Mycoglaena
Unlichenized fungi that grow on bark, often as part of crust lichen communities; thallus not apparent; perithecia low-convex or flattish, black; perithecial wall formed of tangled hyphae, dark blue-green, not extending below the hymenium; exciple poorly formed and scarcely apparent; hymenium formed of thin, scarcely branched paraphyses embedded in I- gel; asci narrowly elliptical, IKI-, the apex modestly thickened and lacking an ocular chamber; spores colourless, 8 per ascus, with multiple transverse septae or muriform, ovate, with constrictions at each septum, perispore scarcely developed.
References: Harris 1973; Purvis et al. 1992.
Mycoglaena myricae (Nyl.) R.C. Harris
Thallus immersed, inconspicuous, lacking algae; perithecia black as seen macroscopically, but dark blue-green as seen in LM; spores pointed at both ends, one of the central cells distinctly larger than the others, 18-23 × 6-8 µ.
Reactions: All spot tests negative.
Contents: No lichen substances known.
Habitat: On smooth bark of Betula twigs. Lower elevations.
Similar Species: In our area, no other peritheciate crust has a blue-green perithecial wall, but since this colour is apparent only in LM, this species is easily mistaken macroscopically for a number of other unlichenized peritheciate crusts, especially species of Arthopyrenia.
Local Status: Rare.