Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Pseudothecia: globose, 130-220 µm diam. ascomatal wall: hyaline in its lower half, greenish or ± brownish blue around the ostiole, basally 10-15 µm thick paraphysoids: abundant, 1-1.5 µm thick asci: 50-70 x 9-13 µm, cylindrical-clavate, mostly 8-spored, rarely 4- or 6-spored ascospores: hyaline, (0-)1(-3)-septate, oval-ellipsoid to slightly fusiform, (14-)15-19(-22) x (4.5-)5-6(-7) µm, with both cells similar in size and a centered septum, but slightly heteropolar, with the lower cell slightly narrower than the upper one Pycnidia: globose, 100-130 µm wide conidia: hyaline, simple, bacilliform, 3-4(-5) x 0.5-1 µm. Hosts: parasymbiotic on Lecanora polytropa, L. intricata and other taxa of this group dwelling in northern territories and in high mountains World distribution: montane and alpine regions of the Northern Hemisphere, profusely cited in Europe and North America Sonoran distribution: Arizona Notes: Cercidospora epipolytropa is specific to different taxa of the Lecanora polytropa group, and is characterized by having ascospores varying from oval-ellipsoid to fusiform, mostly not over 20 µm long. This size is coincident with the values given by other authors on the same hosts (Hafellner 1987b, Vainio 1921). Beside of the size of the ascospores, there are a number of constant differences amongst the studied specimens of C. epipolytropa. The most striking one is the prevailing number of ascospores per ascus, 4 or 8; this difference seems to be associated with variations in the size of asci and ascomata, and also with host characteristics. 8-spored specimens mainly grow on typical Lecanora polytropa from relatively high altitudes localities. On the contrary, the samples of Cercidospora with 4-spored asci come normally from localities at lower altitudes, and grow mostly on a taxon of the