Nigrograna coffeae 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 coffeae L. Lu & Tibpromma sp. nov.

Fig. 2

Etymology.

Species epithet refers to the host genus " Coffea " where the fungus was isolated.

Holotype.

ZHKU 22-0121.

Description.

Saprobic on decaying branch of Coffea arabica . Sexual morph: Ascomata 90-140 µm high, 140-200 μm wide (x̄ = 115 × 168 μm, n = 10), immersed, solitary, black spots on substrate, subglobose to oval, sometimes obpyriform, some with ostiolate. Peridium 10-15 µm wide, composed of 3-5 layers, hyaline to brown (#937463) cells of textura angularis. Hamathecium 1.5-3 μm wide, composed of numerous, hyaline, filamentous, septate, branched, pseudoparaphyses. Asci 50-70 × 7-11 μm (x̄ = 58 × 9 μm, n = 20), 8-spored, bitunicate, fissitunicate, clavate to cylindric-clavate, short stalked, some with club-shape pedicel, apically rounded, with a small ocular chamber. Ascospores 12-16 × 4-5 μm, (x̄ = 14.4 × 4.6 μm, n = 30), overlapping uni- to bi-seriately arranged, fusiform, straight or slightly curved, hyaline when immature and become pale brown (#e1af33) to dark-brown (#6e5031) when mature, mostly 1-septate, few 2 or 3-septate, constricted at each septum, with obviously guttulate. Asexual morph: Undetermined.

Culture characteristics.

Ascospores germinated on PDA within 24 h and germ tubes arising from both ends. Colonies on PDA, reaching 4.5 cm diam. after two months of incubation at room temperature (22-26 °C), initially white (#f2f3f4) becoming grey (#bbbeb2) to dark brown (#6e5031) at maturity, dense, circular, slightly raised, smooth surface, radially fimbriate at the edge, reverse dark green (#3a4543) to brown (#937463).

Material examined.

Pu'wen Town , Xishuangbanna, Yunnan Province, China, on a decaying branch of Coffea arabica , (22°31'18"N, 101°2'44"E, 856.89 m), 15 September 2021, LiLu, JHPW16 (ZHKU 22-0121, holotype), ZHKUCC 22-0210 = ZHKUCC 22-0211. GenBank number; ITS: OP450967 , LSU: OP450973 , rpb 2: OP432243 , SSU: OP450981 , tef 1-α: OP432247 (ZHKUCC 22-0210, ex-type); ITS: OP450968 , LSU: OP450974 , rpb 2: OP432244 , SSU: OP450982 , tef 1-α: OP432248 (ZHKUCC 22-0211) .

Notes.

Our phylogenetic analyses showed that Nigrograna coffeae forms an independent clade (100% ML, 1.00 BIPP, Fig. 1 ), and is phylogenetically related to N. yasuniana and N. jinghongensis . Nigrograna yasuniana was reported as endophytes from Conceveiba guianensis Aubl. in Ecuador, but there were not enough morphological data, the comparison of base pairs in ITS showed 3.4% differences (15/433 bp), LSU showed 1.5% differences (12/812bp), SSU only showed 0.3% differences (3/1028 bp), rpb 2 showed 14% differences (117/829 bp), and tef 1-α showed 3.2% differences (31/954 bp) ( Kolařík et al. 2017). Nigrograna jinghongensis was introduced as a saprobic fungus from woody litter in China, and our new isolate shares a similar size (12-16 × 4-5 μm vs 12-15 × 4-5.5 µm) and color (hyaline to dark brown vs yellowish-brown to brown) of ascospores with N. jinghongensis ( Boonmee et al. 2021), but there are some significant differences in the size of the ascomata (90-140 µm high, 140-200 μm wide vs 300-400 µm high 220-300 μm wide) and the shape of ascospores (fusiform, straight or slightly curved vs ellipsoid) ( Boonmee et al. 2021). Based on the sequence blast results, ITS, LSU and rpb 2 gene sequences were similar to Nigrograna sp., with 97.5% (MZ270683), 98.4% (MK762716), and 86% (MZ508421) respectively, SSU was similar to N. mycophila with 99% (KX650510), and tef 1-α was similar to N. yasuniana with 96.6% (LN626670). Therefore, we introduce our new isolate as a new species N. coffeae based on both morphological characteristics and phylogenetic analyses.

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 2. Nigrograna coffeae (ZHKU 22 - 0121, holotype) a, b ascomata on the host substrate c a vertical section through an ascoma d peridium e hamathecium f-k asci l germinated ascospore m culture on pda from above and reverse n-s ascospores (arrows indicate the septa). Scale bars: 50 μm (c); 10 μm (d-l); 5 μm (n-s).