Bulletin of the British Museum (Natural History)

LICHEN GENUS MICAREA IN EUROPE 189
when tuberculate. Hymenium 35-45 /xm tall, dilute olivaceous or dilute olive-brown, K+ violet:
pigment confined to gel-matrix. Asci clavate, 30-40x9-5-12 jxm. Spores ± acicular or rodshaped,
curved or ± straight, l-7(-ll)-septate, 14^35(-43)xl-8-2-5(-3) y,m. Paraphyses
numerous, branched, sometimes anastomosing, 0-8-1 /xm wide, sometimes widening to 1-5 /am
towards their apices; apical walls hyaline. Hypothecium 60-100 jxm tall, hyaline, or dilute
olivaceous and then Kf+ violet; hyphae hyaline, 1-2 ^im wide, interwoven or some ± vertically
orientated in the upper part; intermixed with short-celled ascogenous hyphae, c. 2-4 ^im wide.
Excipulum indistinct, evident in sections as a narrow, reflexed, non-amyloid lateral border to
the hymenium, hyaline or pale olivaceous (then K+ violet), varying from paler to darker than
the hymenium; hyphae hyahne, radiating branched and anastomosing, c. 1 /xm wide.
Pycnidia frequent but inconspicuous, immersed within areolae, or emergent to sessile,
whitish to grey-black; walls dull olivaceous (pigment often more intense around the ostioles),
K+ violet. Pycnidia of two types: (a) 60-120 /am diam, immersed, or emergent with gaping
ostioles; conidia {mesoconidia) ± cylindrical to fusiform, 4-5-6xl-2-l-5 /xm; (b) 30-40 /Ltm
diam, immersed to sessile, but ostioles not gaping; conidia (microconidia) short-cylindrical,
3-8-4-8x0-8-l/xm.
Chemistry: Thallus C— , K— , PD— ; sections of thallus and apothecia C- (but olivaceous parts
C-l- violet due to pigment); t.l.c: no substances detected.
Observations: Micarea synotheoides is characterized by its ± acicular or rod-shaped spores,
K-l- violet hymenium, and olivaceous thallus which is j. gelaimous when wet. M. globulosella is
very similar, but differs in having a thallus of whitish or grey, somewhat larger areolae
containing gyrophoric acid. M. nitschkeana differs in the same ways, and in addition has shorter
(rarely over 17 jxm) spores and longer microconidia. M. globulosella and M. synotheoides have
been confused with Bacidia beckhausii (see p. 196) which has similar spores, pigmentation and
paraphyses, but can be distinguished by its large-celled (c. 8-14 fxm diam) phycobiont,
excipulum of coherent (in K) hyphae, smaller conidia (one type only, c. 2-8-3-5X 1-1-4 /xm),
often pruinose apothecia, and usual occurrence on less acidic bark (especially of Acer, Fraxinus,
Populus, and Ulmus), although it does occasionally occur on Quercus trunks and more rarely on
lignum.
Of the four Japanese specimens, two are on bark and two (type material) are on lignum. They
all have rather siiprt spores (14-26 /xm), but appear to agree in most other respects with
collections from Britain and the Atlantic islands. Unfortunately I was unable to find mesoconi-
dia in the Japanese specimens. For the time being, I consider the Japanese and Atlantic
populations as conspecific, especially as the British collections exhibit considerable variation in
spore septation and length. Further collections from Japan are required to finally establish the
relationship between the two populations.
Habitat and distribution: M. synotheoides is an oceanic species mostly found in wooded valleys
on bark or over bryophytes, on the trunks of, for example, Alnus, Betula, Quercus, Larix,
Pinus, and Pseudotsuga, in communities in, or related to, the Parmelion laevigatae alliance.
British collections include the following associated lichens: Bryoria fuscescens, Chrysothrix
candelaris, Cladonia coniocraea, C. squamosa, Haematomma elatinum, Hypogymnia physodes,
Lecanactis abietina, Lecidea icmalea, Micarea alabastrites, M. cinerea, M. peliocarpa, M.
stipitata, Mycoblastus sterilis, Ochrolechia androgyna, Parmelia saxatilis, Pertusaria amara,
Platismatia glauca, Sphaerophorus globosus, Trapelia corticola in ed., and Usnea subftoridana.
The single British collection on lignum {Coppins 2299) was on a rotting trunk of Pinus. In the
Canary Islands it occurs on Erica arborea in a photophobus and hydrophilic community
composed of crustose lichens with Atlantic distributions (Topham & Walker, loc. cit.). In the
Azores it occurs in a more or less identical community on Cryptomeria.
Apart from the type locality in Japan, it is known only from western Britain, the Azores, and
the Canary Islands (Tenerife). It should be sought for in suitable habitats in other oceanic parts
of Europe (e.g. south-west Norway, Bretagne, the Pyrenees, and Portugal).