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Bulletin of the British Museum (Natural History)

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164 BRIAN JOHN COPPINS<br />

sometimes evident in young apo<strong>the</strong>cia as a dark (concolorous with hypo<strong>the</strong>cium) narrow zone<br />

forming an edge to <strong>the</strong> reflexed part <strong>of</strong> <strong>the</strong> hymenium; hyphae radiating, branched and<br />

anastomosing, c. 0-8-1 -5 /xm wide.<br />

Pycnidia numerous, black, sessile or more usually stalked, 60-300 jxm tall (including stalk)<br />

and 40-80 jxm diam; stalks (pycnidiophores) simple or sometimes branched bearing up to 4<br />

pycnidia; stalk and pycnidial wall tissues dark purplish brown, K+ dark green, HNO3+<br />

purple-red. Conidiogenous cells A-A-1-6 /xm tall, with a cylindrical neck 1 •9-3-7 fxm tall and<br />

0-8-1-4 fxm wide, and with a swollen base 2-4-3(-3-7) /xm wide, <strong>the</strong> wall <strong>of</strong> which is <strong>of</strong>ten<br />

pigmented; percurrent proliferations not seen. Conidia (mesoconidia) ellipsoid or short cylin-<br />

drical, sometimes faintly biguttulate, 3-4-4-3x1-2-1-6 /xm.<br />

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

Observations: Micarea nigella belongs to <strong>the</strong> group <strong>of</strong> lignicolous species (including M.<br />

contexta, M. eximia, M. melaeniza, M. misella, M. olivacea, and M. rhabdogena) with an<br />

endoxylic or indistinct thallus and small, ± globose to tuberculate, black apo<strong>the</strong>cia. It is<br />

characterized by <strong>the</strong> purple-brown, K-h green pigment in <strong>the</strong> hymenium, hypo<strong>the</strong>cium and<br />

pycnidial tissues, simple spores and stalked pycnidia. It is most likely to be confused in <strong>the</strong> field<br />

with o<strong>the</strong>r species with stalked, black pycnidia, namely M. melaeniza and M. misella. M.<br />

melaeniza differs in having a bright green hymenium, a red-brown hypo<strong>the</strong>cium that does not<br />

turn green in K, a different pycnidial pigmentation and shorter mesoconidia. M. misella has a<br />

K-l- violet hymenium, a ± hyaline hypo<strong>the</strong>cium and an olivaceous, K+ violet pigment in <strong>the</strong><br />

pycnidial wall tissues. Apart from <strong>the</strong>ir lack <strong>of</strong> stalked pycnidia, M. contexta, M. eximia, and M.<br />

Map 15 Micarea nigella # -I-<br />

Micarea olivacea ®<br />

J

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