TASMIDELLA ^{1 2}

Gintaras Kantvilas ³

Tasmidella Kantvilas, Hafellner & Elix, Lichenologist 31: 214 (1999).

Type: T. variabilis Kantvilas, Hafellner & Elix [= T. subfuscescens (Hellb.) Kantvilas]

Thallus crustose, ecorticate. Photobiont a unicellular green alga with globose cells 6–13 µm wide. Ascomata apothecia, biatorine, sessile, basally constricted. Proper exciple in section annular, persistent or becoming ± excluded, composed of radiating, branched and anastomosed hyphae to 2 µm wide, densely inspersed with oil droplets to 20 µm wide. Hypothecium hyaline to pale yellowish, likewise inspersed. Hymenium hyaline, not inspersed, bluish-green, N+ crimson pigment in the upper part, overlain by pale brown, angular granules insoluble in K. Paraphyses simple, not capitate, separating freely in K. Asci broadly clavate, 8-spored, with a well-developed, amyloid tholus penetrated by a non-amyloid, masse axiale with convergent flanks; ocular chamber not developed. Ascospores mostly simple, very rarely 1-septate, hyaline, with a distinct, clearly 2-layered wall. Conidiomata pycnidia, immersed, inconspicuous, with a hyaline wall. Conidia filiform, 12–14 × 1 µm. Chemistry: atranorin only or xanthones.

A genus of two, chiefly chemically differentiated, epiphytic species, found in cool temperate habitats in Australasia. With its usually black apothecia, Tasmidella is superficially similar to a number of other crustose genera that occur in similar situations, such as Lecidella, Megalaria and Sarrameana. It is distinguished from these by the unique combination of its ascus-type, exciple structure and, in particular, the double-walled, 0(–1)-septate ascospores. Its taxonomic position remains unclear (Kistenich et al. 2018).

Key references: Kantvilas et al. (1999); Kantvilas (2023).

1	Thallus dull yellowish, containing xanthones (K–, C+ orange, UV+ orange-pink); apothecia frequently becoming convex and immarginate with age; disc typically epruinose	2 T. subfuscescens
	Thallus pale cream or grey, containing atranorin only (K+ yellowish, C–, UV–); apothecial margin persistent; disc mostly plane and thinly bluish grey-pruinose	1 T. inactiva

1 Tasmidella inactiva (Kantvilas, Hafellner & Elix) Kantvilas

Muelleria 42: 4 (2023); —Tasmidella variabilis var. inactiva Kantvilas, Hafellner & Elix, Lichenologist 31: 220 (1999). Type: Tasmania, Hartz Mountains National Park, Lake Osborne Track, 43°13’S 146°45’E, on Nothofagus cunninghamii in subalpine woodland, 820 m, 9 August 1981, G. Kantvilas 488/81 & P. James (holo—HO!; iso—BM!, GZU!).

Thallus smooth, rimose-areolate to weakly verruculose, pale cream or grey, to 250 µm thick but frequently much thinner, esorediate, forming diffuse patches to c. 5 cm wide; prothallus usually present, effuse, bluish black, visible at the thallus periphery or where the thallus is thin or discontinuous. Apothecia 0.5–1.5(–2) mm wide; disc most commonly black to grey-black, thinly bluish grey-pruinose, sometimes pale brownish and epruinose, occasionally piebald, mostly plane, or becoming undulate to convex; proper exciple prominent and persistent, glossy black, in section 70–120 µm thick laterally, blue-green, K+ olive-green, N+ crimson at the upper edge, brownish at the sides, becoming weakly pigmented to hyaline within, sometimes with traces of additional violet, K+ vivid turquoise pigment; pigments deposited between (and not within) the hyphae. Hypothecium often patchily I+ violet, 90–200 µm thick, densely inspersed with oil droplets. Hymenium 60–100 µm thick; paraphyses (1–)1.5–2 µm thick, with apices generally unthickened or to 2–2.5 µm wide; asci 50–70 × 15–30 µm. Ascospores straight or occasionally slightly curved, ellipsoid, (12–)13.5–16.4–20(–22.5) × 7–8.0–10 µm; wall 1–1.5 µm thick. Pycnidia not found.

Chemistry: atranorin and chloroatranorin; thallus K+ yellowish, KC–, C–, P–, UV–.

Known from Tasmania and New Zealand, where it occurs as an epiphyte on the smooth bark of young trees in high-elevation rainforest, subalpine woodland and scrub. The grey thallus and thinly marginate, lightly pruinose apothecia are very distinctive. Epruinose individuals with a dull-coloured thallus can be more problematic to distinguish from T. subfuscescens.

The Gap, Florentine Road, 42°43’S 146°29’E, 600 m, 1997, G. Kantvilas 266/97 (HO, MSC); Lots Wife, 42°57’S 146°28’E, 1070 m, 2000, G. Kantvilas 469/00 (HO); Lake Skinner Track, 42°57’S 146°41’E, 910 m, 2014, G. Kantvilas 470/14 (HO).

2 Tasmidella subfuscescens (Hellb.) Kantvilas

Muelleria 42: 5 (2023); —Biatora subfuscescens Hellb., Bih. Kongl. Svenska Vetensk.-Akad. Handl., Afd. 3 21 (no. 13): 104 (1896).

Tasmidella variabilis Kantvilas, Hafellner & Elix var. variabilis, Lichenologist 31: 214 (1999). Type: Tasmania, c. 4 km E of McPartlan Pass, 42°51’S 146°14’E, on Banksia marginata in open Eucalyptus nitida-dominated woodland, 360 m, 5 December 1995, G. Kantvilas 186/95 (holo—HO!; iso—GZU!).

Anatomically identical to T. inactiva but differing by containing xanthones, and with a generally coarser, more verruculose, dull yellowish thallus. The black, pale brown or piebald apothecial disc is rarely pruinose, frequently becomes convex with age, and the margin is excluded; new apothecia are frequently seen regenerating on the disc of old, moribund apothecia. The ascospores are (13–)14–16.7–21(–22) × 6–6.9–8 µm.

Chemistry: thiophanic acid and arthothelin; thallus K–, KC–, C+ orange, P–, UV+ orange-pink.

Widespread and very common in Tasmania where it occurs in wetter areas from sea-level to alpine elevations. The dull yellowish thallus with abundant black or brownish-piebald apothecia is very distinctive. It occurs on bark, wood and dead Richea pandanifolia leaves, with particularly common habitats including the trunks and branches of Banksia marginata in buttongrass moorland, and the twigs and small branches of alpine shrubs. The most intensely pigmented apothecia are found in the most exposed, sunniest habitats; in deep shade the apothecia are frequently flesh-coloured. On Richea leaves the thallus tends to be very thin and smooth, and the apothecia are jet-black. This species is also known from Victoria and New Zealand.

Lake Esperance, 43°14’S 146°46’E, 980 m, 1963, P.W. James (BM, HO); Sphinx Bluff, 41°37’S 147°44’E, 1370 m, 1996, G. Kantvilas 15/96 (HO); Shipstern Bluff, 43°12’S 147°45’E, 80 m, 2011, G. Kantvilas 181/11 (HO).

References