Pertusaria subventosa
Description : Thallus off-white to greyish white, thick, areolate, surface smooth, sorediate, without isidia. Soralia white, conspicuous, becoming numerous and often confluent centrally, subspherical, to substipitate, 0.5–1.5 mm diam. Apothecia (not seen in NZ material) very rare, disc-like, discs dark-brown, white-pruinose, 0.2–0.5 mm diam., becoming exposed in stipitate apothecia in groups of 1–3. Ascospores 1 per ascus, ellipsoidal, 120–160 × 35–50 μm, wall 1 μm thick.
Chemistry : K+ yellow, C−, KC+ violet, Pd+ yellow; containing lichexanthone (major), thamnolic acid (major) and picrolichenic acid (major) rarely with additional norstictic acid (Archer & Elix 1994b: 25; Archer 1997: 204).
N: Northland (Three Kings Is, Bald Hill). On exposed rocks on hillside. Also known from E Australia, Lord Howe I., and Brazil (Malme 1936; Archer & Elix 1994b; Archer 1997, 2004a; McCarthy 2003c, 2006).
?Pantropical
Illustrations : Archer (1990: 4, fig. 1 – as Pertusaria paeminosa; 1997: 214, fig. 79).
Pertusaria subventosa var. subventosa is characterised by: the saxicolous habit; the sorediate thallus; and the chemistry. It is very rarely found fertile. It resembles the Northern Hemisphere species, P. amara (Ach.) Nyl., but this taxon is mainly corticolous and lacks lichexanthone and β-orcinol depsides such as thamnolic or hypothamnolic acids (Archer & Elix 1994b: 25).
