Diaporthe pseudophoenicicola R.R. Gomes, Glienke & Crous, Persoonia 31: 30 (2013)
Index Fungorum number: IF 803839; MycoBank number: MB 803839; Facesoffungi number: FoF 09161; Fig. 1
Associated with foliar lesions. Sexual morph Undetermined. Asexual morph Conidiomata pycnidial, stromatic, uni- to multi-locular or convoluted, solitary, black, thick-walled, of variable morphology and dimensions, up to 3.5 mm diam., subglobose to pulvinate, sometimes conical or discoid, glabrous or covered with some hyphal outgrows, superficial to semi-immersed, inostiolate, dehiscent by irregular fissures on pycnidial wall, exuding a creamy, pale-luteous mucoid mass of conidia. Pycnidial locules unito multi-chambered, subdivided by invaginations of common pycnidial walls. Pycnidial wall pseudoparenchymatous, composed of oblong to isodiametric thin-walled cells, outer cell layers of textura globulosa, pigmented, dark-brown, inner cell layers of textura angularis, hyaline. Conidiophores absent. Conidiogenous cells lining the entire cavity, 11.7–49.7 × 1.1–3.1 µm (mean±SD =21.99±9.09 × 1.83±0.44 µm), intermingled with paraphyses, straight, hyaline, smooth- and thin-walled, cylindrical, ampulliform, aseptate to 1-septate at the base, unbranched, rarely with 1 branch below the septum, phialidic, collarette rarely present, enteroblastic, proliferating at the same level giving rise to periclinal thickenings, occasionally proliferating percurrently giving rise to 1–2 distinct annellations or enteroblastic proliferating percurrently after the formation of a new conidiogenous cell by apical wall-building. Paraphyses straight or curved at the apex, hyaline, smooth- and thin-walled, aseptate to 1–2-septate, unbranched or rarely branched at the base, extending above conidiogenous cells, up to 60 µm long. Alpha conidia cylindrical to allantoid, often mediumly narrowed, mostly with one end rounded and the other acute or slightly truncate, hyaline, smooth-walled, thin-walled, aseptate, bi-guttulate, with an inconspicuous guttule at each end, 6.4–9.4×2.9–1.5 µm (mean±SD =8 .07±0.80×2.11±0.31 µm); mean±SD conidium length/width ratio=3.91±0.70. Beta and gamma conidia not seen.
Culture characteristics – Colonies on PDA, reaching 42 mm diam. after 7 at 20 ℃. Surface flat to velvety, with filiform margin, circular, whitish to pale, opaque to slightly translucent. Reverse yellowish to pale, becoming buff towards the centre. No diffusible pigment. Conidiomata black, formed in poorly defined concentric rings.
Material examined – PORTUGAL, Lisbon, Parque das Nações, Jardins da Água, Pomar do Mediterrâneo, on foliar lesions of segments of Chamaerops humilis (Arecaceae), 16 October 2018, D.R.S. Pereira (specimen HDP 039/02, living culture CDP 047); PORTUGAL, Lisbon, Parque das Nações, on foliar lesions of leaflets of Phoenix dactylifera (Arecaceae), 16 October 2018, D.R.S. Pereira (specimen HDP 044/01, living culture CDP 358).
Distribution – China (Gao et al. 2017), Iraq (Shalt El Arab), Spain (Mallorca) (Gomes et al. 2013), Portugal (Lisbon) (present study).
Hosts – Chamaerops humilis (present study), Mangifera indica, P. canariensis (Gao et al. 2017), Phoenix dactylifera (Gomes et al. 2013; present study).
GenBank number – CDP 047: CAL = MT011065, ITS = MT002357, TEF1-α = MT011069, TUB2 = MT011075; CDP 358, CAL = MT011067, ITS = MT004743, TEF1-α = MT011073, TUB2=MT011079.
Notes – Diaporthe pseudophoenicicola was first reported on Phoenix dactylifera from Mallorca, Spain (Gomes et al. 2013). Two isolates of D. pseudophoenicicola were recorded from foliar lesions of palms (Fig. 2), but pathogenicity has not been tested (Figs. 1 and 2). This is the first report of this species from Portugal. One of the isolates was recorded from C. humilis and represented a new host record. The other isolate was recorded from P. canariensis, a host it has already been reported on in China (Gao et al. 2017).
Figure 1 – Diaporthe pseudophoenicicola (CDP 047, new record). a, b Conidiomata formed on 1/2 PDA. Conidia are oozing in creamy mucoid masses. c Section through conidioma loculus. d Section through conidioma loculus showing wall invaginations. e Section through conidiogenous layer. f–h Conidiogenous cells and paraphyses (white arrows). i, j Conidia. Scale bars: a=1 mm, b=0.5 mm, c–e=10 μm, f–j=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