Microcalicium arenarium (Hampe ex A.Massal.) Tibell
* Account prepared by Dr L. Tibell (Uppsala).
Cyphelium arenarium Hampe ex Massal., Misc. Lich.: 20 (1856).
Growing on either pure crusts of Stichococcus or sometimes on mixed crusts of Stichococcus and a member of Cystococcaceae. In some areas mainly parasitic on Psilolechia lucida (Ach.) M. Choisy. Apothecia very variable in size, 0.6-1.8(-2.5) mm high. Capitulum spherical, 0.14-0.28 mm diam. Mazaedium not protruding more than diam. of apothecia. Paraphyses not sclerotized, dissolving at an early stage. Excipulum in section reddish-brown, with a coarsely granular surface; smooth and pale greyish-brown in very long-stalked apothecia. Outer part of stalk covered by groups of sclerotized hyphae; inner part of stalk of pale and rather straight, interwoven hyphae. Asci when mature, broadly ellipsoid, 9-11 × 5-6 µm. Ascospores when mature 1-septate, 6.7-8.2 × 2.3-2.9 µm, distinctly ornamented with spirally arranged ridges. Chemistry: The aeruginose pigment of the apothecia and spores turns brown in K and reverts to intense green if excess acid is added. The structure of this pigment is not known.
S: Nelson, Canterbury. Rare, known only from a few sites in South I. On lignum of Nothofagus and Griselinia in shaded and rather humid situations, 600-900 m.
Cosmopolitan
In the Northern Hemisphere M. arenarium has a wide distribution occurring in Asia, Europe and North America but seems to be rather rare in all of these areas.
