CRAPHIS ScnIPTA - Universitetet i Oslo

66 Lars Arvidsson and Per-Olof Martinsson
Figure l. The distribution of Caloplaca
obscurella in Sweden.
tion "1164" which might refer to January L864.
Four specimens (H-NYL 29396-97!, S! and
M!) are undated. These specimens are probably
part of the original material and can be
regarded as isotypes.
In Fries (1871 p. I8Z) Lecanora rylitella
(Nylander 1867) is given as a synonym of C.
obscurella. However, the original material (H-
NYL 2L493!) has simple, oblong spores.
Description
Thallus finely areolate or pustulate or uneven
to smooth, sometimes + disappearing. Areolae
usually distinct, round or irregular, plane to
convex, epruiose, discrete at first, becoming *
confluent with og€, 0.2-0.5(-1.0) mm diam.
Areolae rarely minutely lobulate or crenulate,
almost squamulose. Thallus usually greyish
white to grey, occasionally yellowish grey,
greyish green, bluish grey to almost black.
Fresh material of specimens with thick areolae
is greenish when moist.
Soralia usually frequent and prominent,
sometimes scarce, round or irregular, deeply
concave, delimited by a ring of minute cortex
lobes, white or green (fresh material), some-
GRAPHTS SCRTPTA 5 (lee3)
times yellowish or bluish green, 0.1-0.5 mm
diam; starting as a shallow pustule which splits
open to a crater. Soredia leprose or fine
granular, formed at the bottom and on the
internal walls of craters. In old soralia the dispersed
soredia leave characteristic, empty cups.
Apothecia biatorine to lecanorine, often
present (found in 90 Vo of the examined
specimens) and sometimes numerous, scattered,
0.2-0.5(-0.9) mm diam., usually sessile,
sometimes innate when young. Disc plane or
concave when young, usually becoming slightly
convex whith z9e', brown, sometimes pale
brown or yellowish, dark reddish brown or
black. Proper margin I distinct, often becoming
excluded in convex apothecia, usually concolorous
with the disc or slightly paler. proper
margin often surrounded by or occluded by a
greyish white and thick thallus margin.
Spores polarilocular, colourless, (10-)11-
15(-16) x (5-)6-7(-3) pm. Septum usually
thick,
spores.
frcnidida absent.
Thallus and soralia K-, C-, KC-, pdand
UV-.
Variation
The habit of Caloplaca obscurella is quite
variable and can be correlated with ecological
conditions. Specimens growing i open, exposed
habitats usually have a very thin thallus, which
often is reduced to scattered soralia. Under
more humid conditions, e.g. at the base of
alders along streams and lakes, the thallus is
prominent and sometimes slightly lobulate at
the margins (e.9. Viistergotland, G6teborg,
Liirjeholm, 4.1.L990, Arvidsson (LA)). The
thallus of these specimens become fresh green
when moist (e.g. Dalsland, Ftirgelatr&,
17.VII.1988, Martinsson (POM); G6tehrg,
Angered 31.X.1986, 23.IV.Lgg7, Arvidsson
(LA)).
Typical crater-like soralia are always present
but more or less well developed according
to a pattern similar to the rest of the thallus.
Thus, specimens from humid situations with a
prominent thallus also have numerous, well