 µm wide (x̄ = 3.4 µm, n = 25), filiform, septate, hyaline, simple to sparsely branched, with pegs along one or two sides and solitary phialides terminally. Phialides 3-6 × 1-2 µm (x̄ = 4.5 × 1.5 µm, n = 15), variable in shape, phialidic, discrete, ampulliform-lageniform-subcylindrical. Conidia 5-6.5 × 3-4 µm (x̄ = 5.5 × 3.7 µm, n = 30), ellipsoidal, unicellular, aseptate with 1-2 granules, subhyaline, smooth-walled.

Culture characteristics.

Conidium germinated on PDA within 24 h. Colonies growing on PDA reaching 5 cm diam. after two months at room temperature (22-26 °C). Colony dense, circular, surface sparsely hairy, radially striate, with a fimbriate edge, yellowish (#eabf83) to pale brown (#e1af33) at the center and dark brown (#6e5031) at the margin, reverse dark brown (#6e5031).

Material examined.

Pu'er City, Yunnan Province, China, on a decaying branch of Coffea arabica, (22°36'2"N, 101°0'59"E, 1016.43 m), 16 September 2021, LiLu, Puer 1-14 (ZHKU 22-0123, holotype), ZHKUCC 22-0214 = ZHKUCC 22-0215. GenBank number; ITS: OP450965, LSU: OP450971, rpb 2: OP432241, SSU: OP450979, tef 1-α: OP432245 (ZHKUCC 22-0214, ex-type); ITS: OP450966, LSU: OP450972, rpb 2: OP432242, SSU: OP450980, tef 1-α: OP432246 (ZHKUCC 22-0215) .

Notes.

In multi-gene phylogeny, Nigrograna asexualis formed a separate (68% ML, 0.97 BIPP) and distinct clade within Nigrograna (Fig. 1). Morphologically, N. asexualis conforms to the morphological characteristics of Nigrograna by having hyaline or subhyaline, long and branched conidiophores, solitary phialides, and aseptate, ellipsoidal or cylindrical conidia (Jaklitsch and Voglmayr 2016; Dayarathne et al. 2020; Wanasinghe et al. 2020). Blast results of the sequences show that ITS is similar to N. fuscidula with 89% (MH856004), and SSU is similar to N. mycophila with 99.8% (KX650510). Nigrograna asexualis is different from N. fuscidula and N. mycophila by its ellipsoidal conidia, but the similarities of these three species are hyaline, 1-celled, smooth-walled conidia forming on philipides (Jaklitsch and Voglmayr 2016). The LSU and rpb 2 sequences of our strain blast results are similar to N. obliqua, and the similarities are 98.9% (KX650560) and 87% (KX650579) respectively, but N. obliqua lacks the asexual morph (Jaklitsch and Voglmayr 2016). The tef 1-α sequence of our strain is 95.8% (MF939615) similar to N. locuta-pollinis, which was isolated from hive-stored pollen of Brassica campestris L. that lacks morphology (Zhao et al. 2018). Therefore, we introduce N. asexualis as a distinct new species from coffee in China.