Neopestalotiopsis theobromicola Fallahi, Jayawar. & K. D. Hyde, 2025

Fallahi, Maryam, Armand, Alireza, Al-Otibi, Fatimah, Hyde, Kevin D. & Jayawardena, Ruvishika S., 2025, Pathogenic fungi (Sordariomycetes) associated with annual and perennial crops in Northern Thailand, MycoKeys 117, pp. 191-265 : 191-265

Neopestalotiopsis theobromicola Fallahi, Jayawar. & K. D. Hyde sp. nov.

Fig. 31

Etymology.

‘ theobromicola ’ refers to the host plant genus from which the fungus was isolated.

Description.

Associated with leaf spots of cacao ( Theobroma cacao ). Sexual morph not observed. Conidiomata acervularon on PDA, aggregated and scattered, immersed and semi-immersed in agar medium, exuding black conidial mass. Conidiophores reduced to conidiogenous cells. Conidiogenous cells hyaline to pale brown, subcylindrical to ampuliform, 3–7 × 2–5 μm. Conidia clavate or fusiform, straight or slightly curved, yellow-brown to brown, 4 septate, 20–30 × 5–7.5 μm (mean = 26 × 6.5 μm, n = 30). Basal cell hyaline, conoid, with truncate base, 3.5–8 μm long; median cells, versicolored, darker than other cells, 14–19 μm long (mean = 17 μm, n = 30) (second cell from the base yellow-brown, 4–6.8 μm long; third cell from the base medium brown, 4.6–7 μm long; fourth cell from the base pale to medium brown, 4–7 μm long); apical cell hyaline, conic, 3–6 μm with 2–3 tubular apical appendages, hyaline, filiform, unbranched, and 15–29 μm long (mean = 22.5 μm, n = 30); basal appendage tubular, unbranched, solitary, hyaline, and 2–5.5 μm long.

Culture characteristics.

Colonies on PDA reach 65–70 mm in diameter after seven days of growth at 25 ° C under 12 h daylight, white with moderate aerial mycelium, shape irregular, edge undulated, margin fluffy, with black conidial mass. The upper view is white, reverse honey-colored with age.

Material examined.

Thailand • Chiang Rai Province, Phan District, Sai Khao , on leaf spots in cacao ( Theobroma cacao ), February 2023, Maryam Fallahi, dried culture MF 115-1 ( MFLU 24-0258 , holotype), ex-holotype culture MFLUCC 24-0253 .

Notes.

Strain MFLUCC 24-0253 formed an independent branch in the subclade, including the strains and ex-type strains of Neopestalotiopsis acrostichi and N. guajavicola with 75 % ML bootstrap support and 0.94 BYPP (Fig. 28 ), and is introduced here as a new species, namely Neopestalotiopsis theobromicola . The base pair differences between N. theobromicola strains MFLUCC 24-0253 (holotype) and MFLUCC 17-1754 (ex-type) revealed a 0.40 % nucleotide difference in ITS (2 / 504 bp, 3 gaps) and no difference in tef 1 and tub 2. The base pair differences between N. theobromicola (ex-type strain MFLUCC 24-0253 ) and ex-type strains of N. guajavicola (FMBO 129) revealed a 0.20 % nucleotide difference in ITS (1 / 506 bp), 0.26 % differences in tef 1 (1 / 426 bp), and 0.25 % differences in tub 2 (1 / 396 bp). Neopestalotiopsis theobromicola (ex-type strain MFLUCC 24-0253 ) differs from the type strain of N. acrostichi by having the conidia with 2-3 apical appendages ( N. acrostichi : conidia with 3-5 apical tubular appendages, (16 –) 19–28. 5 (– 33. 5) μm long) ( Norphanphoun et al. 2019). Neopestalotiopsis theobromicola ( MFLUCC 24-0253 ) differs from the type strain of N. guajavicola by having larger conidia with an L / W ratio = 4 (26 × 6.5 μm in N. theobromicola (ex-type strain MFLUCC 24-0253 ) vs. 23.3 ± 1.6 × 6.5 ± 0.5 μm in N. guajavicola (FMBO 129 )) ( UI Haq et al. 2021).

Figures

Figure 28. Phylogenetic tree of the Neopestalotiopsis ssp. generated by Bayes analysis of combined ITS, tef 1, and tub 2 sequence data. The ultrafast maximum likelihood (ML) bootstrap support values ≥ 50 % (BT) and Bayesian posterior probabilities ≥ 0.95 (BYPP) are shown, respectively, near the nodes. The ex-type strains are marked with an asterisk. The tree is rooted in Pestalotiopsis spathulate (CBS 356 86) and Pestalotiopsis diversiseta (MFLUCC 12 0287).

Figure 31. Neopestalotiopsis theobromicola (MFLUCC 24-0253, holotype) a leaf spots in cacao b front, and c back views of the colony on PDA after 30 days at 25 ° C d conidiomata on SNA e – i conidiophore and conidiogenous cells j – n conidia. Scale bars: 20 μm.