Flora of New Zealand Series

P. rufovirescens (Church. Bab.) D. Galloway, Mycotaxon 16: 205 (1982).

Sticta richardii var. rufovirescens Church. Bab., Fl. N.Z. 2: 278 (1855).

Lectotype: New Zealand. Canterbury, Akaroa. ?Hombron, BM ex PC!

Thallus spreading, often entangled, in very large clones, loosely attached, 7-10(-30) cm diam. Lobes linear-elongate, 5-8(-15) mm wide, 5-10(-15) cm long, ± dichotomously branching, contiguous or discrete, rarely imbricate, margins entire, smoothly rounded, without pseudocyphellae, slightly thickened below, apices rounded to truncate or shallowly furcate, rather variable, thinner and elongate to wider and ± imbricate. Upper surface bright lettuce-green when wet, pale greyish-green when dry, smooth, matt, shallowly faveolate, dividing ridges smoothly rounded, undulate, without isidia, phyllidia, soredia or pseudocyphellae. Medulla white. Photobiont green. Lower surface white to pale pinkish-white at margins, darker centrally, wrinkled-bullate especially at margins, glabrous at and towards apices, short, white, delicate, silky-tomentose in older parts, tomentum often sparse or absent. Pseudocyphellae white, punctiform, immarginate, fleck-like at margins, to 0.5 mm diam., centrally, and there with a fine margin, scattered, ± flat or only very slightly verruciform, often clustered. Apothecia marginal, 1-5 mm diam., sessile or subpedicellate, disc pale brownish-pink to red-brown, concave at first, becoming ± plane or undulate, glossy, epruinose, smooth, margins pale buff or pinkish, thin, crenulate, thalline exciple pinkish, corrugate-scabrid. Ascospores mainly 1-, rarely to 3-septate, colourless, fusiform-ellipsoid, (20-)24-27(-32) × (7-)8-9(-11) µm. Chemistry: 7β-acetoxyhopane-22-ol, hopane-15α,22-diol, hopane-7β,22-diol (±). (Wilkins and James loc. cit., Code A).

N: S: St: A: Throughout, common and widespread, s.l. to 1000 m. Mainly a lowland species; it reaches a great size in humid habitats in partial shade. In full sunlight specimens are often suffused brownish. It is most common in podocarp forests or forest remnants, along streams and in altered sites where Leptospermum is an important successional element.

Endemic

P. rufovirescens is a commonly collected, conspicuous endemic epiphyte characterised by a green photobiont, white medulla, a pale lower surface (with only a sparse pale tomentum or tomentum absent altogether), white, punctate pseudocyphellae, rather narrow, dichotomously branching, shallowly faveolate lobes and pale red-brown or pinkish-brown marginal apothecia which are never pruinose. It is distinguished from P. billardieri by the pale red-brown apothecia, colourless spores, pale ± glabrous lower surface, flat, fleck-like pseudocyphellae and a different chemistry. The same characters serve also to distinguish it from P. faveolata which is much more variable in lobe morphology.

In an earlier account this species was referred to P. billardieri [Galloway and James loc. cit., p. 293 (1980)], following an interpretation of billardieri in vogue since the late 19th century. However, rediscovery of La Billardière's type material disclosed the error of this view (see under P. billardieri.) An excellent coloured engraving of P. rufovirescens was given by Richard [ Voy. Astrolabe Bot. Atlas: tab. 9, fig. 1 (1833)] as well as a description of the species as Sticta carpoloma Richard non Delise, in which attention was drawn to the fact that white and not yellow pseudocyphellae were present on the lower surface. At that time the colour of the pseudocyphellae was thought to be of little taxonomic significance, a view not valid today. Montagne [ Annls Sci. nat. Bot. sér. 2, 4: 89 (1835); Voy. Pôle sud...Bot. 1: 187 (1845)] recognised Richard's circumscription of S. carpoloma as a reference to a new species differing from P. carpoloma sens. str.  He described Sticta richardii Mont., based, however, on Juan Fernandez and not on New Zealand material, although in his 1845 paper he refers all New Zealand material (including the type of P. rufovirescens) to S. richardii. Juan Fernandez material differs chemically from New Zealand plants and appears to be an independent taxon. Babington's variety rufovirescens is the earliest available name with typifiable specimens in BM, and has therefore been used for this characteristic, widespread endemic lichen.

P. rufovirescens is illustrated in a monochrome photograph by Martin and Child ( loc. cit., p. 136, pl. 41) as P. fossulata, an illegitimate name based on the nomen nudum Sticta fossulata Dufour, which is, in any case, a synonym of P. faveolata, and by Moore and Irwin ["The Oxford book of New Zealand plants", p. 15, fig. 1 a-d (1978)] in colour, as P. billardieri. The characteristic, two-hopane chemistry was deduced by Corbett and Young [ J. chem. Soc. Lond.: 1556-1563; 1564-1567 (1966)].

P. rufovirescens forms photosymbiodemes with P. murrayi but as an independent species it is distinguished from P. murrayi by the green photobiont, the ± glabrous lower surface and the red-brown or pinkish-brown apothecial discs.