Distinguished from the other Diaporthe species based on DNA sequence data and characterised by conidiomata with single necks erumpent through the host bark.

Figure 2. 

Diaporthe celticola (BJFC-S1616) a, b habit of conidiomata on twig c transverse section through conidiomata d, e conidiogenous cells with alpha conidia f alpha conidia g, h conidiomata formed on PDA. Scale bars: 200 μm (b, c); 10 μm (d–f).

Named after the host genus on which it was collected, Celtis.

Conidiomata pycnidial, 535–605 × 210–225 μm diam, solitary and with single necks erumpent through host bark. Ectostromatic disc brown, one ostiole per disc, with yellowish cream conidial drops exuding from the ostioles. Tissue around the neck is cylindrical. Locule circular, undivided, 350–375 μm diam. Conidiophores reduced to conidiogenous cells. Conidiogenous cells unbranched, straight or sinuous, apical or base sometimes swelling, (8–)10.5–13(–14.5) × 1–1.5 μm (n = 30), L/W = 8.5–10.5. Alpha conidia hyaline, aseptate, ellipsoidal, biguttulate, (5–)6–7 × 3.5–4 μm (n = 30), L/W = 1.5–1.8. Beta conidia not observed.

Colony originally flat with white fluffy aerial mycelium, becoming light brown to olive-green mycelium with age, marginal area irregularly, with yellowish cream conidial drops exuding from the ostioles.

China, Zhejiang Province: Hanzhou City, on branches of Celtis vandervoetiana, 12 May 2018, Q. Yang & Y.M. Liang (holotype BJFC-S1616; ex-type living culture: CFCC 53074; living cultures: CFCC 53075 and CFCC 53076).

Three strains representing Diaporthe celticola cluster in a well-supported clade (ML/BI = 100/1), and appear closely related to D. acaciigena. Diaporthe celticola can be distinguished based on ITS, cal, his3, tef-1α, and tub2 loci from D. acaciigena (29/473 in ITS, 68/442 in cal, 53/460 in his3, 79/330 in tef-1α, and 49/415 in tub2). Morphologically, D. celticola is characterised by conidiomata with single necks erumpent through the host bark and can be distinguished from D. acaciigena by smaller alpha conidia (6–7 × 3.5–4 vs. 10–11 × 6–6.5 μm) (Crous et al. 2011). This is the first occasion that Diaporthe species have been discovered from infected branches on Celtis vandervoetiana and demonstrates it to be a new species based on phylogeny and morphology.

See Udayanga et al. (2014b).

China. Beijing: Pinggu District, on branches of Populus × xiaohei, 10 July 2020, Q. Yang (CSUFT101; living cultures: CSUFTCC101, CSUFTCC102, and CSUFTCC103).

Diaporthe eres is the type species of the genus and was originally described by Nitschke (1870), from Ulmus sp. in Germany, which has a widespread distribution and a broad host range as an endophyte or saprobe, or pathogen causing leaf spots, stem cankers and diseases of woody plants (Udayanga et al. 2014b). In the present study, three isolates (CSUFTCC101, CSUFTCC102, and CSUFTCC103) are embedded into the D. eres species based on DNA sequence data (Fig. 1). We therefore describe D. eres as a known species for this clade.

Distinguished from the phylogenetically closely-related species, D. podocarpi-macrophylli, in shorter alpha conidia.

Figure 3. 

Diaporthe meliae (BJFC-S1668) a, b habit of conidiomata on twig c transverse section through conidiomata d longitudinal section through conidiomata e, f conidiogenous cells g alpha conidia. Scale bars: 1 mm(b); 200 μm (c, d); 10 μm (e–g).

Named after the host genus on which it was collected, Melia.

Conidiomata pycnidial, immersed in the host bark, scattered, erumpent through the bark surface, discoid, with a single locule. Ectostromatic disc dark brown, one ostiole per disc, (325–)330–375(–385) μm (n = 30) diam. Locule undivided, 420–640 × 385–515 μm (n = 30). Conidiophores reduced to conidiogenous cells. Conidiogenous cells (13.5–)15–26.5(–28) × 1.3–2.1(–2.3) μm (n = 30), L/W = 8.5–15.5, cylindrical, hyaline, branched, straight or slightly curved, tapering towards the apex. Alpha conidia hyaline, aseptate, fusiform, multi-guttulate, (6.7–)8–9.5(–10) × (2–)2.1–2.3 μm (n = 30), L/W = 3.4–4.5. Beta conidia not observed.

Colony originally flat with white felty aerial mycelium, becoming auburn furcate mycelium with age, with irregular margin, conidiomata absent.

China, Shandong Province: Rizhao City, on branches of Melia azedarach, 20 April 2018, N. Jiang (holotype BJFC-S1668; ex-type living culture: CFCC 53089; living culture: CFCC 53090).

Two strains representing Diaporthe meliae cluster in a well-supported clade (ML/BI = 100/1), and appear closely related to D. podocarpi-macrophylli. Diaporthe meliae can be distinguished based on ITS, his3, tef-1α, and tub2 loci from D. podocarpi-macrophylli (4/459 in ITS, 15/455 in his3, 25/349 in tef-1α, and 14/401 in tub2). Morphologically, D. meliae can be distinguished from D. podocarpi-macrophylli by its longer conidiogenous cells (15–26.5 vs. 6–18 μm) and alpha conidia (8–9.5 vs. 3.5–8.5 μm) (Gao et al. 2017).

See Yang et al. (2021a).

China, Jiangxi Province: Ganzhou City, on branches of Citrus maxima, 11 May 2018, Q. Yang, & Y.M. Liang (BJFC-S1615; living cultures: CFCC 53098, CFCC 53099, and CFCC 53100).

Figure 4. 

Diaporthe multiguttulata (BJFC-S1615) a, b habit of conidiomata on twig c transverse section through conidiomata d longitudinal section through conidiomata e–g conidiomata formed on PDA h conidiogenous cells i alpha conidia g beta conidia. Scale bars: 200 μm (b–d); 10 μm (h–j).

Diaporthe multiguttulata is characterised by ellipsoidal alpha conidia with one large guttulate, and was originally described as an endophyte from healthy branch of Citrus grandis in Fujian Province, China (Huang et al. 2015). Yang et al. (2021a) identified three isolates from Citrus maxima as D. multiguttulata based on DNA sequence data and confirmed from the morphological characters. In the present study, isolates (CFCC 53098, CFCC 53099, and CFCC 53100) from an additional specimen were observed and supplemented with beta conidia (Fig. 4j).

Distinguished from the phylogenetically closely-related species, D. biguttulata, by its filiform, eguttulate alpha conidia.

Figure 5. 

Diaporthe quercicola (CSUFTCC104) a conidiomata formed on PDA b conidiogenous cells c alpha and beta conidia. Scale bars: 200 μm (a); 10 μm (b, c).

Named after the host genus on which it was collected, Quercus.

On PDA: Conidiomata pycnidial, 250–330 μm diam, globose, solitary or aggregated, deeply embedded in the medium, erumpent, single or clustered in groups of 3–5 pycnidia, coated with hyphae, cream to yellowish translucent conidial droplets exuded from the ostioles. Conidiophores reduced to conidiogenous cells. Conidiogenous cells hyaline, cylindrical, unbranched, straight, tapering towards the apex, (17–)20–26(–34.5) × 2.5–3.5 μm (n = 30), L/W = 6.5–9. Alpha conidia (6.5–)7–8.5(–9) × (1.5–)2–3 μm (n = 30), L/W = 3–4.5, aseptate, hyaline, fusiform, apex at both ends, eguttulate. Beta conidia hyaline, aseptate, filiform, straight or sinuous at one end, eguttulate, (21.5–)25.5–31(–33) × 1 µm (n = 30), L/W = 22.5–31.5.

Colony at first white, becoming dark brown with age. Aerial mycelium white, dense, fluffy, with yellowish conidial drops exuding from the ostioles after 20 days.

China. Shaanxi Province: Xian City, on branches of Quercus aliena, 10 July 2020, Q. Yang (holotype CSUFTCC104; ex-type living culture: CSUFTCC104; living cultures: CSUFTCC105 and CSUFTCC106).

Three strains representing Diaporthe quercicola cluster in a well-supported clade (ML/BI = 100/1), and appear closely related to D. biguttulata. Diaporthe quercicola can be distinguished based on ITS, his3, and tef-1α loci from D. biguttulata (8/461 in ITS, 18/448 in his3, and 22/325 in tef-1α). Morphologically, D. quercicola can be distinguished from D. biguttulata by its fusiform, eguttulate alpha conidia and narrower beta conidia (1 vs. 0.9–1.6 μm) (Huang et al. 2015).

Distinguished from the phylogenetically closely-related species, D. hongkongensis, in narrower beta conidia.

Figure 6. 

Diaporthe rhodomyrti (BJFC-S1660) a conidioma formed on PNA b conidiogenous cells c alpha and beta conidia. Scale bars: 500 μm (a); 10 μm (b, c).

Named after the host genus on which it was collected, Rhodomyrtus.

On PNA: Conidiomata pycnidial, 500–850 μm diam, globose or rostrate, black, erumpent in tissue, erumpent at maturity, often with translucent conidial drops exuding from ostioles. Conidiophores reduced to conidiogenous cells. Conidiogenous cells (14.5–)15.5–23(–25.5) × 1.5–2 μm (n = 30), L/W = 8.5–13, cylindrical, hyaline, unbranched, septate, straight, tapering towards the apex. Alpha conidia abundant in culture, hyaline, aseptate, ellipsoidal, biguttulate, 6–7(–8.5) × 2–2.5(–3) μm (n = 30), L/W = 2.8–3.3. Beta conidia hyaline, aseptate, filiform, straight to sinuous, eguttulate, (15–)16.5–21.5(–23) × 1–1.5 µm (n = 30), L/W = 15.5–16.5.

Colony entirely white at surface, reverse with pale brown pigmentation, white, fluffy aerial mycelium.

China. Jiangxi Province: Ganzhou City, on leaves of Rhodomyrtus tomentosa, 10 May 2018, Q. Yang & Y.M. Liang (holotype BJFC-S1660; ex-type living culture: CFCC 53101; living culture: CFCC 53102).

This new species is introduced as molecular data, and shows it to be a distinct clade with high support (ML/BI = 100/1) and appears closely related to Diaporthe hongkongensis. Diaporthe rhodomyrti can be distinguished based on ITS, cal, his3, tef-1α, and tub2 loci from D. hongkongensis (2/463 in ITS, 26/441 in cal, 11/434 in his3, 10/327 in tef-1α, and 2/420 in tub2). Morphologically, D. rhodomyrti can be distinguished from D. hongkongensis by its longer conidiogenous cells (15.5–23 vs. 5–12 μm) and narrower beta conidia (1–1.5 vs. 1.5–2 μm) (Gomes et al. 2013). This is the first time that Diaporthe species has been discovered from infected leaves on Rhodomyrtus tomentosa and demonstrate it as a new species based on phylogeny and morphology.