Diaporthe pyracanthae L. Santos & A. Alves, Mycosphere 8: 493 (2017)
Index Fungorum number: IF 820224; MycoBank number: MB 820224; Facesoffungi number: FoF 09198; Fig. 1
Associated with foliar lesions. Sexual morph Undetermined. Asexual morph Conidiomata pycnidial, stromatic, solitary, subglobose to pyriform, dark-brown to black, thickwalled, 600 µm diam., mostly glabrous, but often covered with hyphal outgrows, superficial, opening via a central ostiole, internal cavity heart-shaped, exuding a pearl mucoid mass of conidia. Pycnidial wall pseudoparenchymatous of dark-brown, paler on the apex or around the ostiole, thin-walled textura angularis, becoming hyaline towards the inner layers. Conidiophores absent. Conidiogenous cells lining the entire cavity, lining the entire cavity, 5.9–22.6×1.5–3.4 µm (mean±SD =12.54±3.47 × 2.09±0.42 µm), straight or curved, hyaline, smooth- and thin-walled, cylindrical, occasionally ampulliform, tapering towards the apex, aseptate, rarely 1-septate, with a small branch below the septum, phialidic, collarette minute, enteroblastic, proliferating at the same level giving rise to periclinal thickenings. Alpha conidia fusiform to ellipsoidal, with both ends rounded or one end subobtuse, hyaline, smooth- and thin-walled, aseptate, mostly aguttulate, often with two inconspicuous guttules, not produced on PDA, on autoclaved palm leaf pieces 5–6.4×1.8–2.9 µm (mean±SD=5.77±0.34×2.39±0.22 µm); mean±SD conidium length/width ratio=2.43±0.26. Beta conidia filiform, mostly hooked at the apex, base truncate, apex acute and tapered, hyaline, smooth- and thin-walled, aseptate, aguttulate, 21.6–32.1×0.9–1.8 µm (mean ±SD=27.47±1.91×1.28±0.17 µm); mean±SD conidium length/width ratio=21.82±3.34. Gamma conidia not seen.
Culture characteristics – Colonies on PDA, reaching 55 mm diam. after 7 d at 20 ℃. Surface flat, sparse aerial mycelium in raised concentric circles, with irregular margin, circular to irregular, white, pale-brown to yellowish towards the centre, opaque. Reverse luteous, buff to marron towards the centre. No diffusible pigment. Conidiomata black, scattered over the surface of the colony.
Material examined – PORTUGAL, Lisbon, Parque das Nações, Jardins Garcia d’Orta, Talhão do Coloane, on foliar lesions of segments of Chamaerops humilis (Arecaceae), 16 October 2018, D.R.S. Pereira (specimen HDP 039/02, living culture CDP 052).
Distribution – Portugal, Aveiro (Santos et al. 2017), Lisbon (present study).
Hosts – Pyracantha coccinea (Santos et al. 2017), Chamaerops humilis (present study).
GenBank number – CAL=MT011066, ITS=MT002843, TEF1-α=MT011070, TUB2=MT011076.
Notes – Diaporthe pyracanthae was introduced by Santos et al. (2017) for a collection on Pyracanthus coccinia in Portugal and since then it has not been reported on any other hosts. One isolate of D. pyracanthae was recorded from foliar lesions of palms, but pathogenicity has not been tested (Figs. 1 and 2). This is the first time that D. pyracanthae is reported from Arecaceae, namely Chamaerops humilis, representing a new host record.
Figure 1 – Diaporthe pyracanthae (CDP 052, new record). a Conidiomata formed on 1/2 PDA. Conidia are oozing in pearl mucoid masses. b Vertical section of conidioma, showing its heart-shaped internal cavity. c–g Conidiogenous cells. h, i Beta conidia. j, k Alpha conidia. Scale bars: a=0.5 mm, b=20 µm, c–k=5 µm
Figure 2 – Maximum Likelihood tree generated by RAxML with GTR+G+I nucleotide substitution model using the combined four loci ITS, TEF1-α, TUB and CAL. The sequences were retrieved from GenBank according to BLAST searches with the ITS locus and by reference to the recent literature. Sixty-four strains are included in the combined analyses that comprise 2248 characters (including gaps) (502 characters for ITS, 669 for TUB, 411 for TEF1-α and 554 for CAL) after alignment and manual adjustment. The final likelihood score for the ML tree was − 15269.024241. The matrix had 1121 distinct alignment patterns, with 27.31% undetermined characters or gaps. ML bootstrap support values (>50%) are shown above the branches. The scale bar represents the expected number of nucleotide changes per site. Diaporthe toxica (CBS 534.93) was included as an outgroup. Ex-type/ex-epitype/ex-isotype/ex-neotype cultures are in bold and newly generated sequences are in blue