IMSHAUGIA ¹

Gintaras Kantvilas ²

Imshaugia S.L.F.Mey., Mycologia 77: 337 (1985).

Type: I. aleurites (Ach.) S.L.F.Mey.

Thallus foliose, rosette-forming, with lobes elongate and flattened, dorsiventral, plane to slightly convex or concave; upper surface greyish, emaculate, lacking cortical hairs, cilia and pseudocyphellae, corticate, with a pored epicortex; lower surface whitish to pale brown, with simple rhizines. Photobiont trebouxioid. Ascomata apothecia, lecanorine, laminal, sessile to shortly pedicellate; disc plane to concave, pale brown; proper exciple cupulate. Paraphyses rather stout, straight, simple; apices slightly swollen. Asci 8-spored, of the Lecanora-type: clavate; tholus well-developed, amyloid, pierced entirely by a narrow, non-amyloid masse axiale with parallel flanks; ocular chamber not developed. Ascospores simple, hyaline, subglobose to broadly ellipsoid. Conidiomata pycnidia, black, laminal or marginal, sessile and protruding from the thallus. Conidia fusiform, with one or two swellings. Chemistry: atranorin in the cortex, with either thamnolic or evernic acids in the medulla.

A genus of three species that inhabit bark or wood, chiefly in highland areas of both hemispheres. Two species occur in Australia.

1 Imshaugia aleurites (Ach.) S.L.F.Mey.

Mycologia 77: 338 (1985); —Lichen aleurites Ach., Lich. Suec. Prodr.: 117 (1799); Parmelia aleurites (Ach.) Ach., Methodus: 208 (1803); Parmeliopsis aleurites (Ach.) Nyl., Lich. Lapp. Orient. 8: 121 (1866).

Thallus tightly adnate, whitish or pale grey, often glossy, to 4 cm wide, often with several adjacent thalli fusing into larger colonies; lobes plane, undulate or weakly pitted, 0.6–1.5(–2) mm wide, discrete, sometimes darkened, rounded or ± truncate at the apices, crowded and imbricate in the thallus centre, isidiate; isidia laminal and marginal, cylindrical, simple or sparsely branched, c. 0.1–0.2 mm tall and 0.05 mm wide, very abundant and forming a subcrustose, granular mass in the centre of the thallus. Apothecia unknown; ascospores reported as 6–9 × 5–6 µm (Moberg & Thell 2011). Pycnidia very rare; conidia fusiform to dumbbell-shaped, (3–)5 × 1 µm.

Chemistry: atranorin and thamnolic acid; medulla K+ yellow, KC–, C–, P+ orange, UV–.

Widespread in cool climates in both hemispheres; highly localised in Tasmania at higher elevations in eastern parts of the island and in the drier, eastern parts of the Central Plateau. It occurs on the dead, decorticated wood of eucalypts and pencil pines in open woodlands. It is easily distinguished from potentially similar species, in particular from Austroparmelina conlabrosa (Hale) A.Crespo et al., which has a similarly granular-isidiose, grey thallus, by the pale undersurface and the presence of thamnolic acid. No fertile material is known from Australia.

Pine Lake, 41°45’S 146°42’E, 1200 m, 1989, G. Kantvilas 191/89 (CANB, HO); South Sister, near summit, 41°32’S 148°10’E, 800 m, 2004, G. Kantvilas 358/04 (HO); c. 0.5 km NE of Mt Jacob, 42°44’S 147°54’E, 400 m, 2001, G. Kantvilas 568/01 (HO).

References