Flora of New Zealand Series

≡Rimelia austrocetrata (Elix & J.Johnst.) Hale & A.Fletcher, Bryologist 93 (1): 26 (1990).

Holotype: New Zealand. Taranaki, New Plymouth, Burgess Park, 7.v.1980, J.A. Elix 4645 – CHR. Isotype – CBG.

Description : Thallus loosely attached, pale green-grey to mineral-grey, 6–12 cm diam. Lobes rounded, imbricate or not, 10–20 (–30) mm wide, apices often laciniate, the laciniae flat or convex, 0.5–1.5 mm diam., 1–5(–8) mm long, moderately ciliate, cilia 0.2–1(–1.5) mm long, simple or sparingly branched. Upper surface white-reticulate at first (×10 lens) but becoming markedly cracked to the margins, developing closed, raised dactyls, dactyls ±curved, laminal, ultimately becoming fused with the formation of laminal ridges, older parts of thallus eventually becoming areolate, the areolae flaking off and exposing the white medulla in eroded areas; without isidia or soredia. Lower surface black, with a naked, brown, marginal zone 1–2 mm wide; moderately to densely rhizinate, rhizines simple or sparsely branched, slender, black. Apothecia rare, pedicellate, to 10 mm diam., disc perforate, pale-tan, concave at first then concave–distorted, margins eciliate, thin, stellate-cracked. Ascospores colourless, ellipsoidal, 12–16 × 8–9 μm. Pycnidia scattered, punctiform, black. Conidia filiform, 9–16 × 1 μm.

Chemistry : Cortex K+ yellow; medulla K+ yellow→red, C− KC+ red, Pd+ red-orange; containing atranorin, chloroatranorin, salazinic acid (major), consalazinic acid (minor) and ±protocetraric acid (tr.).

N: Northland (Whangarei, Kawau I.), South Auckland (Kauaeranga River Coromandel Peninsula, Waihi Beach, Ohope Beach), Gisborne: (Hicks Bay, East Cape), Taranaki (New Plymouth). On trees and shrubs (twigs) in northern, coastal forest and on coastal rocks. Known also from Papua New Guinea, the Philippines, Australia, New Caledonia, Norfolk I. and Lord Howe I. (Hale & Fletcher 1990; Elix 1994r; Louwhoff & Elix 1999, 2000, 2002b; Elix & Schumm 2001; McCarthy 2003c, 2006).

Palaeotropical

Illustrations : Elix & Johnston (1988a: 499, fig. 5); Elix (1994r: 185, fig. 59D).

Parmotrema austrocetratum is characterised by: the corticolous/saxicolous habit; the development of laminal dactyls, the upper surface becoming deeply areolate, the areolae ultimately flaking off and exposing the white medulla. It is distinguished from the related P. cetratum by the development of laminal dactyls, in being rarely fertile, more loosely adnate, and by having a distinct, naked brown, marginal zone on the underside of the lobes (Elix & Johnston 1988a: 496).