Keissleriella rosacearum Phukhams., Camporesi & K.D. Hyde, in Wanasinghe et al., Fungal Diversity: 10.1007/s13225-018-0395-7,  (2018)
Index Fungorum number: IF554138; Facesofungi number: FoF 03977
Etymology: specific epithet reflects the host genus Rosa.
Holotype: MFLU 15-1044.
Saprobic on Rosa. Sexual morph: Ascomata 165–240 μm high × 145–254 μm diam. (x̄ = 181 × 179 μm, n = 10), black, immersed, solitary or gregarious, fully or partly erumpent, globose, uniloculate. Ostiole papillate, 31–56 μm long, 29–50 μm wide, covered with 1-celled, thick walled, reddish-brown to blackish-brown setae. Peridium 8–30 μm wide at the base, comprising 2 layers, outer most layer heavily pigmented, thick-walled, comprising reddish to dark brown cells of textura angularis, inner layer composed of hyaline, flattened, thick walled cells of textura angularis. Hamathecium comprising numerous, 1.5–3 μm (n = 50) wide, filamentous, branched septate, pseudoparaphyses. Asci 56–120 × 10–14 μm (x̄ = 71 × 11 μm, n = 50), 8-spored, bitunicate, fissitunicate, clavate to cylindrical, pedicellate, rounded at the apex and with a shallow ocular chamber. Ascospores 18–25 × 5–6 μm (x̄ = 20 × 6 μm, n = 50), overlapping biseriate, narrowly fusiform, with 3 septa, median septum nearly primary, constricted at the septum, pale-brown, conical and narrowly rounded at the ends, guttulate, surrounded by a thick mucilaginous sheath. Sheath 10–15 μm wide when fresh, delimited when dry. Asexual morph: Undetermined.
Material examined: ITALY, Province of Forli‘-Cesena [FC], near Monte Fumaiolo, on dried aerial spines of Rosa canina L. (Rosaceae), 23 October 2014, Erio Camporesi, IT 2194 (MFLU 15-1044, holotype), ex-type living culture, MFLUCC 15-0045.
GenBank Numbers: LSU: MG829015; SSU: MG829123.
Notes: Based on combined multi-gene phylogenetic analysis, Keissleriella rosacearum nests with other Keissleriella species with low bootstrap support. Keissleriella rosacearum shares some similar characters with K. rosarum in having clavate to cylindrical asci and fusiform, guttulate ascospores with a thick mucilaginous sheath. It differs from K. rosarum in having 3-septate, pale brown ascospores (18–25 9 5–6 μm), whereas K. rosarum has 1-septate, hyaline ascospores (18–22 × 5–8 μm). (****need update note).