Bulletin of the British Museum (Natural History)

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Infrageneric considerations LICHEN GENUS MICAREA IN EUROPE 99 I have given much thought to the possibihty of subdividing the genus Micarea into subgenera or sections. The genus includes several small groups of closely related species, but the affinities of many individual species are difficult to ascertain. I believe that a formal infrageneric classification (above the rank of species) based on current information would be unhkely to withstand the tests of time and serve httle useful purpose. However, that is not to say that such a classification will never be possible. The present study is mainly confined to the 45 European species of Micarea, but the genus is well represented in other parts of the world by some of the same, plus numerous additional species. With such considerations in mind I estimate that the genus, as currently circumscribed, contains about 100 species world-wide. A better understanding of extra-European species may increase the feasibility of subdividing Micarea. Some examples of small groups of apparently closely related species are given below. Within each group all the species have basically similar apothecial construction. For example. Group C all have medium to large sized apothecia, a ± well-developed excipulum, and numerous paraphyses which are of medium thickness and are richly branched (especially in the upper hymenium). Some supplementary common features and other notes are provided for each group - but for more detailed discussions see the taxonomic accounts of the relevant species. Phycobiont is 'micareoid' unless otherwise stated. See under 'Chemistry' for explanation of pigments. Abbreviations: AL, hyaUne amorphous covering layer; Exc, excipulum; Hym., hymenium; Hyp., hypothecium; Th., thallus; Pyc, pycnidia. A. M. lignaria - M. ternaria Th. areolate-type with AL. Th., Hym. and Pyc. with pigment A; Hyp. with dilute pigment A plus dilute dull brown pigment. Spores ± fusiform, 3- or more septate. Mesoconidial states very similar; M. lignaria also has micro- and macroconidial states. Chemistry: argopsin or xanthones (M. lignaria) or no substances {M. ternaria). B. M. leprosula-M. subleprosula Th. sorediate-type. Th. and Hym. with pigment A; Hyp. often with dilute dull brown pigment. Spores ± fusiform, 3- or more septate. Anamorphs unknown. Chemistry: argopsin -I- gyrophoric acid (M. leprosula) or alectorialic acid -I- accessory substances (M. subleprosula). Many affinities with Groups A and C. C. M. peliocarpa - M. alabastrites - M. cinerea Th. areolate-type with AL. Hym. , Th. and Pyc. of M. peliocarpa and M. cinerea with pigment A; all parts of M. alabastrites devoid of pigment. Spores ± fusiform, 3- or more septate. All with microconidia and curved or filiform macroconidia; mesoconidia unknown. Chemistry: all with gyrophoric acid. With Atlantic or sub-Atlantic distributions. Some affinities with Groups A, B, and D. D. M. denigrata - M. nitschkeana - M. globulosella Th. areolate-type but with no AL. Hym., Th. and Pyc. with pigment D; Hyp. hyaline. All with similar micro- and mesoconidial states; M. denigrata and M. nitschkeana also with ± identical macroconidial states. Chemistry: all with gyrophoric acid. Mainly corticolous or lignicolous. These three species appear to show a good example of an evolutionary progression: they are morphologi- cally and chemically ± identical except for the length and septation of spores. E. M. pycnidiophora - M. stipitata Th. areolate-type, but with no AL. Without pigments. Spores ± acicular, 3-7-septate. Pyc. stalked, with mesoconidia; micro- and macroconidia unknown. Chemistry: gyrophoric acid (Af. pycnidiophora) or no substances (M. stipitata). Corticolous and with eu-Atlantic distributions. F. M. elachista - M. rhabdogena Th. areolate-type with cortex and AL (M. elachista) or endoxylic (M. rhabdogena). Upper Hym. with pigment E; Pyc. with pigment D; Hyp. hyaline. Macroconidia unknown. Chemistry: no substances. Mainly lignicolous with boreal or boreal-continental distribution. G. M. botryoides-M. melaeniza Th. weakly areolate (with no AL) or with goniocysts (Af. botryoides) , or endoxylic {M. melaeniza). Hym. and Pyc. walls with pigment A; Hyp. and Pyc. stalks with pigment F. Paraphyses dimorphic. Pyc. stalked with mesoconidia; micro- and macroconidia unknown. Chemistry: no substances. This
100 BRIAN JOHN COPPINS group could possibly be extended to include M. anterior, and there are probably some affinities to species of Groups H and I. H. M. contexta - M. eximia - M. nigella - M. olivacea Th. endoxylic, or forming a thin crust, or weakly areolate. Pigments A and (or) B in various locations. Spores simple or 1-septate. Paraphyses dimorphic. Pyc. black, immersed to sessile, or stalked (A/, nigella). Macroconidia unknown. Chemistry: no substances. Mainly lignicolous and confined (?) to north-west Europe. Probably close to Group G. M. melaena may belong here but has: rather large apothecia, pigment C (usually present in hypothecium), an often well-developed, areolate thallus containing gyrophoric acid, and an ability to produce macroconidia; it may provide a link between Group H and Groups A-D. I. M. bauschiana - M. sylvicola - M. tuberculata - M. lutulata Th. weakly areolate, ± smooth or scurfy. Phycobiont non-micareoid. Pigmentation variable, involving pigments A, B, C, and F; pigment D never present. Spores small, simple, or p.p. 1-septate (M. tuberculata). Paraphyses dimorphic. Pyc. ± immersed. Macroconidia unknown. Chemistry: no substances. Mainly found in dry underhangs in the Micareetum sylvicolae. This group is almost worthy of subgeneric status but it shows some affinities to Group G, and other species, such as M. lithinella. J. M. assimilata - M. incrassata - M. subviolascens - M. melaenida - M. crassipes Th. areolate-type, sometimes with AL. Pigmentation variable, involving pigments A, B, C, D, and E; Hyp. always dark-coloured. Spores rather large, mostly ellipsoid or oblong-elhpsoid and simple or 1-septate. Paraphyses rather stout and sparingly branched. Cephalodia found in first three species. Pyc. immersed. Macroconidia unknown. Chemistry: no substances. Mainly terricolous or muscicolous (never corticolous or lignicolous), and with a ± arctic or arctic-alpine distribution (except M. melaenida). M. crassipes is rather anomalous here because of its very well-developed excipulum and turbinate or stipitate apothecia. K. M. prasina - M. hedlundii - 'Lecidea' levicula [from Cuba] Th. goniocyst-type. Hym., Pyc. and Th. often with pigment D; Hyp. hyaUne; one species (M hedlundii) with pigment H. Spores mostly simple or 1-septate. Pyc. immersed to sessile, or stalked and tomentose {M. hedlundii). Micro- and (or) mesoconidia produced; macroconidia unknown. Chemistry: variable, including 'prasina unknowns' and gyrophoric acid. M. misella and M. melanobola have some affinities to this group, but also with Group D. M. synotheoides may belong near here. Keys to species Guide to keys and identifications Two keys are provided, the first to specimens with apothecia, the second to specimens without apothecia (although often with pycnidia). The keys are for European species, but all those known to me from cool-temperate, boreal, and arctic regions of North America are, by chance, included. The nature of pigmentation and colour reactions observed in anatomical sections is important for the identification of Micarea species. Many of the subtle yet significant colour hues and reactions are obscured by the yellowish illumination given by most bulbs, and it is recommended that a microscope be fitted with a 'daylight' bulb or a blue filter. The preceding sections on 'Morphology' and 'Chemistry' should be read before attempting to use the keys. Particular care should be taken in determining C reactions with apothecial sections. The straw to dull olivaceous, K+ violet pigment found, for example, in M. prasina, M. synotheoides, M. denigrata, and M. nitschkeana, also reacts C+ violet (persistent); this reaction tends to mask the C+ orange-red (quickly fading) reaction due to gyrophoric acid and usually obtainable in the last two, aforementioned species. However, the C+ violet reaction is mostly confined to the upper part of the hymenium, whereas the C+ orange-red reaction occurs in all parts of the apothecium. To carry out the C test cut a hand section of an apothecium and mount in a drop of water near the edge of the cover-slip; lay a piece of tissue-paper over the cover slip to take up any excess water; place the slide preparation on the microscope stage and focus at about x 100 to x200 and note any pigmentation; then, apply a drop of C by the edge of the cover-slip nearest
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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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LICHEN GENUS MICAREA IN EUROPE Tabl
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32. Micarea osloensis (Th. Fr.) Hed
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34. Micarea prasina Fr. LICHEN GENU
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conferanda (Lecidea) 205 confusula
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populina (Lecidea, Micarea) 31,32 p
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