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Bulletin of the British Museum (Natural History)

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184 BRIAN JOHN COPPINS<br />

45-160 ixm tall, hyaline; hyphae interwoven, some becoming vertically orientated towards <strong>the</strong><br />

hymenium, c. 1-2-1 -8 /xm wide, intermixed with ± inflated, short-celled ascogenous hyphae c.<br />

2-5-5 fjcm wide. Excipulum well developed, 25-45 yam wide, dilute fuscous brown; hyphae<br />

radiating, branched and anastomosing, c. 1-3-1-7 jxm wide.<br />

Pycnidia usually present, immersed within areolae with ostioles visible (x50) as minute pores<br />

surrounded by a thin, <strong>of</strong>ten slightly raised, dark brown rim; in section with a simple circular or<br />

flask-shaped cavity, walls hyaline, or pale brown around <strong>the</strong> ostiole; <strong>of</strong> two types: (a) c. 80-200<br />

/xm diam; conidiogenous cells ampulliform to subcylindrical, some with 1-2 percurrent proliferations,<br />

4-10 X 1-5-2-5 /xm, sometimes with swollen base to 4 /xm wide; conida (macroconidia)<br />

helicoid with 2-3 spirals, <strong>of</strong>ten appearing 3-5-septate, overall size 7-10x5-6 /xm, filaments<br />

1-8-2 /xm wide (b) c. 40-100 /xm diam; conidiogenous cells ± cylindrical or ampulliform,<br />

4-lOx 1-1 -4 /xm, sometimes with swollen base to 3 /xm wide; conidia {microconidid) cylindrical,<br />

4-6-6x0-8-1 /xm.<br />

Chemistry: Thallus K— , C-, PD — ; sections <strong>of</strong> apo<strong>the</strong>cia C-; t.l.c: no substances.<br />

Observations: Micarea subnigrata is characterized by its dark grey-brown, verrucose-areolate<br />

thallus, dark brown apo<strong>the</strong>cia, fuscous brown epi<strong>the</strong>cium and excipulum, colourless hypo<strong>the</strong>cium,<br />

and 0-1-septate, eUipsoid spores. However, its most outstanding and characteristic<br />

feature is <strong>the</strong> helicoid shape <strong>of</strong> its macroconidia (Fig. 50A); such conidia are unique in <strong>the</strong> genus<br />

and apparently so in all pycnidial fungi, whe<strong>the</strong>r lichenized or not. In general appearance,<br />

habitat and shape and septation <strong>of</strong> spores M. subnigrata could be confused with M. intrusa, but<br />

Map 22 Micarea intrusa A 1950 onwards A Before 1950 + Micarea subnigrata • 1950 onwards O Before<br />

1950<br />

i

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