Flora of New Zealand Series

Holotype: New Zealand. Campbell I., J.D. Hooker – UPS. Isotype – FH.

Description : Flora (1985: 9).

Chemistry : Cortex and phyllocladia K+ yellow; medulla K−, C−, KC−, Pd+ red (or + yellow); containing atranorin, argopsin, fumarprotocetraric (or psoromic) and perlatolic acids. Lamb (1974: 449–450) notes that populations of A. megalospora contain two distinct chemodemes: one with fumarprotocetraric acid (Pd+ red), and one in which this compound is replaced by psoromic acid (Pd+ yellow). The two chemodemes are morphologically indistinguishable and share the same geographical distribution.

A: (above Musgrave Inlet, Stony Peak, Mt Easton, Mt Eden). C: (Mt Honey, Mt Azimuth, Mt Dumas, Mt Fizeau [see Poppleton 2001: 224]). On exposed rock outcrops in subalpine grassland, open shrubland and in fellfield. Known also from Macquarie I. (McCarthy 2003c) but not recorded from Stewart I., or the mountains of South I.

Endemic

Exsiccati : Vězda (1966a: No. 495 pr.p.).

Illustrations : Fries (1858: pl. VII, fig. 5A); Lamb (1974: 448, fig. 1; 449, fig. 2; 461, pl. 1, figs 1,2); Jahns (1970: pl. 84, figs 1–6).

Argopsis megalospora is scarcely likely to be confused with any other lichen in New Zealand except for Sterecaulon argus (q.v.), and in the Auckland Is and in Campbell I., the two species are sympatric. The plane, expanded apothecial disc, the massive, warted thalline exciple, the plane, smooth pseudopodetial cortex and the scarcity of cephalodia and phyllocladia sufficiently distinguish A. megalospora from S. argus. In addition, the large, muriform ascospores of A. megalospora are characteristic.