Seiridium rosarum Wanas., Camporesi, E.B.G. Jones & K.D. Hyde, in Wanasinghe et al., Fungal Diversity: 10.1007/s13225-018-0395-7,  (2018)
Index Fungorum number: IF 554225; Facesofungi number: FoF 04068
Etymology: The specific epithet reflects the host genus Rosa.
Holotype: MFLU 16-0247.
Saprobic on spines and branches of Rosa canina. Sexual morph: Undetermined. Asexual morph: Conidiomata 80–110 μm high 250–300 μm diam. (x̄ = 94.9 × 275.1 μm, n = 5), pycnidial to sporodochial, mostly solitary, immersed, unilocular, conic or subglobose with flattened base, dark brown to black. Conidiomata wall 5–10 μm thick at sides, not well defined, comprising brown, thin-walled cells of textura angularis, with lighter cells at the base fusing into the host tissue. Conidiophores 20–50 × 1.5–2.5 μm (x̄ = 42.3 × 2.1 μm, n = 40), septate, cylindrical, relatively long and irregularly branched, hyaline or pale brown, thinwalled. Conidiogenous cells 5–20 × 1.5–3 lm (x̄ = 15.7 × 2.2 μm, n = 40), discrete, hyaline, cylindrical, smooth- and thin-walled, proliferating percurrently, with visible collarettes and minute periclinal thickenings. Conidia 22–28 × 7–9 μm (x̄ = 25.9 × 7.8 μm, n = 40), lunate to falcate, curved, 5-septate, rarely 4- or 6-septate, not striate, bearing one appendage, euseptate with no visible pores, basal cell obconic with a truncate base, hyaline, walls smooth, 3.5–4 μm; four median cells, smooth, cylindrical to doliiform, brown to dark brown, and septa darker than the rest of the cells, second cell from base 5–6 lm long, third cell 5–6 μm long, fourth cell 5–6 μm long, fifth cell 4.5–5.5 μm long, apical cell conical, hyaline, smooth, 3.5–4 μm long, apical appendage single, mostly centric, up to 12 μm long.
Material examined: ITALY, Forli-Cesena Province, near Pietrapazza, Bagno di Romagna, on dead aerial spines and branches of Rosa canina L. (Rosaceae), 13 March 2015, Erio Camporesi IT 2412 (MFLU 16-0247, holotype), living culture MFLUCC 17-0654.
GenBank: ITS: MG828961, LSU: MG829072
Notes: Seiridium rosarum is morphologically similar to S. eucalypti and S. unicorne in having conidia with similar conidial dimensions (length/width ratio), smooth-walled median cells and unbranched appendages and lacking spathulate ends. The conidiomata of S. unicorne are occasionally plurilocular or have irregularly convoluted locules and their spores bear one apical and basal appendage (Nag Raj 1993), while the conidiomata of S. rosarum are unilocular producing conidia with one apical appendage. Seiridium eucalypti is foliicolous, having stromatic conidiomata.