Diaporthe hongkongensis R. R. Gomes, Glienke & Crous

Diaporthe hongkongensis R. R. Gomes, Glienke & Crous, Persoonia 31: 23 (2013) Fig. 15 Description. Pathogenic to rambutan (Nephelium lappaceum) and causes fruit rot. Sexual morph not observed. Conidiomata pycnidial, superficial to embedded, solitary to aggregated, pyriform or globose with central ostiole, and cream conidial mass, up to 250 μm in diameter. Conidiophores, hyaline, smooth, septate, subcylindrical. Paraphyses intermingled among conidiophores, hyaline, smooth, branched, septate, with clavate terminal cell, 30–50 × 0.5–1.3 μm (38 × 1 μm, n = 20). Alpha conidia aseptate, hyaline, smooth, ovate to ellipsoidal, granular to guttate, 5.7–7.8 × 1.5–2.5 μm (6.5 × 2 μm, n = 30). Beta conidia filiform, curved at one tip, hyaline, aseptate, rounded at tips, 15–25 × 1–2 μm (20 × 1.5 μm, n = 30). Gamma conidia absent. Culture characteristics. Colonies on PDA reach 70–80 mm in diameter after seven days of growth at 25 ° C in the dark, felted, fluffy margin, pale olivaceous-grey, with an obvious pale brown concentric ring of dense hyphae, and turn into pale brown with age. Material examined. Thailand • Chiang Rai Province, Mueang Chiang Rai District, Ban Du, lesion of rambutan (Nephelium lappaceum) fruit, June 2023, Maryam Fallahi, dried culture L 2-3 (MFLU 24-0247), living culture, MFLUCC 24-0246. Notes. Based on phylogenetic analysis, strain MFLUCC 24-0246 grouped in the Diaporthe arecae species complex with Diaporthe hongkongensis (CBS 115448, ex-type) with 72 % ML bootstrap support and 0.78 BYPP (Fig. 12). The base pair differences between D. hongkongensis strains MFLUCC 24-0246 and CBS 115448 revealed a 0.75 % (4 / 533 bp) difference in ITS, a 0.66 % (2 / 301 bp) difference in tef 1, a 3.84 % (16 / 416 bp) difference in tub 2, and a 0.46 % (2 / 433 bp) difference in cal, and no difference in his 3. Diaporthe hongkongensis (MFLUCC 24-0246) and the ex-type strain of D. hongkongensis (CBS 115448) are similar. Adding more strains of D. hongkongensis in phylogenetic analyses in this study revealed that strains of this species were dispersed throughout the subclade. The relationships among these species remain uncertain, necessitating further analysis to resolve the confusion surrounding their classification and clarify their taxonomic relationships. Recently, a combined gene phylogeny analysis by Dissanayake et al. (2024) redefined the species boundaries of D. hongkongensis. The study proposed that eight previously distinct species, D. australiana, D. eucalyptorum, D. eucommiae, D. lagerstroemiae, D. lithocarpus, D. rhodomyrti, and D. salinicola, are a single species, D. hongkongensis (Dissanayake et al. 2024). Diaporthe hongkongensis was first isolated from the fruit of Dichroa febrifuga in Hong Kong, China (Gomes et al. 2013), which usually causes trunk diseases. It was reported as a cause of top blight of Cunninghamia lanceolata (Liao et al. 2023), fruit rot in Prunus persica (Zhang et al. 2021), and shoot canker in Pyrus communis (Guo et al. 2020). This study provides a new host and geographical record for D. hongkongensis on rambutan in northern Thailand.