Paraphaeosphaeria sporulosa (W. Gams & Domsch) Verkley, Göker & Stielow, Persoonia 32: 47 (2014)

Index Fungorum number: IF 800768; MycoBank number: MB 800768; Facesoffungi number: FoF 12739; Fig. 1

Saprobic on driftwood in the intertidal zone. Sexual morph: Undetermined. Asexual morph: Coelomycetous. Mycelium mostly immersed, composed of septate, branched, hyphae. Conidiomata 110–170 × 140–220 µm (x=139×175 µm, n=10) diam., pycnidial, solitary, globose, superficial or semi-immersed, glabrous, dark brown to black, thin-walled, unilocular, ostiolate. Ostiole up to 45 µm long, circular, papillate, laterally or centrically located. Conidiomatal wall 10–30 µm, composed of thick-walled, dark brown to hyaline cells of textura angularis, lined by a thin layer of globose hyaline cells. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 5.5–10×2–4 µm (x=7.7×3.1 µm, n=20) subglobose to ampulliform, swollen at the base, hyaline, enteroblastic, phialidic, with periclinal thickening or percurrent proliferation at apex, smooth, thin-walled. Conidia 3–5.5×2–3.5 µm (x=4.1×2.7 µm, n = 50), highly variable in shape, subglobose, ellipsoid, obovoid-pyriform, initially hyaline, after secession olivaceous-brown, aseptate, smooth, thin-walled, with one large (1.4–2.5 µm diam.) and often also 1–2 additional smaller oil-droplets (1–1.5 µm).

Culture characteristics – Conidia germinating on malt extract agar (MEA) within 24 h. Germ tubes produced around conidium. Colonies growing on MEA, reaching 30–35 mm in 2 weeks at 25 °C, colony circular, flat, entire to filiform edge, dry, surface rough, white in top view, reverse white.

Material examined – Sweden, Sudersand, on driftwood in a sandy beach, 7 March 2019, E.B. Gareth Jones, GJ660B (MFLU 22-0118, new geographical record).

Hosts and geographical distribution – France, Germany, Netherlands (Verkley et al. (2014); China (Wu et al. 2013); Sweden.

GenBank numbers – ITS: OP216407, LSU: OP216402, rpb2: OP251196, tef1-α: OP251192 

Notes – BLASTn results of the LSU, ITS, and rpb2 sequence data of our isolate (MFLU 22-0118) showed a high similarity with Paraph. sporulosa and Curreya pityophila. Hence, Curreya pityophila strains were included in the phylogenetic analysis. Multi-locus phylogenetic analyses revealed that our isolate grouped with Paraph. sporulosa and Curreya pityophila (CBS 149.32, CBS 986.69, UTHSC: DI16–357) with ML=99%, BI=1.00 statistical support (Fig. 2). Morphological data of Curreya pityophila strains CBS 149.32, CBS 986.69, UTHSC: DI16-357 are not available and hence, morphological comparison between our collection and Paraph. sporulosa is not possible. Even though, Curreya pityophila clustered with Paraph. sporulosa, its sexual morph does not conform with the generic description of Paraphaeosphaeria wherein ascospores are cylindrical to elliptical, 1–10-septate with broadly rounded apex and tapering to a more narrowly rounded base. Curreya pityophila has an oblong ascospores with 3–5-transverse septa constricted at the middle septum (von Arx and Muller 1975; Ariyawansa et al. 2014b). With morphological differences, we will retain Curreya pityophila as a distinct species. The relationship between these two taxa warrants further morphological observations of C. pityophila with molecular information and obtaining the sequence data of the type specimen of C. pityophila.

Figure 1 – Paraphaeosphaeria sporulosa (MFLU 22-0118). a Examined material. b Conidiomata on the substrate. c Vertical section of conidioma. d Conidioma wall. e Conidiogenous cells and developing conidia. f, g Conidia. h Germinated conidium. i Surface view of colony on MEA. j Reverse view of culture on MEA. Scale bars: b=200 µm, c=50 µm, d–f=10 µm, g, h=5 µm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU, SSU, ITS, rpb2, tef1-α, and β-tubulin sequence data representing the species of Didymosphaeriaceae. Periconia byssoides (H 4432) and P. pseudobyssoides (H 4151) were used as the outgroup taxa. Seventy-three taxa are included in the combined analyses which comprised 4907 characters (LSU=1339, ITS=412, SSU=900, tef1-α=687, rpb2=1,100, β-tubulin=450) after alignment. The best scoring RAxML tree with a final likelihood value of−25,918.844688 is presented. The matrix had 1440 distinct alignment patterns, with 56.15% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.239744, C=0.250490, G=0.271816, T=0.237951; substitution rates: AC=1.420690, AG=2.626732, AT=1.570948, CG=0.994736, CT=5.458583, GT=1.0; gamma distribution shape parameter α=0.332015. Bootstrap support for ML equal to or greater than 70% and BI equal to or greater than 0.90 are given above the nodes. Extype strains are in bold and newly generated sequences are in blue bold