Keissleriella rosae Jayasiri, Camporesi & K.D. Hyde, in Wanasinghe et al., Fungal Diversity 89: 48 (2018)
Index Fungorum number: IF53943; Facesofungi number: FoF 03815
Etymology: The specific epithet reflects the host genus Rosa.
Holotype: MFLU 15-1397.
Saprobic on Rosa canina. Sexual morph: Ascomata 225–228 μm high, 230–250 μm diam., scattered, gregarious semi-immersed to erumpent through host tissue, becoming superficial, visible as abundant, small black dots on the host surface, uniloculate, globose to subglobose, with dark brown setae of 30–40 × 3–3.5 μm around the ostiole. Peridium 18–30 μm wide, thin-walled, of equal thickness, composed of 5–7 layers of dark brown, broadly pseudoparenchymatous cells, arranged in a textura angularis to textura globulosa. Hamathecium composed of numerous, 2–3 lm wide, filamentous, cellular pseudoparaphyses, with distinct septa, embedded in mucilaginous matrix. Asci 75–85 μm high, 11–15 μm diam (x̄ = 80 × 14 μm, n = 20), 8-spored, bitunicate, fissitunicate, broadly cylindrical to cylindric clavate, subsessile to short pedicellate, apically rounded, with well-developed ocular chamber. Ascospores 20–24 × 5–7 lm (x̄ = 21 × 6 μm), overlapping 1–2 seriate, phragmosporous, ellipsoidal to broadly fusiform, initially hyaline to pale yellowish, becoming light brown to brown or yellowish-brown at maturity, initially forming one median septum, becoming 3–5-septate at maturity, slightly curved, constricted at the septa, smooth and thin–walled. Asexual morph: Undetermined.
Culture characters: Colonies grow on PDA reaching 2 cm diam after 2 weeks at 18 °C, later with dense mycelium, circular, smooth, margin irregular, off white after 2 weeks, reverse pale brown layers to dark brown layers, flat on the surface, with aerial mycelium. Hyphae septate, branched, hyaline, thin-walled.
Material examined: ITALY, Province of Forlı`-Cesena [FC], Converselle, Castrocaro Terme e Terra del Sole, on dead aerial spines of Rosa canina L. (Rosaceae), 25 November 2014, Erio Camporesi IT-2258 (MFLU 15-1397; holotype), ex-type living cultures, MFLUCC 15-0180.
GenBank Numbers: LSU: MG829016; SSU: MG922549.
Notes: Keissleriella rosae is typical of Keissleriella in its ostiolar neck having short dark setae (Munk 1953, Tanaka et al. 2015). Keissleriella rosae is a distinct species in the genus, supported by molecular and morphological characteristics. Keissleriella rosae clustered as sister to K. cirsii and K. taminensis with 99% ML and 1.00 BYPP bootstrap support. Keissleriella rosae differs from K. cirsii and K. taminensis in having yellow to brown ascospores without a mucilaginous sheath (Tanaka et al. 2015, Tibpromma et al. 2017).