Bulletin of the British Museum (Natural History)

LICHEN GENUS MICAREA IN EUROPE 179
Species associated with M. prasina on the hgnum of fallen trunks and large stumps in the
British Isles include Bryoria fuscescens, Chaenotheca ferruginea, Chaenothecopsis spp., Cladonia
chlorophaea agg., C. macilenta, C. ochrochlora, Hypocenomyce scalaris, Hypogymnia
physodes, Lecanactis abietina, Lecidea aeruginosa, L. icmalea, Micarea adnata, M. melaena,
and Platismatia glauca.
In coastal districts M. prasina is often found on plant debris, soil or moribund bryophytes in
rock crevices or on ledges in sheltered gullies, and sometimes it occurs on the ground growing
over plant debris or old Armeria tussocks, etc. Such habitats are usually sheltered and (or) with a
north- to east-facing aspect. Associated lichens are few, but include Cladonia spp., Lecidea
granulosa, L. icmalea, and Lepraria incana agg. Finds ofM. prasina growing directly on rock are
very rare, but I have seen a few collections made from sandstone rocks in woodlands (from east
Sussex and north-east Yorkshire).
M. prasina is still to be found close to the centres of large conurbations and cities (e.g. Bristol,
Edinburgh, London, and the West Yorkshire conurbation), and its persistence is probably due
more to its ability to avoid, rather than tolerate, the direct effects of air pollutants such as
sulphur dioxide and its derivatives. It naturally favours substrata with a low pH and is able to
grow in very sheltered and shaded situations where more light demanding pollution resistant
species (especially Lecanora conizaeoides) are at a competitive disadvantage.
M. prasina s. ampl. is widely distributed in the British Isles and much of Europe. In
Scandinavia it occurs northwards to at least c. 67°N. It may be rare in districts adjoining the
Mediterranean Sea, but those areas are mostly poorly known lichenologically, and I have seen
one collection from Toscana (northern Italy). M. prasina is present in Macaronesia (Azores and
Canary Islands) and I have seen collections of it from several states in the U.S.A. (Georgia,
Maryland, Massachusetts, Michigan, and Wisconsin). In addition I have seen several collections
from South America and Australisia which come close to M. prasina, but these require more
critical study and will be treated in a later publication.
Exsiccata. Containing 'prasina unknown A': Arnold Lich. Exs. 1122, 1472 (BM ex K, M). Korber Lich
Sel. Germ. 250 (L). Lojka Lich. Univ. 29 (BM ex K, M), 30 (BM ex K). Malme Lich. Suec. 23 (M, S)
Rabenh. Lich. Eur. 676 (BM, BM ex K, M, WRSL). Rasanen Lich. Fenn. 651 (BM, BM ex K, M), 652
(BM, BM ex K). Vezda Lich. Sel. 90 (BM, M), 1467 (BM). Zwackh. Lich. Exs. 593A (H-NYL 21601)
Containing 'prasina unknown B': Arnold Lich. Exs. 280C (BM, GZU, M, WRSL). Cumm. Dec. N. Am
Lich. I. 355 (BM, WIS). Hepp Flecht. Eur. 278 (BM, E, M, WRSL). Lojka Lich. Univ. 31 (BM ex K, M)
Chemistry not tested: Arnold Lich. Exs. 279 (WRSL), 280A (BM, BM ex K, M), 280B (BM ex K, M)
Arnold Lich. Mon. 243 (UPS), 245 (BM ex K, M). Hepp Zur. 224 (BERN). Kutak Lich. Bohem. 310 (O)
Magnusson Lich. Sel. Scand. 134 (BM). Malme Lich. Suec. 24 (M, S). Rabenh. Lich. Eur. 733 (H)
Rasanen Lich. Fenn. 653 (LD). Schaerer Lich. Helv. 196 p.p. (BM ex K, M). Vezda Lich. Sel. 1595 (BM
GZU, M). Zahlbr. Lich. Rar. 175 (BM). Zwackh. Lich. Exs. 416 (UPS), 591A (H-NYL 21598), 591B
(H-NYL 21594, 21599), 592A (UPS), 592B (M, UPS), 592C (UPS), 592D (M, UPS), 592E (UPS), 593B
(H-NYL 21600), 593C (H-NYL 21595), 656 (UPS).
35. Micarea pycnidiophora Coppins & P. James
(Fig. 28: Map 21)
in Lichenologist 11: 153 (1979). Type: England, South Hampshire, New Forest, near Cadnam, Shave
Wood, 45 m, on bark of Fagus, 5 xi 1972, B. J. Coppins & F. Rose (E - holotype!; BM - isotype!).
Thallus corticolous, often overgrowing moribund thaUi of bryophytes and other hchens;
effuse, often wide-spreading, thin, uneven, composed of scattered to confluent areolae arising
from a thin varnish-like prothallus. Areolae flattened to convex-hemispherical, grey-green or
dull green, c. 40-100 ^im diam; in section, without a distinct cortex or hyaline amorphous
covering layer. Phycobiont micareoid, cells 4-7 /^m diam.
Apothecia usually few or absent but sometimes abundant, immarginate, convexhemispherical
to globose, often tuberculate, ivory-white to palUd, translucent when moist,
surface matt, 0- 1-0-3 mm diam. Hymenium 35-50 /xm, hyaUne. Asci clavate, 30-35 x 10-12 /am.
Spores ± straight and vertically aligned in the ascus (never tightly spiralled), shortly acicular.