Angustimassarina rosarum Tibpromma, Camporesi & K.D. Hyde, in Wanasinghe et al., Fungal Diversity 89: 21 (2018)
Index Fungorum number: IF553939; Facesofungi number: FoF 03964
Etymology: The specific epithet reflects the host genus Rosa.
Holotype: MFLU 15-1477
Saprobic on dead spines of Rosa canina L. Sexual morph: Ascomata 100–150 μm high × 125–165 μm diam. (x̄ = 124 × 143 μm, n = 5), superficial with flat at the base, solitary or in small groups, globose to subglobose, visible as black dots on the host surface, conspicuous at the surface, shiny, without papillate, black. Ostiole crest-like, rounded, papillate, immersed in ascomata, with a pore-like opening. Peridium 10–17 μm wide, thin, 3–5-layered of cells of textura angularis, dark brown to pale brown. Hamathecium 1.8–2.1 μm wide, cylindrical, few, septate, hyaline, attached to the base, longer than asci long, smooth, pseudoparaphyses. Asci 40–102 × 6–13 μm (x̄ = 70 × 10 μm, n = 10), 8-spored, bitunicate, fissitunicate, cylindric-clavate, slightly curved, long with a club-shaped pedicel, with apex rounded with a minute ocular chamber, smooth-walled. Ascospore 16–22 × 4–6 μm (x̄ = 19 × 5 μm, n = 20), overlapping 1–2-seriate, fusiform to ellipsoidal, hyaline, 1-septate at the centre, 4-large guttules, enlarged cell near septate, constricted at the septum, conical at both ends, smooth-walled, surrounded by a thin mucilaginous sheath. Asexual morph: Undetermined.
Culture characteristics: Ascospores germinating on malt extract agar (MEA) within 24 h. Colonies growing fast on MEA, circular, rough, entire edge with dark brown to back, raised on surface media, velvety.
Material examined: ITALY, Forlı`-Cesena Province, Fiumicello di Premilcuore Province, on dead aerial branch and spines of Rosa canina L. (Rosaceae), 7 May 2012, Erio Camporesi, IT334 (MFLU 15-1477, holotype); ex-type living culture, MFLUCC 15-0080, KUMCC 16-0136); ibid. (HKAS94529 bis, paratypes).
GenBank Numbers: ITS: MG828869, LSU: MG828985.
Note: Angustimassarina rosarum is similar to An. acerina however, when compared morphologically ascomata and ascospores in An. acerina are immersed with hyaline ascospores, becoming ochre brown at maturity and 1(–3)-septate (Thambugala et al. 2015) which differs in An. rosarum. In our phylogenetic analysis, Angustimassarina rosarum is related to An. alni, but differs in having immersed to semi-immersed ascomata with fusiform to cylindrical or ellipsoidal-fusiform ascospores, which are widest at the centre (Tibpromma et al. 2017). There are also seven base pair differences in ITS nucleotide sequences between An. rosarum and An. alni. It is worth pointing out that the affinities of our two new Angustimassarina species are still obscure given that there are no reliable support in our phylogeny, but this is a common phenomenon across Pleosporales members.