Flora of New Zealand Series

Holotype: New Zealand. Otago, Flagstaff Hill 700 m, on schist. J.S. Thomson ZA 149, W.

Thallus to 15 mm tall, fertile pseudopodetia conspicuously taller than sterile pseudopodetia. Pseudopodetia simple, occasionally bifurcating at apices, terete, finger-like, corticate, cortex continuous, smooth to cracked, verrucose-wrinkled, whitish-cream never purplish-brown, exposed forms greyish, the result of a crazing of fine black lines across the cortex. Phyllocladia absent. Cephalodia basal, pale yellowish-brown or greenish, never black, distinctly cerebriform, convoluted. Apothecia terminal, often 2-3 per pseudopodetium, disc black, 1-4 mm wide, plane at first with a thin, pale margin, becoming convex and immarginate at maturity, thalline exciple smooth, pale yellowish-brown. Hypothecium colourless or pale yellowish-brown, 100-120 µm tall. Ascospores fusiform, acicular, 6-8(-10)-septate, 48-68 × 5-6 µm. Chemistry: Atranorin and protocetraric acid, ± fumarprotocetraric acid, ± perlatolic acid, ± colensoinic acid, ± anziaic acid.

N: (Ruapehu, Ruahine Ra., Tararua Ra.). S: (Arthur's Pass to Fiordland, Flagstaff Hill, Swampy Hill near Dunedin). St: (Tin Ra, Smith's Lookout). On exposed subalpine to alpine rocks.

Endemic

S. gregarium is most closely related to S. caespitosum but is distinguished from it by the following characters: pseudopodetia are taller and often branched at apices, cortex is matt, wrinkled-verrucose, and greyish-white never purplish-brown, the cephalodia are pale, the apothecia at maturity are convex and immarginate, the hypothecium is pale yellowish-brown or colourless, and the ascospores are 6-10-septate.