Flora of New Zealand Series

≡Lecanora caesiorufella Nyl., Flora 68: 442 (1885).

Description : Thallus pale to dark greyish or not apparent, verrucose to effuse or absent, in narrow patches or lines, 0.5–1(–2) cm wide. Apothecia prominent, sessile, solitary or crowded, rounded or irregularly contorted through mutual pressure, 0.1–0.5(–0.8) mm diam., disc plane to subconvex, matt, cinnabar-red, rust-red to dark ferrugineous reddish brown; thalline exciple not apparent; proper exciple thin, entire, slightly paler than or concolorous with disc, eventually occluded with age. Epithecium yellow brown or brown, densely granular, 8–15 μm thick. Hymenium colourless, without oil droplets, 55–75 μm tall. Asci broadly clavate, 50–60 × 15–20 μm, 8-spored. Ascospores biseriate in ascus, broadly ellipsoidal to oblong-ellipsoidal, 11.5–13.5(–15) × 6.5–8.5 μm; septum 3.5–5 μm thick, c. ⅓ of length of spore.

Chemistry : Thallus K−, apothecia K+ reddish purple; containing parietin

S: Otago (Poolburn Reservoir, Flat Top Hill). On schist outcrops in grassland where it appears to be rather rare, and where it grows closely associated with mosaics of mainly dark-coloured, crustose lichens on steeply inclined to vertical faces (E facing) in full sun, and on the upper edges of dry underhangs. Associating with Candelariella vitellina, Lecanora rupicola, Lecidea fuscoatrula, Ramboldia petraeoides, Rhizocarpon geographicum, R. grande. It is often quite difficult to pick out in these habitats. Still very poorly collected and understood in New Zealand. Known also from Shetland Is, Austria, Sweden, Norway and Svalbard (Magnusson 1944b; Søchting 1989; Santesson 1993; Hafellner & Türk 2001; Coppins & Fletcher 2001b; Santesson et al. 2004).

Bipolar

Illustrations : Søchting (1989: 246, fig. 9; 247, fig. 10).

Caloplaca caesiorufella is characterised by: the saxicolous habit; the grey-white, rather inapparent thallus; prominent, clustered, small, rust-red to reddish-brown apothecia; and oblong, ellipsoidal ascospores with a septum to ⅓ the length of the spore.