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Buellia discoënsis Lynge
Family: Caliciaceae
Buellia discoënsis image
Lynge B. 1937. Lichens from West Greenland collected chiefly by Th. M. Fries. Meddelelser Om Gronland. 118: 1-225.

Disko: (verisimiliter) Narssaq, on basaltic rocks, very scarce.

Thallus crustose, uniform, small, diam. c. 8 mm, well-developed, almost thick, areolate, areolae white or whitish-grey, almost shiny, small, 0.2-0.3 mm wide, angular, contiguous, but conspicuous black lines separate hypothallus, subplane, but minute cracks make it slightly rugulose.  Thallus surrounded by narrow, but distinct, hypothallus (0.1 mm).

Apothecia very numerous, minute or moderately-sized, diam. 0.3-0.5 mm, one immersed in each areole, subequal in thallus or then slightly emergent.  Disc naked, black, plane, surrounded by the beginning of the concolourous margin.  Excipulum hyaline, and also with hypotheciumHymenium narrow, 65-75 µ tall, dirty brown or sooty above.  Paraphyses apices dark, clavate-thick, distinctly septate, not conglutinate.  Spores 8, 2-celled, contricted middle, dark, 12-16 X 7-8 (-10) µ, epispore unequally thick.

Hymenium J beautiful blue wine, medulla J intensely blue, KOH soon or temporarily interjected with red (minute crystals, subfarinose).

Its chemical reaction, as well as the internal structure of its apothecium are almost identical with VAINIO’s Melanaspicilia dubia.  Professor SAMUELSSON, Stockholm, has been kind enough to send me his only specimen of VAINIO’s species for comparison.  It differs considerably in its habitus.  Its areoles are very small and thin, though distinctly convex, dispersed, and of a brownish colour.  Its apothecia are more immersed, more aspicilioid than in my species, the fertile areolae are only a thin ring around the apothecia.

After the material I do not venture to unite the two species, but a larger material may bring intermediate stages.  That would only be an advantage, for it is a greater interest to trace the distribution of our plants over such great distances than it is to describe a new species.

The habitus of my species resembles B. Malmei LYNGE (Lich. Bear Isl. 1926, p. 65, and Lich. Nov. Zemlya, 1928, p. 246, pl. IV, fig. 23-24 and XIII, fig. 1), differing in its negative reaction with KOH.  It also resembles B. immersa  LYNGE (Lich. Nov. Zemlya, 1928, p. 246, pl. IV, figs. 18-19, and XIII, fig. 3), differing in its negative reaction with J .  On the whole these Arctic “Melanaspiciliae” are often little different in habitus, separating characters are here to be looked after in their chemical reaction.

It should, however, be stated that in the present plant the reaction with KOH is not always equally intense.  At the first examination I obtained a precipitation of characteristic small grains or short, more cylindrical crystals, but on reexaminating the plant before the preparation of the manuscript I was unable to obtain the precipitation.  Giving preference to the positive find I distinguished the plant from B. Malmei.

Unfortunately we know little, if anything, of the causes of the different chemical substances of the lichens.  Do they always suggest genotypical differences?