Caloplaca tornoënsis
Description : Thallus 0.5–1.5 cm diam., greyish white or fawnish grey, granular-papillate to somewhat indistinct, on ±moribund Andreaea. Apothecia scattered to crowded, rounded, 0.1–0.5(–0.8) mm diam., disc orange-brown, plane to subconvex, surface matt to minutely granular; margins persistent, thin, black, to grey-black, glossy. Epithecium dense, orange-brown or yellow-brown, granular (10–)12.5–15(–20) μm thick. Hymenium colourless, 70–80(–85) μm tall. Hypothecium opaque, pale yellow-brown, 25–37.5 μm thick. Asci cylindrical, 50–55 × 15–17.5 μm. Ascospores 1-septate, (15–)17.5–20(–22.5) × 7.5–9 μm; septum to 2.5 μm thick.
S: Otago (Old Man Ra.). Parasitising small clumps of the moss Andreaea on small schist rocks at base of large schist tors, in very exposed, wind-excavated hollows free of snow and subject to extreme freeze-thaw episodes. Associating with: Aspicilia, Bartlettiella fragilis, Caloplaca cinnamomea, Cetrariella delisei, Lecidea fuscoatrula, Ochrolechia xanthostoma, Pertusaria dactylina, Rhizocarpon etc. It is known from Scandinavia, Svalbard, Greenland, Siberia, Europe and North America (Magnusson 1944a; Poelt 1969, 1986; Hansen et al. 1987a; Søchting 1992b; Søchting et al. 1992; Santesson 1993; Esslinger & Egan 1995; Søchting & Olech 1995; Thomson 1997). A related species, also parasitic on Andreaea, C. siphonospora, is known from King George I. and Livingston I. in Antarctica (Olech & Søchting 1993; Øvstedal & Lewis Smith 2001), but it has ±simple ascospores reminiscent of, but smaller than those, in C. nivalis.
Bipolar
Illustrations : Hansen et al. (1987a: 47, fig. 7); Thomson (1997: 176).
C. tornoënsis is characterised by: the muscicolous habit; the indeterminate, spreading thallus parasitising colonies of Andreaea; the small, scattered, orange-brown apothecia with thin, shining grey-black to black margins; 1-septate ascospores, (15–)17.5–20(–22.5) × 7.5–9 μm. C. tornoënsis is virtually impossible to separate from C. nivalis on external characters, but there are very distinct ascospore characters separating these two species (Søchting 1992b).
