Rossmaniella tylophori Darmostuk & Flakus 2025, sp. nov.

Rossmaniella tylophori Darmostuk & Flakus, sp. nov. MycoBank MB 858388. Figs 3H, 10. Etymology: Named after the host lichen genus, Tylophoron. Typus: Bolivia, Chuquisaca Department, Luis Calvo Province, Iñao National Park and Integrated Management Natural Area, between Ticucha and Entre Ríos, 19º31’09”S, 63º53’31”W, 1373 m a.s.l., disturbed area with shrubs, on corticolous Tylophoron protrudens, 19 Jul. 2015, A. Flakus 26805 (holotype KRAM L-74687, isotype LPB) Ascomata perithecioid, ovoid to pyriform, superficial, solitary, lemon yellow, (200–)230–270(–300) × (150–)160–175(– 185) µm (n = 15), covered by not dense whitish tomentum, composed of simple to branched, hyaline, septate, thin-walled, verruculose hyphae, 4–5 μm thick. Ascomata surface evenly coloured, without hairs near ostiole part. Ascomatal wall 18–25 μm thick, slightly thicker at the upper part, hyaline to pale yellow, composed of two layers: an external layer of globose, thin-walled cells, 2–4 × 2–3 μm; an inner region of flattened, thin-walled cells, 3–12 × 1–2 μm, KOH–. Asci cylindrical, without apical thickness, 8-spored, (170–)175–180(–200) × (12.6–)13.0–13.8(–14.2) µm (n = 15). Ascospores hyaline, 8–12-septate, filiform, straight or rarely slightly curved, parallel to rarely twisted in the ascus, both ends rounded, (125–)140–155(–180) × (2.8–)3.4–4.4(–4.6) μm (n = 30), individual cells (10.0–)12.0–15.6(–16.8) μm (n = 30) long. Conidiomata not observed. Distribution, habitat and host range: This species is known only from the type locality in Bolivia. This fungus grows on corticolous Tylophoron protrudens and the infection does not cause visible damage to the host thallus. Notes: Rossmaniella tylophori can be distinguished from other Rossmaniella species by solitary lemon-yellow ascomata, shorter and wider ascospores and host specificity. However, since the species is known only from a single collection, the host range is unknown. Previously only two lichenicolous species were reported on Tylophoron species, i.e. Taeniolella serusiauxii reported from Europe and tropical regions (Heuchert et al. 2018) and Chaenothecopsis pilosa described from Tanzania (Tibell & Ryman 1995).