Nigropunctata chiangraiensis Z. L. Tun & K. D. Hyde, 2024

Tun, Zaw Lin, Gomdola, Deecksha, Maharachchikumbura, Chitrabhanu S. Bhunjun Sajeewa S. N., Alotibi, Fatimah & Hyde, Kevin D., 2024, A novel species and a new geographical record of Nigropunctata from Bambusa vulgaris in northern Thailand, Phytotaxa 676 (2), pp. 155-168 : 160-162

Nigropunctata chiangraiensis Z. L. Tun & K. D. Hyde , sp. nov. ( Fig. 2 )

Index Fungorum number: IF 901628, Facesoffungi number: FoF 16955

Etymology:—The specific epithet refers to Chiang Rai province, where the specimen was collected.

Holotype:— MFLU 23-0383

Saprobic on dead branches of Bambusa vulgaris . Sexual morph: Ascomata 400–480 × 300–380 μm (x̄ = 459 × 345 μm, n = 5) immersed, unilocular, solitary or gregarious, perithecial, globose to subglobose, ostiolate. Ostioles 75–100 × 70–76 μm wide (x̄ = 92.6 × 75.2 μm, n = 5), central, covered with black, thick-walled clypeus. Ectostroma yellow. Peridium 200–240 μm wide (x̄ = 216 μm, n = 5), comprising two cell layers, outer layer composed of dark brown, thick-walled cells of textura angularis, inner layer composed of hyaline, thin-walled cells of textura angularis. Paraphyses 2–3.5 μm (x̄ = 2.9 μm, n = 10) wide, longer than asci, filamentous, sinuous, septate, constricted at septa, guttulate, embedded in a gelatinous matrix. Asci 80–160 × 9–15 μm (x̄ = 114 × 9.6 μm, n=20), unitunicate, 8-spored, cylindrical to clavate, short pedicellate, sometimes narrower at the apex, with a J +, apical ring. Apical ring 4.5–7 μm (x̄ = 5.5 μm, n = 10), discoid. Ascospores 13.5–19 × 5–7 μm (x̄ = 14.7 × 6.2, n = 20), uni-seriate, initially hyaline, turning brown upon maturation, smooth and thick-walled, cylindrical to broadly ellipsoidal, aseptate, guttulate, the ascospores covered with a thick mucilaginous sheath. Sheath 3–5 μm thick (x̄ = 3.5 μm, n = 10). germ slit on ventral side of the ascospore, straight, along the entire spore length. Asexual morph: Not observed.

Culture characteristics:—Colonies on MEA reaching 3 cm diam. after 2 weeks, incubated at 25 ° C; colonies from above white, flat, with circular margin, slightly cottony; colony from reverse yellowish.

Material examined:— Thailand, Chiang Rai Province, Mae Fah Luang University, on fallen dead branches of Bambusa vulgaris ( Poaceae ), 15 September 2022, Z. L. Tun, ZL139 ( MFLU 23-0383, holotype); ex-type living culture ( MFLUCC 23-0238).

Distribution: — Thailand.

GenBank accession numbers: —ITS = OR909712, β-tub = PQ397547, rpb2 = OR757300 and tef-1α = PQ505632.

Notes: —Our isolate, MFLUCC 23-0238, is sister to N. khalidii isolates with 87% ML and 1.00 PP statistical support. We compared the morphologies and genetic distances of MFLUCC 23-0238 with the isolates of N. khalidii . MFLUCC 23-0238 has smaller ascomata and shorter asci than N. khalidii (GMB1156) , and smaller ascospores than N. khalidii (MFLUCC 23-0237). The ascomata of MFLUCC 23-0238 are 400–480 × 300–380 μm while those of N. khalidii (GMB1156) are 608–782 × 762–830 μm, and N. khalidii (MFLUCC 23-0237) are 500–560 × 590–610 μm. The asci length of MFLUCC 23-0238 starts from 80 μm (x̄ = 114 μm, n=20) while those of N. khalidii (GMB1156) range between 146–173 μm. In addition, the ascospore lengths of MFLUCC 23-0238 measure up to 19 μm while those of N. khalidii (MFLUCC 23-0237) are up to 25 μm.

The colonies of MFLUCC 23-0238 and N. khalidii (MFLUCC 23-0237) are whitish on top and yellowish below. However, the colony of MFLUCC 23-0238 is circular in a concentric pattern while that of N. khalidii (MFLUCC 23- 0237) has an irregular margin ( Figs. 2q, 2r , 3p, 3q ).

With respect to the inter-species genetic distances between MFLUCC 23-0238 and the type of N. khalidii (GMB1156) , differences of 5.3% and 10.8% were observed across ITS (412 bp) and β-tub (397 bp) sequences, respectively. We were unable to compare the base pair differences across LSU, rpb2 and tef-1α sequences between MFLUCC 23-0238 and N. khalidii (GMB1156) , as MFLUCC 23-0238 lacks sequence data for LSU, and N. khalidii (GMB1156) lacks sequence data for rpb2 and tef-1α. However, a comparison of the genetic distances between MFLUCC 23-0238 and our strain of N. khalidii (MFLUCC 23-0237) revealed the following differences: 6.5% in ITS (520 bp), 11.4% in β-tub (421 bp), 8.6% in rpb2 (758 bp) and 3.1% in tef-1α (841 bp) sequences. The nucleotide comparison between MFLUCC 23-0238 and N. thailandica (MFLU 19-2118) showed differences of 7.7% and 2.6% across ITS (543 bp) and tef-1α (841 bp) sequences, respectively. We were unable to compare the differences across LSU and β-tub regions between MFLUCC 23-0238 and N. thailandica (MFLU 19-2118) as MFLUCC 23-0238 lacks sequence data for LSU, and N. thailandica lacks sequence data for β-tub.

Based on the variations in morphology, genetic distances between sister taxa, and the phylogenetic species recognition criteria proposed by Chethana et al. (2021), Jayawardena et al. (2021) and Maharachchikumbura et al. (2021), we establish MFLUCC 23-0238 as a new species, Nigropunctata chiangraiensis .

Figures

FIGURE 2. Nigropunctata chiangraiensis (MFLU 23-0383, holotype) a Substrate. b Appearance of ascomata on the host surface. c Section through an ascoma. d, e Vertical sections through ascomata. f Peridium. g Paraphyses. h–j Immature and mature asci. k J+ Apical ring turning blue in Melzer’s reagent. l–n Immature and mature ascospores surrounded by a mucilaginous sheath. o Ascospore with a germ slit. p Germinated ascospore. q, r Front and reverse colony on MEA. Scale bars: b, c = 200 μm, d, e = 50 μm, f, g = 5 μm, h–j = 20 μm, k = 5 μm, l–p = 50 μm.

FIGURE 3. Nigropunctata khalidii (MFLU 23-0382) a Substrate. b Appearance of ascomata on the host surface. c, d Vertical sections through ascomata. e Peridium. f Paraphyses. g J+ Apical ring turning blue in Melzer’s reagent. h, i Immature and mature asci. j–m Immature and mature ascospores. n Ascospore with a germ slit. o Germinated ascospore. p, q Front and reverse colony on MEA. Scale bars: b, c = 200 μm, d, e = 50 μm, f, g = 5 μm, h, i = 20 μm, j–o = 10 μm.