Thelotrema pinicola Kantvilas, 2025

Thelotrema pinicola Kantvilas , sp. nov. ( Figs 4B View FIGURE 4 , 6 View FIGURE 6 )

MycoBank #MB 860369

Distinguished by the combination of lepadinoid apothecia, with generally 8-spored asci and fusiform-ellipsoid, non-amyloid, brown to grey-brown, richly muriform ascospores, 44–130 × 14–30 µm, with c. 20–30 transverse and up to 5 longitudinal septa.

Type: — AUSTRALIA. Tasmania, Twisted Tarn, 42°40’S 146°34’E, 1120 m, on twigs of Athrotaxis cupressoides in coniferous heathland, 18 August 2024, G. Kantvilas 126/24 ( holotype — HO 619651).

Thallus pale to dull grey, greyish brown or pale bronze-brown, smooth and effuse to endophloeodal, ecorticate, c. 40–90 µm thick around the apothecia, forming diffuse, discontinuous patches to c. 5 cm wide, frequently interrupted by other lichens; medulla I + red, sparsely inspersed with calcium oxalate crystals. Apothecia lepadinoid, at first entirely immersed and discernible as round holes c. 0.1–0.35 mm diam. in the thallus surface, becoming semi-emergent, perithecioid, then at maturity hemispherical, broadly adnate, 0.6–1.2 mm wide, scattered or, occasionally, fused together; thalline margin smooth, entire and incurved, with age sometimes becoming erect and abraded at the edges, often mottled pale brownish, in section c. 100–200 µm thick, I + red, inspersed with crystals of calcium oxalate, sometimes containing bark cells; disc plane, pale grey, obscured ± entirely throughout development by the incurved thalline margin and/or the proper exciple; proper exciple whitish, usually with a ragged margin, in section 50–80 µm thick laterally, 20–40 µm basally, hyaline to pale yellowish, I + red; periphyses 25–45 µm long, c. 3 µm thick. Hypothecium 15–20 µm thick. Hymenium 180–220 µm thick, overlain by a brown or greyish epithecial layer unchanged in K; paraphyses 1–1.5 µm thick, with apices not enlarged; asci 8-spored but sometimes with up to 6 spores aborted by maturity, elongate-clavate, 150–220 × 30–50 µm. Ascospores soon becoming brown or grey-brown, densely muriform, with c. 20–30 transverse and up to 5 longitudinal septa, fusiform-ellipsoid, (44–)56– 81.8 –115(–130) × (14–)15– 19.2 –24(–30) µm ( n = 60), non-amyloid; locules irregularly roundish; wall thin and compact, to 0.5–1.5 µm thick, not swelling markedly in K.

Chemistry:—nil.

Etymology: —The specific epithet refers to the habitat of the new taxon on the twigs of two endemic Tasmanian conifers, Athrotaxis cupressoides (Pencil Pine) and A. selaginoides (King Billy Pine) .

Remarks: —Superficially, this species is very similar to T. subdefectum Kantvilas (described below) and T. oleariae , which also occur in alpine to subalpine habitats, albeit on a different host ( Olearia pinifolia ). However, when well developed, the apothecia of T. pinicola tend to be a little larger. The three species differ markedly by their ascospores ( Fig. 4 View FIGURE 4 ): hyaline, muriform and 25–46 × 10–20 µm in the former, and grey-brown to brown, sparingly muriform and 35–78 × 9–15 µm in the latter. The diagnostic characters of the new species, notably the 8-spored asci and large, richly muriform, non-amyloid, grey to brown ascospores, are shared with relatively few other species of the genus (see Mangold et al. 2009; Rivas Plata et al. 2010). For example, the pantropical T. lepadodes Tuck. , which in Australia has been recorded from mangroves and coastal vegetation in Queensland, has 2–8-spored asci and somewhat smaller, submuriform to muriform ascospores, 40–100 × 10–25(–30) µm ( Mangold et al. 2009; Rivas Plata et al. 2010). The widespread corticolous or saxicolous T. saxatile C.Knight develops apothecioid ascomata and has 1–2- spored asci ( Mangold et al. 2009; Lumbsch et al. 2010). Finally, T. monosporum Nyl. , also known only from tropical latitudes, differs from the new species by its significantly smaller apothecia (to 0.6 mm wide) and 1–4-spored asci ( Mangold et al. 2009; Sipman et al. 2012).

This species is known only from Tasmania and appears to be restricted to the dead twigs of both Athrotaxis cupressoides and A. selaginoides , where it occurs on bark, bare wood stripped of bark, and on the retained, dead, woody, scale leaves of its host ( Fig. 7 View FIGURE 7 ). It had been overlooked until very recently, mainly because this particular habitat did not appear to be intrinsically rich or interesting for lichens, especially when considered within a general environment (alpine coniferous woodland) where other microhabitats and substrata provide more enticingly diverse lichen habitats. It was first collected essentially by chance, but has since been found on several occasions and may well prove to be widespread. Its twig habitat is dominated mainly by depauperate or moribund thalli of species that are better developed on other parts of the host tree (small living branches and trunks). The more common associated species include Hypogymnia lugubris (Pers.) Krog , Menegazzia athrotaxidis Kantvilas , M. subtestacea Kantvilas , Mycoblastus campbellianus (Nyl.) Zahlbr. , Pertusaria pertractata Stirt. , Tasmidella subfuscescens (Hellb.) Kantvilas , Tephromela sorediata Kalb & Elix and species of Usnea .

Specimens examined: — AUSTRALIA. Tasmania: Lake Lexie , 41°46’S 146°22’E, 1265 m, 1 January 2025, G. Kantvilas 9/25 ( HO) GoogleMaps ; c. 1 km S of Turrana Heights , 41°46’S 146°23’E, 1270 m, 2 January 2025, G. Kantvilas 19/25 ( HO) GoogleMaps ; Lake Osborne , 43°13’S 146°46’E, 910 m, 26 January 2025, G. Kantvilas 42/25 ( HO) GoogleMaps ; Lake Perry , 43°12’S 146°45’E, 920 m, 26 January 2025, G. Kantvilas 43/25 ( HO) GoogleMaps .