Mycoglaena myricae
Thallus: absent or at least inconspicuous; probably not lichenized.
Anamorph: conidiomata pycnidia, 40-60 µm diam., flattened and similar to but smaller than the ascomata. Conidia 4.5-5 (-5.5) × ca 0.8 μm, bacilliform.
Teleomorph: ascomata perithecia, flattened. Involucrellum (clypeus) formed in the outermost compressed layers of the host periderm, 200-300 µm diam., composed of 2-3 layers of branched and anastomosing hyphae ca 4 µm diam., with rather thick blue-green walls, K-, N+ red; often pushed upwards by the developing ascomata and with a grey to silver outer rim. Ascomata 200-250 (-400) µm diam. and 60-70 µm tall, flattened, circular to broadly elliptical in outline, the ostiole inconspicuous. Peridium to 25 µm thick, composed of small globose hyaline cells 2-3 µm diam. Interascal tissue composed of numerous anastomosing pseudoparaphyses ca 1 µm diam. Asci 70-80 x 12-14 µm, cylindrical to narrowly obclavate, the apex rounded, short-stalked, fissitunicate, the apex usually thickened internally but without a distinct ocular chamber, not bluing in iodine, 8-spored. Ascospores arranged biseriately, 15-20 x 4.5-7 µm, fusiform-ellipsoidal to ovoid-fusiform, the ends usually acute, hyaline, 3-septate, the second cell ± enlarged, constricted at the septa, smooth, without a perispore, gelatinous sheath or appendages.
Chemistry: lichen products not detected by TLC.
Assessed by Woods & Coppins (2012) as of Least Concern. Listed as Nationally Scarce, but it is certainly under-recorded.
On living bark of Myrica gale; occasionally on smooth bark of other woody plants including Alnus, Betula and Sorbus.
Mostly in the north and west British Isles. BLS map here.