Bulletin of the British Museum (Natural History)

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LICHEN GENUS MICAREA IN EUROPE 175 material has not been located in BM but it could be elsewhere (? G). Under the taxonomic arrangement given here Zwackh's epithet is of no consequence. If the chemical races of M. prasina were to be awarded varietal status, then under the provisions of Article 72 the name ' Catillaria prasina p. [var.] byssacea Th. Fr. (1874)' could become important and require typification. If this name was typified with a specimen containing 'prasina unknown A' then it would be the earliest available name at that rank. Thallus effuse and often wide-spreading, very variable in colour, pale fawn (dry shaded situations), light green, pale to dark grey-green (often with glaucous hue), or olivaceous to olive-black, often appearing ± gelatinous when moist, composed of small ± globose granules (goniocysts). Goniocysts c. 12^0(-60) jxm diam, thinly scattered, or vertically proliferating to give the thallus a soft isidiose appearance, or densely aggregated to form a thick granular crust up to 200 />tm deep. Goniocysts ecorticate, often with shortly protruding hyphal filaments; outermost hyphae of superficial goniocysts sometimes surrounded by greenish, K+ violet pigment. Phycobiont micareoid, cells 4-7 ^tm diam. Apothecia usually numerous but sometimes few or absent, immarginate, sometimes adnate and shallow-convex, but more usually becoming markedly convex, subglobose or tuberculate; colour variable, whitish or pallid {'micrococca' shade-forms), pale to dark grey, brownish grey, or grey-black, matt; 0- 1-0-4 mm diam, or to 0-6 mm when tuberculate. Hymenium 28-45(-52) H^va tall, hyaline or dilute dull straw, but more usually dull olivaceous, especially in the upper part (but coloured portion not sharply delimited) or in vertical streaks; pigment K+ violet, HNO3+ red, confined to gel-matrix. Asci clavate or cylindrical-clavate, 26-40(-50)x8-12 /u,m. Spores ovoid-ellipsoid, ovoid, ovoid-oblong or oblong, 0-l(-3)-septate; when 1-septate the lower cell is slightly longer and narrower than the upper, and there is often a slight constriction at the septum; variable in size, in range 8-14(-17)x2-3-4(-5) /xm. Paraphyses rather numerous, branched and anastomozing, 0-5-1 /xm wide; apical parts often wider, to 1-5 /xm, but not thickened by pigment; epithecial pigment confined to surrounding gel matrix. Hypothecium c. 40-170 /xm tall, hyaline to dilute dull yellowish; hyphae interwoven, some becoming vertically orientated towards the hymenium, c. 0-7-1-3 jxm wide; ascogenous hyphae with swollen cells, c. 2-4 /xm wide. Excipulum poorly developed, sometimes evident as a narrow, hyaline or dilute olivaceous-straw (K-l- violet), non-amyloid, reflexed zone; hyphae radiating, branched and anastomosing, c. 0-7-1 /am wide. Pycnidia often present but usually inconspicuous, white, or upper part around the ostiole grey (due to olivaceous, K+ violet pigment), immersed to sessile (never distinctly stalked), of two types: (a) c. 50-120 /xm diam, emergent to sessile, ostiole sometimes gaping; conidia (mesoconi- dia) ± cylindrical or narrowly obpyriform, often biguttulate and slightly constricted near the middle, (3-5-)4-6x 1-2-1-7 /xm; (b) c. 30-60(-100) /xm, usually immersed in surrounding goniocysts, ostiole rarely gaping; conidia (microconidia) cylindrical or narrowly fusiform, (5-)5-5-8x0-7-l/xm. Chemistry: All parts K— , C— (but olivaceous pigment C-l- violet, never red), PD— ; t.l.c: specimens have one of three unknowns ('prasina unknown A', 'B', or 'C; see p. 87); trace amounts of gyrophoric acid sometimes detected, possibly due to contamination by intimately associated species such as Lecidea icmalea and L. granulosa agg. Observations: Micarea prasina is the commonest and most variable member of the genus. However, it is one of the few European species whose thallus is composed of minute discrete granules (goniocysts). Two other species with a similar thallus are: M. hedlundii (q.v.) with a K-l- red oily substance in the goniocysts and conspicuous tomentose, brown, stalked pycnidia; and M. melanobola which has a sharply delimited epithecium (pigment closely adhering to apices of the paraphyses) and shorter microconidia . Both of these species appear to be very rare A comparison of the diagnostic features of M. melanobola, M. prasina and M. misella are given in Table 6. Diminutive forms of M. prasina with small pallid apothecia and a scanty thallus have sometimes been regarded as a distinct species {'Catillaria micrococca') . Such forms have the same basic thallus structure, spores, paraphyses, anamorphs and chemistry (with either 'prasina unknown A' or 'B') as more typical forms (with coloured apothecia and more robust thallus). .
176 BRIAN JOHN COPPINS and I have seen intermediates on many occasions. The 'micrococca' forms are found in heavily shaded situations (e.g. tree trunks in dense conifer plantations, and trunks of understory trees or shrubs) and I consider their diminutive stature and lack of pigmentation to be a phenotypic response to low light intensities. The specimens described as Micarea polytrichi are similarly diminished forms, in this case overgrowing mosses (mainly Polytrichum spp.) by woodland roads. European populations of M. prasina have been found to be represented by three chemical races, each with one of three distinctive, but as yet unidentified, substances (see p. 87). During the course of the present study I have been tempted to recognize the chemical races as formal varieties. However I defer from doing so at this time because: (a) the chemical structure and biogenetic relationships between the three substances is not yet known; (b) the three chemical races do not consistently correlate to any clear differences in morphology; (c) the correlations between chemistry and distribution and (or) ecology are as yet uncertain. In the British Isles (at least) the race containing the 'unknown A' is by far the commonest and is a ubiquitous coloniser of trees and shrubs in all types of woodland (including young conifer plantations), occurring on tree boles, bark and lignum of fallen trees and stumps, and fallen sticks; it also occurs on shaded mossy turf on the ground and amongst rocks (usually with an east- or north-facing aspect) in maritime situations. The race containing 'unknown B' has a more restricted ecology and is mainly found in old woodland situations (including the native pine-woods), growing on the rather dry lignum or old bark of large stumps or fallen trunks; it has not been found on coastal turf or rocks. Specimens of this race tend to have a thick, pale grey (often abrading to greenish Map 18 Micarea prasina sensu lato • 1950 onwards O Before 1950
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20 BRIAN JOHN COPPINS Micarea The g
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22 BRIAN JOHN COPPINS Morphology Th
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24 BRIAN JOHN COPPINS (ii) Goniocys
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26 BRIAN JOHN COPPINS A B Fig. 2 'M
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30 BRIAN JOHN COPPINS Fig. 5 Sketch
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32 BRIAN JOHN COPPINS Fig. 6 Ascus
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34 BRIAN JOHN COPPINS Fig. 8 M. ala
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36 BRIAN JOHN COPPINS Fig. 10 A, M.
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38 BRIAN JOHN COPPINS Fig. 12 A,M.
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40 BRIAN JOHN COPPINS r\ U Fig. 14
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42 BRIAN JOHN COPPINS Fig. 16 M. in
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44 BRIAN JOHN COPPINS Fig. 18 M. le
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46 BRIAN JOHN COPPINS Fig. 20 A-B,
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48 BRIAN JOHN COPPINS Fig. 22 M. me
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52 BRIAN JOHN COPPINS Fig. 26 M. pr
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54 BRIAN JOHN COPPINS VJ Fig. 28 A,
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56 BRIAN JOHN COPPINS Fig. 30 M. su
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58 BRIAN JOHN COPPINS Fig. 31 - con
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60 BRIAN JOHN COPPINS Fig. 33 M. tu
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62 BRIAN JOHN COPPINS Fig. 34 Two t
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64 BRIAN JOHN COPPINS Table 1 Conid
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66 BRIAN JOHN COPPINS Fig. 36 Sugge
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68 BRIAN JOHN COPPINS Fig. 37 M. ad
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72 BRIAN JOHN COPPINS n 1/ [\ f] n
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. 88 BRIAN JOHN COPPINS the epithec
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90 BRIAN JOHN COPPINS fM. elachista
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92 BRIAN JOHN COPPINS Saxicolous ha
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LICHEN GENUS MICAREA IN EUROPE 95 T
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LICHEN GENUS MICAREA IN EUROPE 97 a
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Infrageneric considerations LICHEN
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5. Micarea bauschiana (Korber) V. W
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Page 196 and 197: conferanda (Lecidea) 205 confusula
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