Bulletin of the British Museum (Natural History)

LICHEN GENUS MICAREA IN EUROPE 193
continuing into it as stout, pigmented paraphyses; ascogenous hyphae similarly pigmented, with
swollen cells c. 3-5 fxm wide. Excipulum not evident, even in sections of young apothecia.
Pycnidia often present, ± immersed, black, 60-120 /u,m diam, ostioles often gaping; walls dark
aeruginose, K— , HNO3+ red; conidiogenous cells slender, cylindrical, 5-10x1-1-5 /u,m, often
with a swollen, sometimes pigmented, base up to 3-2 jxm wide, and sometimes with one or two
percurrent proliferations; conidia (mesoconidia) ± cylindrical, sometimes faintly biguttulate,
3-4-3 X 1-1 -4 /xm.
Chemistry: Thallus K— , C— , KC— , PD-; sections of apothecia C—; t.l.c: no substances.
Observations: Micarea tuberculata is characterized by its rather small, markedly convex, often
tuberculate, blackish apothecia, blue-green hymenium, aeruginose-black hypothecium and
small, ovoid-oblong, 0-1-septate spores. The relative proportion of simple to 1-septate spores
can vary greatly between collections, and in some specimens no septate spores can be found. M.
tuberculata has often been confused with forms of M. sylvicola with small, immature spores, but
such spores are always ellipsoid or ovoid-ellipsoid, and quite distinct from the predominantly
oblong-ovoid spores of M. tuberculata. If pycnidia are present the two species can be separated
on the size of their conidia, which are significantly longer (c. 4-6)u,m) in M. sylvicola. M. olivacea
(q.v.) is superficially similar to M. tuberculata, but has slightly larger spores, shorter conidiogenous
cells, and a micareoid phycobiont. Also of similar appearance is Psilolechia clavulifera
(p. 201), but it has smaller spores, a pale hypothecium, numerous, stout, non-pigmented
paraphyses, and a very different phycobiont.
Map 26 Micarea tuberculata • 1950 onwards O Before 1950