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Bulletin of the British Museum (Natural History)

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LICHEN GENUS MICAREA IN EUROPE<br />

Table 7 Diagnostic features for <strong>the</strong> separation <strong>of</strong> Micarea denigrata and M. misella.<br />

Apo<strong>the</strong>cia size (mm)<br />

Thallus type<br />

Spore septation<br />

Spore length (/u.m)<br />

Paraphyses<br />

Hymenium<br />

Macroconidia (/u,m)<br />

Mesoconidia (/Am)<br />

Microconidia (/u,m)<br />

Pycnidia (meso-)<br />

Chemistry (t.l.c.)<br />

0-1-0-3<br />

Usually endoxylic; sometimes<br />

with areolae, 60-120 /x,m diam<br />

0(-l)<br />

6-5-9-5<br />

sparse; 0-5-0-8 )u,m wide<br />

C+ violet; very rarely also<br />

C+ orange-red<br />

unknown<br />

3-5-5 X 1-1-5<br />

3-8-5x0-6-0-8<br />

sessile to stalked<br />

nil; but gyrophoric acid<br />

sometimes present in trace<br />

amounts, rarely in large amounts<br />

misella denigrata<br />

0-1-0-5<br />

usually with areolae, 60-200 /nm<br />

diam; rarely endoxylic<br />

(0-)l<br />

(7-)9-16(-18)<br />

numerous; 1-1-7 jxm wide<br />

C+ violet; usually also<br />

C-l- orange-red<br />

12-24x1; curved<br />

2-8-4-5(-5)x 1-2-1-8<br />

(4-5-)5-7-5x 0-7-0-8<br />

immersed to emergent, never<br />

stalked<br />

gyrophoric acid usually present<br />

in large amounts; very rarely<br />

not detectable<br />

and no stalked pycnidia it can be difficult to separate from M. denigrata, especially if in <strong>the</strong> latter<br />

no conidial (or only <strong>the</strong> microconidial) state can be found. In such instances M. misella can<br />

usually be distinguished by its small apo<strong>the</strong>cia, mainly simple, uncurved ascospores and sparse,<br />

thin paraphyses. The same criteria can separate forms <strong>of</strong> both species with an endoxylic thallus<br />

and lacking diagnostic macroconidial or mesoconidial states. A C+ orange-red reaction can<br />

usually be obtained in sections <strong>of</strong> <strong>the</strong> apo<strong>the</strong>cia <strong>of</strong> M. denigrata, although <strong>the</strong> reaction is<br />

sometimes very weak or unobtainable in diminutive, lignicolous, epixylic forms; in M. misella I<br />

have obtained this reaction in only one or two extremely well-developed specimens. Table 7<br />

outlines <strong>the</strong> main diagnostic features <strong>of</strong> <strong>the</strong>se two species. Apart from M. misella, black, stalked<br />

pycnidia are also a characteristic feature <strong>of</strong> M. botryoides, M. melaeniza, and M. nigella;<br />

however, <strong>the</strong> pycnidial wall tissue in <strong>the</strong>se species is brownish or greenish in KOH, and never<br />

violaceous as in M. misella.<br />

For differences from M. melanobola and M. prasina see Table 6.<br />

Habitat and distribution: M. misella is almost exclusively lignicolous (especially on conifer<br />

lignum). It has not been found on bark, but has been collected on Picea cones, old basidiomes <strong>of</strong><br />

polypores (Daedaleopsis confragosa and Gloeophyllum sepiarum), and on moribund Polytrichum<br />

spp. by woodland tracks. Most <strong>British</strong> collections <strong>of</strong> M. misella have been made from<br />

<strong>the</strong> sides and undersides <strong>of</strong> fallen decorticated trunks <strong>of</strong> Pinus, and associated species included<br />

Lecidea icmalea, Micarea prasina, Xylographa abietina, X. vitiligo, Cladonia spp. (scattered<br />

squamules), and Hypogymnia physodes. Reports on exposed roots and stones (e.g. Watson,<br />

1930: 53) refer to o<strong>the</strong>r species, especially M. bauschiana. In Britain M. misella appears to be<br />

ra<strong>the</strong>r rare and restricted to Scotland where it is mainly found in <strong>the</strong> native pine-woods. It has<br />

been reported (as 'Lecidea asserculorum') from England and Wales, but all <strong>the</strong> pertinent<br />

material seen belongs to diminutive forms <strong>of</strong> M. denigrata and M. prasina, or quite different<br />

species such as M. melaena and Cliostomum grifftthii.<br />

M. misella is widely distributed in Europe, especially in areas with naturally occurring<br />

coniferous forests. It is found as far north as Lycksele Lappmark and Norbotten in Sweden, and<br />

an outlying sou<strong>the</strong>rly locality is on <strong>the</strong> Mediterranean island <strong>of</strong> Corsica where it was collected on<br />

<strong>the</strong> rotting lignum <strong>of</strong> Eucalyptus. From outside Europe I have seen material <strong>of</strong> M. misella from<br />

Canada (Ontario and Newfoundland), and from <strong>the</strong> highlands <strong>of</strong> Minas Geraes (at 1400 m) in<br />

Brazil.<br />

Exsiccata: Arnold Lich. Exs. 626, 627 (BM ex K, M). Arnold Lich. Mon. Ill, 241, 307 (BM ex K, M,<br />

MANCH). Britz. Lich. Exs. 208 (M). Claudel «& Harm. Lich. Gall. 445 (BM). Crombie Lich. Brit. 11<br />

A<br />

159

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