Diaporthe melonis Beraha & M. J. O’Brien

Diaporthe melonis Beraha & M. J. O’Brien View in CoL , Phytopath. Z. 94 (3): 205 (1979)

Fig. 2 View Figure 2

Description.

Saprobic on dead unidentified branch. Sexual morph: not observed. Asexual morph: Conidiomata 148–374 × 128–338 µm high (x ̄ = 250 × 225 µm, n = 15), pycnidial, mostly scattered, immersed, slightly erumpent through the host surface, discoid or subglobose, with a solitary undivided locule. Conidiophores reduced to conidiogenous cells. Alpha conidiogenous cells 5.7–25 × 1.1–2.5 µm (x ̄ = 15.6 × 1.7 µm, n = 50), hyaline, rarely branched, mostly aseptate, densely aggregated, cylindrical, straight to slightly curved and smooth. Alpha conidia 5–7.3 × 1.9–2.7 µm (x ̄ = 6.3 × 2.3 µm, n = 40), unicellular, fusiform to ellipsoidal, apex and base rounded, hyaline, smooth, bi-guttulate. Beta conidiogenous cells 6.2–16 × 1.6–2.6 µm (x ̄ = 9.4 × 2.1 µm, n = 40), phialidic, subcylindrical, tapering towards the apex, hyaline. Beta conidia 19–27 × 1–2 µm (x ̄ = 23 × 1.5 µm, n = 40), filiform, aseptate, hyaline, smooth-walled, straight from base, and curve at apex. Gamma conidia not observed.

Culture characteristics.

Colonies on PDA, reaching 20 mm diam., after 3 weeks at 25 ° C, initially white, turning beige after 7–10 days, flat, felty with a thick texture at the centre and marginal area, lacking aerial mycelium; reverse, glossy grey, radiating outwardly.

Material examined.

Thailand, Chiang Rai Province, Muang District , on a dead unidentified dicot branch, 16 January 2023, J. Louangphan, CR 1-02 ( MFLU 23–0474 ); living culture MFLUCC 24–0522 = MFLUCC 23–0300 .

Hosts.

Annona squamosa ( Annonaceae ), Berberis aristata ( Berberidaceae ), Carapa guianensis ( Meliaceae ), Citrus grandis cv. Tomentosa ( Rutaceae ), Cucumis melo ( Cucurbitaceae ), Glottidium sp. ( Fabaceae ), Glycine max , G. soja ( Fabaceae ), unidentified branch ( Dong et al. 2021 a, b; Hongsanan et al. 2023; This study).

Distribution.

China, Myanmar, India, Indonesia, Japan, Thailand, the United States ( Dong et al. 2021 a, b; Hongsanan et al. 2023; this study).

Notes.

Our isolates ( MFLUCC 23–0300 and MFLUCC 24–0522 ) clustered with D. melonis isolates ( CBS 507.78, FAU 640, and ZHKUCC 20-0014 ) with 100 % ML / 1.00 BPP support (Fig. 1 View Figure 1 ). Our isolate has a similar morphology to D. melonis but differs in having smaller conidiomata (148–374 µm vs. 100–500 µm diam.) and smaller alpha conidia (6.3 × 2.3 µm vs. 8.3 × 2.6 µm) ( Beraha and O’Brien 1979). Our isolate has a beige culture compared to the brown culture of D. melonis ( Beraha and O’Brien 1979) . Our isolate also differs from D. melonis ( D. guangdongensis ZHKUCC 20-0014 ) in the size of conidiomata (128–338 × 148–374 µm vs. 130–515 × 100–390 µm), alpha conidia (5–7.3 × 1.9–2.7 µm vs. 6–8 × 2–4 µm), and beta conidia (19–27 × 1–2 µm vs. 14–35 × 1–2 µm) ( Dong et al. 2021 a, b). Therefore, we report our isolate as a new geographical record of D. melonis from Thailand.