Calicium trabinellum (Ach.) Ach.

   Thallus crustose often absent or inconspicuous, otherwise dirty whitish, pale greyish; Apothecia in small globular cups 0.5-1 mm in diameter at the top of a black stalks, 0.5-1 mm high, black, covered, especially on their lower part with a "fluorescent" green-yellow pruina. Asci included in a brown-blackish mazedium, long cylindrical, 40-55 x 5-8 µm according to our measurements, with 8 spores arranged in line. Spores elliptical, once septate with a globule in each cell, brown at the end, surface fissured to cracked, 13-16 x 5-7 µm according to literature; 11-15 x 4-7 µm according to our measurements. Photobiont: Trebouxia. C-, K-, KC-, P-. Mountain species coming on more or less rotten wood of conifers. Cf. Calicium adspersum with brown stalks, with a thallus K + yellow then red, P + yellow to red, clavate asci with spores arranged in a spiral which occurs especially on leafy trees and Calicium glaucellum powdered with whitish.