Nigrograna asexualis L. Lu & Tibpromma, 2022

Lu, Li, Karunarathna, Samantha C., Dai, Dong-qin, Jayawardena, Ruvishika S., Suwannarach, Nakarin & Tibpromma, Saowaluck, 2022, Three new species of Nigrograna (Dothideomycetes, Pleosporales) associated with Arabica coffee from Yunnan Province, China, MycoKeys 94, pp. 51-71 : 51

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.

Figures

Figure 1. The maximum-likelihood phylogram of Nigrograna based on a combined SSU, LSU, ITS, rpb 2 and tef 1 - α sequence dataset with Cyclothyriella rubronotata CBS 141486 and CBS 419.85 as the outgroup taxa (Dayarathne et al. 2020). The maximum-likelihood bootstrap values (ML ≥ 60 %, left) and Bayesian Inference Posterior Probability values (BIPP ≥ 0.90, right) are shown above the nodes. Strains derived from the current study are in blue, while type strains are in bold.

Figure 4. Nigrograna asexualis (ZHKU 22 - 0123, holotype) a, b conidiomata on the host substrate c, d vertical sections of a conidioma e peridium f, g conidiophores with phialides h conidia i culture on PDA from above and reverse. Scale bars: 100 μm (c); 50 μm (d); 15 μm (e); 30 μm (f); 20 μm (g); 10 μm (h).