Rossmaniella coenogonii Darmostuk, Kukwa & Flakus, 2025

Rossmaniella coenogonii Darmostuk, Kukwa & Flakus , sp. nov. MycoBank MB 858385. Fig 6.

Etymology: Named after the host lichen genus, Coenogonium .

Typus: Bolivia, Cochabamba Department, Carrasco Province, Parque Nacional Carrasco, near Río López Mendoza , 2248 m a.s.l., lower montane Yungas cloud forest, Andino montano (Montano), on corticolous Coenogonium sp. , 27 Nov. 2014, M. Kukwa 15078a (holotype LPB) .

Ascomata perithecioid, ovoid to pyriform, not collapsed when dry, superficial, solitary, pale orange, 300–430 × 185–240 µm (n = 7), ascomata surface fully covered by not dense, whitish, arachnoid tomentum, composed of hyaline, septate, thin-walled, verruculose hyphae, 4–5 μm thick, without papilla in ostiolar region. Ascomatal wall 25–40 μm wide, slightly thicker at the upper part than in the lower part, hyaline to pale yellow, composed of two layers of flattened cells: external layer composed of 3–5 layers of isodiametric, thin-walled cells, 6–8 × 5–6 μm; an inner region with 2–4 layers of elongated thin-walled cells, 9–12 × 2–3 μm, KOH–. Asci narrowly cylindrical, without apical thickness, 8-spored, (175–)180–200(–220) × (8.0–)8.4–10.0(–10.4) μm (n = 10). Ascospores hyaline, (12–)14–16-septate, filiform, mostly curved to sigmoid, parallel to spirally twisted in the ascus, proximal ends rounded, distal end pointed, (170–)180– 200(–210) × (1.8–)2.0–2.6(–3.0) μm (n = 25), individual cells (6.4–)8.0–12.2(–12.8) μm (n = 30) long. Conidiomata not observed.

Distribution, habitat and host range: This lichenicolous fungus is only known from the type locality in the Yungas cloud forest (2200 m a.s.l.) growing on the thallus of corticolous Coenogonium sp. This species likely causes a strong pathogenic effect on the host, forming discoloured infected areas up to 1 cm in size, covered by a whitish, arachnoid tomentum.

Specimen examined of Nectria byssophila : Ceylon, Nuwara Eliya , on mosses on the tree trunk, 19 Jun. 1927, T. Petch (K-M001434927)

Notes: Nectria byssophila s. str. is a poorly known species originally described from Ceylon where was growing on epiphytic mosses ( Petch 1944). Subsequently, this name was commonly used for hypocrealean lichenicolous fungi growing on different hosts with long filiform ascospores and ovoid to pyriform yellow orange ascomata ( Etayo 2003, 2017, Etayo & Sancho 2008). The type specimen ( Fig. 7, K-M001434927) was examined by us and it has a pale orange ovoid ascomata (only seven ascomata observed), mainly scattered, totally covered by whitish tomentum, 300–350 × 200–250 μm (n = 7). Unfortunately, asci and ascospores were not observed. Following the description by Rossman (1983) and macroscopic features, Nectria byssophila exhibits a greater resemblance to Rossmaniella coenogonii than to other species within the genus Rossmaniella . However, a fresh collection is from the type locality in Ceylon is needed to reveal the real relationship of this species to the genus Rossmaniella .

Only two lichenicolous species of the order Hypocreales were previously reported on Coenogonium and both were from tropical regions. The first, Nectriopsis mindoensis , was reported on an undetermined lichen host from Colombia ( Samuels 1988) and the second, Niesslia coenogonii , was described as lichenicolous fungus from Panama on Coenogonium luteum ( van den Boom et al. 2017) .