[Caliciella arenaria (Hampe ex A. Massal.) Fink, more, Calicium arenarium (Hampe ex A. Massal.) Hampe ex Körb., Calicium citrinum (Leight.) Nyl., Chaenotheca arenaria (Hampe ex A. Massal.) Zwackh, Coniocybe citrina Leight., Coniocybopsis arenaria (Hampe ex A. Massal.) Vain., Cyphelium arenarium Hampe ex A. Massal., Cyphelium citrinum (Leight.) Mudd, Phacotium arenarium (Hampe ex A. Massal.) Trevis., Sphinctrina citrina (Leight.) H. Olivier]
Apothecia: 0.6-1.8(-2.5) mm high stalk: 0.08-0.12 mm in diam., dull black with a coarsely granular surface, aeruginose in water mount, sometimes rather smooth and light grayish brown in very long-stalked apothecia; outer part: covered by groups of dark sclerotized hypahe; inner part: consisting of pale and rather straight, interwoven hyphae; hyphae: distinct capitulum: 0.14-0.28 mm in diam.; ascospore mass: dark brown or greenish black, not higher than width of head, epruinose; paraphyses: soon dissolving, not sclerotized exciple: in section reddish brown, well developed asci: broadly ellipsoid, when mature 9-11 x 5-6 µm ascospores: aeruginose, when mature 1-septate, 6.7-8.2 x 2.3-2.9 µm, distinctly ornamented with spiral ridges Pycnidia: absent Spot tests: exciple, stalk and ascospores K+ yellowish brown, N+ aeruginose. Substrate and ecology: on green algae (Stichococcus or others) or lichens (Psilolencia spp.), parasitic or commen salistic, on rocks, or roots, in shaded and humid localities, often under overhanging siliceous rocks World distribution: northern boreal to temperate zone in Eurasia and North America and also in New Zealand Sonoran distribution: California. Notes: Microcalicium arenarium much resembles M. ahlneri; see notes under that species. See Tibell (1997) for fuller description.