Topeliopsis scopulana Kantvilas, 2025

Topeliopsis scopulana Kantvilas , sp. nov. ( Figs 4E View FIGURE 4 , 8B View FIGURE 8 )

MycoBank #MB 860372

A saxicolous species with a continuous greyish white thallus to 0.5 mm thick, lacking lichen substances, persistently immersed apothecia, 2-spored asci, and hyaline, richly muriform, ellipsoid, intensely amyloid ascospores, 44–110 × 13–34 µm, with (8–)10–15 transverse and 1–4 longitudinal septa.

Type: — AUSTRALIA. Tasmania, Cape Pillar, 43°13’S 147°59’E, 290 m, on sheltered dolerite rocks along cliff edge, 5 April 2012, G. Kantvilas 284/12 ( holotype — HO 565303).

Thallus crustose, rimose-areolate, verruculose, greyish white, forming extensive continuous patches, unevenly to c. 0.5 mm thick, with a rather scurfy and abraded surface; medulla I + violet in the vicinity of the apothecia, elsewhere I –, lacking calcium oxalate; photobiont Trentepohlia , with cells globose to ellipsoid, 8–18 × 7–14 µm, in short chains. Apothecia 0.3–0.8 mm wide, deeply and persistently immersed in the thallus and visible as a round, ostiole-like pore, initially c. 0.05 mm wide, at length widening to c. 0.5 mm; disc mostly obscured throughout development by over-arching thalline and excipular tissues, pale grey-pruinose; proper exciple fused to the thallus, whitish, cracked and abraded, in section 50–60(–100) µm thick in the upper part, indistinctly paraplectenchymatous, reddish brown, unchanged in K at the inner and outer edges, hyaline and I + violet within, basally pale reddish brown, 20–30 µm thick; periphyses 15–30(–40) µm long, 1.5–2 µm thick. Hypothecium hyaline, 15–20 µm thick. Hymenium hyaline, non-amyloid, not inspersed, 140–180 µm thick; asci narrowly cylindrical to clavate ( c. 105 × 35 µm but only one intact ascus seen), 2-spored, non-amyloid, with a slightly thickened apex when young; paraphyses simple, c. 1 µm thick, straight to somewhat wavy, with apices unexpanded. Ascospores (44–)50– 75.2 –97(–110) × (13–)17– 25.0 –32(–34) µm ( n = 25), hyaline, richly muriform, ellipsoid, thinly halonate, intensely I + purple, with (8–)10–15 transverse and 1–4 longitudinal septa; locules rhomboid, 4–7 µm wide; wall to 4 µm thick. Pycnidia immersed, very rare; conidia ellipsoid, 3–5 × 1–1.5 µm.

Chemistry: —no substances detected by TLC.

Etymology: —The species derives from the Latin scopulus (meaning a cliff) and refers to the habitat of the new taxon.

Remarks: —The combination of diagnostic characters of this new species, in particular the the saxicolous, littoral habitat, the thick, continuous thallus, the small, persistently immersed apothecia, 2-spored asci and large, amyloid, muriform ascospores, is unique for the genus Topeliopsis . The closest known species, based on a survey of literature (e.g. Mangold et al. 2009; Rivas Plata et al. 2010), appears to be T. azorica (P.James & Purvis) Coppins & Aptroot , but that taxon has prominent, emergent, subglobose apothecia, as illustrated by Purvis & James (1993) and Mangold et al. (2009). The habitat of T. scopulana is highly unusual for a genus that is mostly associated with moist, montane or temperate habitats and usually grows over bark, bryophytes or dead plant material. As such, it is ascribed to this genus with some caution. However, this lichen is clearly very rare and highly unusual, and deserves placement in a genus of best fit if only to bring it to the attention of researchers in the future.