Lynge B 1930. Lichens from Novaya Zemlya. In Holtedahl O. Report of the Scientific Results of the Norwegian Expedition to Novaya Zemlya 1921. Oslo. 1-299.

It is widely distributed, but it is impossible to say anything of a frequency from these 3 plants.

Thallus circular, diam. commonly 7-10 mm., but then plants coalescing into major quarters, up to 6-7 cm broad, covered.  Crust white, continuous, reticulate-rimose, areolae angular, diam. 0.5-0.8 (-1.0) mm., thin, flat, almost smooth, esorediate, not farinose.  Thallus surrounded by narrow lead-coloured hypothallus.

Apothecia densely conglomerated in central part of thalli, very numerous, nearly confluent, circularly dispersed, sometimes so dense that they seem to form maculae.  Apothecia immersed in almost equal thalline areoles, small: diam. 0.5-1 mm.  Disc black, epruinose, plane or subconcave, margin persistent, whole, moderately thick, often pruinose-surrounded. Excipulum black, hypothecium red or reddish-black.  Upper hymenium 130-140 µ tall, inspersed with beautiful violet-purple or violet-black.  Paraphyses not separate, adding KOH easily separates them, thin, septate, branching towards the apex, slightly thickened.  Eight spores are produced in narrow ascus, but usually a few mature, often appearing sickly, wrinkled.  If developed, spores are hyaline or partly +/- spotted, especially towards the septum or towards the apices; 2-celled and 7 distinct constrictions, 13-21 X 7-10 µ, surrounded by thick halo.

Medulla J, KOH and CaCl₂O₂ no change, hymenium J intense bluish-black, KOH draws out a more intense colour.

Its leading morphological characters are the numerous apothecia, crowded in the centre of the white, continuous thallus.  Only if the areolae are very thin, the leaden-coloured hypothallus is indistinctly visible through the thallus.

The structure of its apothecia obviously refers it to the Rhizocarpon chioneum—expallescens—glacescens tribus.  Rhizocarpon expallescens differs from the other three species by its aeruginose hymenium. –Habitually my species differs much from Rhizocarpon chioneum, which has a very thick farinose thallus with more prominent, scattered, larger apothecia, often there are but a few apothecia in one plant. –I have not seen Rhizocarpon glaucescens TH. FRIES Lich. Scand. II pag. 621, but TH. FRIES writes: “Crusta disperse subsquamulosa verrucosa”, which is quite different from the continous, plane thallus of my species.