Bulletin of the British Museum (Natural History)
Bulletin of the British Museum (Natural History)
Bulletin of the British Museum (Natural History)
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LICHEN GENUS MICAREA IN EUROPE 161<br />
Thallus effuse, endoxylic and visible as a white stain, or epixylic, or rarely epilithic; superficial<br />
thallus formed <strong>of</strong> whitish, greenish-white or grey-white, convex areolae, c. 0-06-0-2 mm diam,<br />
which are especially well developed around <strong>the</strong> apo<strong>the</strong>cia; areolae sometimes coalescing to form<br />
a thickish crust up to 0-2 mm thick, which may eventually become rimose. Areolae in section<br />
without a hyaline amorphous covering layer. Phycobiont micareoid, cells 4-7 /u,m diam.<br />
Apo<strong>the</strong>cia numerous, occasionally coalescing, adnate, convex, soon becoming hemispherical,<br />
but never globose or tuberculate, grey-black, or pallid, reddish brown or brown-grey in shade<br />
forms, 0- 15-0-46 mm diam; disc matt or slightly glossy; immarginate but <strong>the</strong> adnate rim is <strong>of</strong>ten<br />
seen as a ± colourless or watery grey zone, c. 20-40 /xm wide. Hymenium 40-45 /xm, ± hyaUne<br />
with upper part dark olivaceous or grey-green, K— , HNOs-f- purple-red, or ± hyaline<br />
throughout in shade forms. Asci cylindrical-clavate, 38-40x10-12 /xm. Spores simple, <strong>of</strong>ten<br />
biguttulate, ellipsoid, ovoid-ellipsoid or oblong-ellipsoid, 9-12x4-5 /xm. Paraphyses ra<strong>the</strong>r<br />
scanty, branched (especially in <strong>the</strong>ir upper parts), sometimes anastomosing, 1-1-5 /zm wide,<br />
<strong>of</strong>ten sUghtly incrassate at apices to 2 /^m wide; or upper 9-15 /xm <strong>of</strong> paraphyses thickened by<br />
dense greenish pigment and <strong>the</strong>n to 3-5 /xm wide. Hypo<strong>the</strong>cium c. 70-120 ^im tall, dark reddish<br />
brown, K— , HNO3—<br />
; hyphae c. 1-2 /xm wide embedded in <strong>the</strong> densely pigmented matrix,<br />
interwoven but becoming vertically orientated towards <strong>the</strong> hymenium; ascogenous hyphae with<br />
short, swollen cells to 5 (xm wide. Excipulum sometimes evident in sections <strong>of</strong> young apo<strong>the</strong>cia<br />
as a non-amyloid, hyaline zone, but soon reflexed and obscured in older apo<strong>the</strong>cia; composed <strong>of</strong><br />
radiating, branched and anastomosing hyphae l-l-5(-2) ^im wide.<br />
Pycnidia rare, sunken within <strong>the</strong> areolae, c. 40-50 fxm diam; upper part <strong>of</strong> wall around <strong>the</strong><br />
ostiole olivaceous, lower part reddish brown, all parts K-. Conidia {microconidia) cylindrical,<br />
4-6x0-8-1 /xm.<br />
Chemistry: Thallus K— , C— , PD- ; apo<strong>the</strong>cia sections C— ; no substances detected by t.l.c.<br />
Observations: Micarea muhrii is characterized by its convex-adnate, never tuberculate,<br />
usually dark grey apo<strong>the</strong>cia, greenish upper hymenium, dark reddish brown hypo<strong>the</strong>cium<br />
(without green or purple tinges, even in K), and simple spores. It recalls <strong>the</strong> mainly saxicolous<br />
M. lutulata in its pigmentation, but that species differs in having convex-subglobose, <strong>of</strong>ten<br />
tuberculate apo<strong>the</strong>cia, smaller spores, and a larger celled phycobiont. The lignicolous M.<br />
melaeniza is ano<strong>the</strong>r species with similar pigmentation, but has smaller, markedly convex to<br />
tuberculate apo<strong>the</strong>cia, smaller spores, and sessile or stalked pycnidia.<br />
Habitat and distribution: Often in abundance on lignum <strong>of</strong> decorticate logs that lie across<br />
streams and probably become inundated at times; collected once on a periodically inundated<br />
boulder in a stream. So far, known only from Varmland in Sweden, from where it has been<br />
found in at least four localities by Lars-Erik Muhr, in whose honour I have <strong>the</strong> pleasure <strong>of</strong><br />
naming this species.<br />
28. Micarea myriocarpa V. Wirth & Vezda ex Coppins, sp. nov.<br />
(Figs 23C, 47C; Map 14)<br />
Micarea myriocarpa V. Wirth & Vezda in Poelt & Vezda, Bestimmungsschl. europ. Flechten, Erganzungsheft<br />
I: 161 (1977); nom. nudum (Art. 32). - Micarea myriocarpa V. Wirth & Vezda in V. Wirth,<br />
Flechtenfl.: 341, 345 (1980); nom. nudum (Art. 32).<br />
Thallus effusus, farinoso-granulosus, tenuissimus vel crassiusculus ad 0-3 mm crassus, pallide viridis vel<br />
viridulo-fulvus. Algae cellulis ± globisis, c. 4-1 ^tm diam, conglomeratis in granula goniocystiformes.<br />
Apo<strong>the</strong>cia immarginata, primum convexo-hemisphaerica mox tuberculata, pallide vel obscure rufa, vel<br />
fusca, 0-1-0-25 mm diam. Hymenium 25-35 /xm altum, ± hyalinum vel dilute rufo-brunneolum, cum vittis<br />
verticalibus obscure rufo-brunneolis, K — . Ascosporae oblongae vel oblongo-ovoideae, rectae vel ±<br />
curvatae, 5-5-8-5 x 1 •5-2-5 /xm. Paraphyses aliquantum paucae, dimorphae:p.p. hyalinae, laxae, simplices<br />
vel parce ramosae, interdum anastomosantes, graciles, 0-8-1-2 fxm latae, apicibus interdum incrassatis ad<br />
1-8 fim \ahs; p.p. pigmentiferae, fasciculatae, plerumque simplices, crassae, 2-3 /xm latae. Hypo<strong>the</strong>cium<br />
rufo-fuscum vel armeniaco-fuscum, K — , HNO3<br />
- . Excipulum nullum. Pycnidia pauca et inconspicuosa, ±