Flora of New Zealand Series

Description : Thallus effuse, of scattered to mostly confluent areolae sometimes clumping to produce an irregularly warty thallus up to 1 mm thick; prothallus not apparent. Areolae (70–)100–300 (–400) μm diam., convex to ±globose, creamy white to dull-yellowish (isabelline), ecorticate but with a hyaline epinecral layer to 12 μm thick. Photobiont cells micareoid, 4–7 μm diam. Cephalodia absent. Apothecia numerous, (0.2–)0.3–0.6(–0.8) mm diam., or forming tuberculate clusters up to 1.2 mm diam., sessile, adnate or constricted below and sometimes ±turbinate, shallowly convex to hemispherical or ±globose, immarginate, black but sometimes pale at outer edge and sides. Hymenium 53–60 μm high, pale-aeruginose, but with a dark-aeruginose epithecium (K−, N+ red), 4–12 μm thick. Paraphyses numerous, slender, sparingly branched and anastomosing, 1.3–1.7 μm wide, slightly swollen to 2 μm wide at apices, each with individual gelatinous hoods (best seen in K), sometimes collapsing in old apothecia and depositing a layer of pigment on the surface of the apices. Hypothecium 100–200 μm thick, hyaline or pale-aeruginose in upper parts. Exciple well-developed, distinct in section, hyaline or pale-greenish or dull-brown in upper and outermost parts, of radiating hyphae, 1–2 μm wide, readily separating in K. Asci narrowly clavate, 43–55 × 10– 12 μm, in K/I as for M. austroternaria. Ascospores narrowly fusiform and ±lunate, (1–)3-septate, 19–26 × 3.5–4 μm. Pycnidia unknown.

Chemistry : Thallus K−, C+ yellowish (faint), KC+ orange, Pd−, UV+ orange-pink; containing thiophanic acid (major), arthothelin (minor), 4,5,7-trichlorolichexanthone (minor), thuringione (tr.), isoarthothelin (tr.), 4,5-dichlorolichexanthone (tr.) and an unidentified xanthone (minor).

S: Southland (Astronomer's Point, Dusky Sound). St: (Port Pegasus, Fraser Peaks, Deceit Peaks). C: (Mt Lyall). On peat hummocks or plant detritus in subalpine to alpine heaths and herbfields, 600–1800 m. Known also from southern South America and Tasmania (Coppins & Kantvilas 1990; Galloway & Quilhot 1999; McCarthy 2003c, 2006).

Austral

Illustrations : Coppins & Kantvilas (1990: 284, fig. 4); Malcolm & Galloway (1997: 132); Malcolm & Malcolm (2000: 132); Lumbsch et al. (2001: 13).

Micarea isabellina is characterised by: the terricolous habit; the creamy white to dull-yellowish (isabelline), warty, areolate thallus; the black, clustered–tuberculate apothecia; and narrowly fusiform to lunate (1–)3-septate ascospores, 19–26 × 3.5–4 μm.