Paraleptosphaeria nitschkei (Rehm ex G. Winter) Gruyter et al., in Gruyter et al, Stud. Mycol. 75: 20 (2012)

            ≡ Leptosphaeria nitschkei Rehm ex G. Winter, Flora, Regensburg 55: 510 (1872)

Saprobic or pathogenic on stems and leaves of herbaceous or woody plants in terrestrial habitats.Sexual morph: Ascomata (296–)328–362 μm high × (406–)420–423 μmdiam. (x = 329 × 416 μm, n = 5), superficial, solitary or scattered, subglobose to obpyriform, dark brown, without subiculum covering the host. Ostiole with protruding papilla.Peridium 38–)45–56(–64) μm wide, comprising several scleroplectenchymatous cell layers, the outer layer heavily encrusted with pigment and often longitudinally striate on the surface, inner layer with flattened, light brown to dark brown cells. . Hamathecium comprising 0.5–1 μm wide, cylindrical to filiform, pseudoparaphyses.Asci (80–)97–102(–107) × 9–10 μm (x̅ = 98 × 9 μm, n = 10), 8-spored, bitunicate, cylindric-clavate, slightly curved, with short, bulbous pedicel, apically rounded, with an ocular chamber (ca. 1– 1.5 μm wide). Ascospores 27–29(–34) × 4.5–6 μm (x̅ = 29 × 5 μm, n = 10), 1–2-seriate, overlapping, hyaline, fusiform and tapering to the ends, 3-euseptate, slightly constricted at the central septum, cell above central septum swollen, straight or slightly curved, thick and smooth-walled, lacking a mucilaginous sheath. Asexual morph: Coelomycetous. Conidiomata 435–455(–475) × (276–)300–330 μm (x̅ = 455 × 305 μm, n = 5), pycnidial, globose to subglobose, solitary, peridium 30–35(–38) μm, thick-walled, scleroplectenchymatous. Conidiogenous cells 3–4 × 5–6 μm, phialidic. Conidia 1.5–2 × (–12)15–20 μm, hyaline, aseptate, cylindrical to filiform.

Material examined: ITALY, Province of Forlì-Cesena

[FC], Passo la Calla, Santa Sofia, on stems of Petasites sp. (Asteraceae), 14 July 2012, E. Camporesi IT563 (MFLU 14–0021, reference specimen), living culture, MFLUCC 13-0688. ITALY, Province of Forlì-Cesena (FC), Monte Falco, on decaying grass stems of Petasites sp., 21 May 2013, E. Camporesi IT648 (MFLU 13–0644), DNA was extracted from the fruiting body).


Fig.Paraleptosphaeria nitschkei(MFLU 13-0644).a, b. Ascomata on host surface. c. Section of ascoma. d. Close up of the peridium. e. Ostiole with periphyses. f. Pseudoparaphyses g-i.Immature and mature asci.j-m.Ascospores.Scale bar: c=60 µm, d-f=10 µm, g-i=20 µm, j-m=5 µm.

Notes: De Gruyter et al. (2013) introduced Paraleptosphaeria to accommodate Leptosphaeria nitschkei and its allied species in the family Leptosphaeriaceae. Munk (1957) treated Leptosphaeria as four sections as section I (Eu-Leptosphaeria), section II (Para-Leptosphaeria), section III (Scleropleella) and section IV (Nodulosphaeria), but section Para-Leptosphaeria is an invalid taxon and it is also a heterogenous group. The section was separated from Eu-Leptosphaeria, which comprised the generic type species L. doliolum (De Gruyter et al. 2013). Leptosphaeria nitschkei was considered as typical of section Eu-Leptosphaeria (Müller and von Arx 1950). Molecular studies, including the present study show that L. nitschkei is only distantly related to L. doliolum. The seperation of Leptosphaeria in sections Eu-Leptosphaeria and Para-Leptosphaeria cannot be upheld from a evolutionary point of view. Section Eu-Leptosphaeria, with L. agnita and L. maculans (Munk 1957), group in Plenodomus. Liu et al. (2015) designated a reference specimen for Paraleptosphaeria nitschkeito provide a stable taxonomy and phylogeny. In the present study we include another collection of Para. nitschkei from Petasites sp., whch we illustrate.Thus we recognise Paraleptosphaeria as a well-supported genus in the family Leptosphaeriaceae based on both morphology and phylogeny.