Lichen determination keys - neotropical genera -

Identification key and literature guide
to the genera of Lichenized Fungi (Lichens) in the Neotropics
PROVISIONAL VERSION

by H. Sipman, Botanic Garden & Botanical Museum Berlin-Dahlem, Free University of Berlin
last update 3 November 2005

primary / fruticose / foliose / squamulose / foliicolous / crustose / lichinaceae
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Primary key

1a Thallus compact or slightly tomentose, when viewed with a hand-lens; variously formed ---2
1b Thallus filamentose, when viewed with a hand-lens; forming a layer of loosely interwoven threads, appressed to the substrate or more or less free and forming semicircular plates ---5

2a Thallus flattened and more or less closely appressed to the substrate (foliose, squamulose or crustose) ---3
2b Thallus fruticose or dimorphic with fruticose part ---fruticose/dimorphic lichens
2c If thallus type indistinct and thallus gelatinous, homoiomerous, with coccoid cyanobacteria, each cell being enveloped by a separate gelatine sheet, see separate key for ---lichinaceae

3a Thallus directly attached to its substrate with most of its lower surface, not separable from it without much damage (crustose or squamulose) ---4
3b Thallus foliose, with lower side largely free and usually easily separated from from the substrate ---foliose lichens

4a Thallus squamulose, variously coloured ---squamulose lichens
4b Thallus minutely shrubby on medium magnification, green ---Macentina
4c Thallus compact on medium magnification, crustose or endophloeodic, variously coloured ---8

5a Thallus forming a blackish felt layer on rock ---6
5b Thallus forming bluegrey, greenish, yellowish or whitish, more or less free plates on bark or plant remains ---7

6a Thallus filaments covered by sinuous hyphae ---Cystocoleus
6b Thallus filaments covered by straight, parallel hyphae ---Racodium

7a Thallus bluegrey to whitish; ascocarps absent (basidiomycete); algae bluegreen ---Dictyonema
7b Thallus greenish to yellowish; yellow apothecia regularly present; algae Trentepohlia ---Coenogonium

8a Foliicolous species, found on living leaves ---foliicolous lichens
8b Corticolous, terrestrial or saxicolous species ---crustose lichens

primary / fruticose / foliose / squamulose / foliicolous / crustose
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About this key

After some preliminary work has been done towards a guide to neotropical lichen genera, it became clear that this project will not be finished soon. To make the results available at an early stage, a provisional version on INTERNET is presented. It will be expanded and improved gradually, as information becomes available.

How to use it? Depending on the availability of Internet access, three possible ways for use can be imagined. 1. The usual way for internet documents. 2. The files can be downloaded and accessed with a web brouser in the own computer. 3. Print-outs of the keys can be made and used like printed keys. It is advisable to downloan the files only shortly before use, as improvements are expected every few months.

The key treats c. 300 genera from the Neotropics, known either through published records or through recent, unpublished collections. Efforts have been made towards completeness. However, it should be kept in mind that the lichen flora of the Neotropics is poorly known and both genus delimitations and distribution patterns are incompletely known.

Basic knowledge of lichens or fungi is required for use of the key. For easier use a simplified terminology is applied. A glossary provides some explication for technical terms.

N.B. The number series of the couplets is incompletely used, because numbers are reserved for future extensions. Interruptions are marked by three blank lines.

As an aid towards species identification, as far as possible, an annotated list of genera is presented, which contains some information on distribution, represented species and available literature.

The key is based on one produced for the Flora of the Guianas. This is available on INTERNET: http://www.nmnh.si.edu/biodiversity/lichkey2.htm. The following persons, which are gratefully acknowledged for their contributions, have contributed to this Guianas key: R. C. Harris (1986), L. Brako (1986) , J. Knoph (1986), A. Aptroot (1996). 

The present key was supported by comments from A. Aptroot 1998, R. Lücking 1998, from the participants of a class on lichen determination held at the Pontificia Universidad Católica in Quito, Ecuador in August/September 1997, and from R. Welz, Berlin while working on his MSc thesis in 1999. A contribution on Lichinaceae was kindly provided by M. Schultz, 1999. Their co-operation is acknowledged with much gratitude! Further suggestions for improvement are coming in regularly, e.g., from N. Derakshani (Göttingen), M. Andersson (Göttingen), Adriano Spielmann (Santa Cruz do Sol), ...

It is planned to produce updated and extended versions of this key regularly. Therefore additions, corrections, recommendations are very welcome! Please contact Harrie Sipman, who would appreciate such co-operation very much. E-mail: hsipman@zedat.fu-berlin.de.

primary / fruticose / foliose / squamulose / foliicolous / crustose
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General literature

General identification books for tropical lichens (may be to some extent outdated):

• Aptroot, A. 1991. Tropical pyrenocarpous lichens. A phylogenetic approach [with key to tropical pyrenocarpous lichen genera). pp. 253-273 in D.J. Galloway (ed.), Tropical lichens: their systematics, conservation, and ecology. Systematics Association Special Volume 43.
• Awasthi, D. D. 1991. A key to the Microlichens of India, Nepal and Sri Lanka. Bibliotheca Lichenologica 40. 337 pp.
• Awasthi, D. D. 1988. A key to the Macrolichens of India and Nepal. Journ. Hattori Bot. Lab. 65: 207-302.
• Harris, R. D. 1990. Some Florida lichens. Published by the author, New York Botanical garden, 109 pp.
• Harris, R. D. 1995. More Florida lichens, including the 10c tour of the pyrenolichens. Published by the author, New York Botanical garden, 192 pp.
• Hawksworth, D. L. & Ahti, T. 1990. A bibliographic guide to the lichen floras of the world (Second edition).Lichenologist 22: 1-78.
• Galloway, D. J. 1985. Flora of New Zealand, Lichens. 662 pp., Wellington, New Zealand.
• Lücking, R. 1992. Foliicolous Lichens - A Contribution to the Knowledge of the Lichen Flora of Costa Rica, Central America. Beihefte zur Nova Hedwigia 104. (keys to foliicolous lichens of Costa Rica)
• Räsänen, V. 1943. Das System der Flechten. Acta Bot. Fenn. 33: 1-82.
• Santesson, R. 1952. Foliicolous Lichens 1. A revision of the taxonomy of the obligately foliicolous , lichenized fungi. Symbolae Bot. Upsal. XII (1). 590 pp.
• Swinscow, T. D. V. & H. Krog, 1988. Macrolichens of East Africa. 390 pp., British Museum (Natural History).
• Thrower, S. L. 1988. Hong Kong Lichens. 193 pp. Urban Council, Hong Kong. (c. 140 species, with colour photographs)
• Yoshimura, I. 1974. Lichen flora of Japan in colour. 349 pp. (in Japanese, many illustrations)
• Zahlbruckner, A. 1926. Lichenes (Flechten), Spezeller Teil, in A. Engler (ed.), Die Natürliche Pflanzenfamilien Bd. 8.

Many high-elevation lichens can be found in books for temperate regions, e.g.:

• Purvis, O. W., Coppins, B. J., Hawksworth, D. L., James, P. W. & Moore, D. M. 1992. The lichen flora of Great Britain and Ireland. Natural History Museum, London. 710 pages.
• I. M. Brodo et al. 2001. Lichens of North America. Yale University Press, New Haven and London. 795 pages.
• T.H. Nash III et al. 2002. Lichen Flora of the Greater Sonoran Desert Region. Arizona State University, Tempe. 532 pages.

Spanish/Portuguese treatments of particular interest for the Neotropics:

• Xavier Filho, L. & Rizzini, C. T., 1976. Manual de Liquenologia brasileiro. 433 pp., Univ. Federal de Pernambuco. (contains key to genera of Brazilian lichens, based on Zahlbruckner, see above).
• Marcano, V. 1994. Colección Flora Liquénica de los Andes Venezolanos. Vol. 1. Introducción al estudio de los líquenes y su clasificación. Edición de FUNDACITE Mérida, Serie Museo de Ciencia, Tecnología, Artes y Oficios. 338 pages. Available from: FUNDACITE-Mérida, P.O. Box 234, Mérida 5101A, Venezuela; fax (074) 44 52 17. (This first volume in a planned series of four covers mainly general chapters: survey of lichen exploration in Venezuela, general morphology, phylogeny, ecology, anatomy, physiology, chemistry, pharmacology, survey of orders, families and genera with their principal characters; about half of the volume contains colour photographs of representatives of the families with ecological and morphological data; in Spanish.)
• Sipman, H. J. M. & Aguirre C., J. 1982: Contribucion al conocimiento de los líquenes de Colombia - I. Clave generica para los líquenes foliosos y fruticosos de los paramos colombianos. - Caldasia 13(64): 603-634.
• De Valencia, M. & Aguirre C., J. 1995. Líquenes. Morfologia, Anatomia, Systemática. 142 Pages. Published by Universidad Nacional de Colombia, Bogota. (An introduction to lichens for students, containing chapters on ecology, morphology, chemistry, taxonomy, a key to the macrolichen genera of Colombia, short descriptions, and in part drawings, of these genera, instructions for collecting and classes; in Spanish.)

Specialized keys:

• foliicolous lichens: Lücking, R. 1992a: Foliicolous lichens - A contribution to the knowledge of the lichen flora of Costa Rica, Central America. - Beih. Nova Hedwigia 104: 1-179. See also website with checklist, good photographs, worldwide identification keys for the genera.
• Parmeliaceae: Adler, M. T. 1990: An artificial key to the genera of the Parmeliaceae (Lichenes, Ascomycotina). Mycotaxon 38: 331-347.
• Caliciales: Tibell, L. 1996, Caliciales. Flora Neotropica 69.

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Glossary of technical terms

Some terms are used in this key in a wide sense, and may be used in a more restricted sense in other works. Added are derived forms of the word: plural, adjective.

• acicular (ascospore) - needle-shaped: elongate and narrow, rarely over 2 µm wide.
• acrogenous (conidiophore) - unbranched conidiophore producing conidia terminally.
• anastomose / anastomosing (parahyses) - transverse connecting branchlets between paraphyses.
• apical dome - thickened apical part of ascus (tholus).
• apothecium / apothecia, apothecial - disc-shaped ascocarp, with widely exposed hymenium.
• arachnoid - with felty or cobwebby structure.
• ascocarp - generatively produced fruit body of ascomycete, which contains asci; three types: apothecium, perithecium, lirel.
• ascospore - spore produced in ascus.
• ascus / asci - spore-producing organ of sexual reproduction in ascomycetes; spores are produced internally in vesicles called asci, often in groups of 8.
• atranorin - lichen substance producing colour reactions P-, K+ yellow, C-, KC-.
• axial mass - I-negative central area in apical dome (tholus) of ascus.
• bacillar (spore) - rod-shaped, elongate, over c. 4 times as long as wide.
• basidiocarp - generatively produced fruit body of basidiomycete, which carries basidia producing basidiospores on little stalks.
• biatorine (apothecium) - apothecium with margin of same colour as disc, both not carbonised.
• byssoid (thallus) - thallus entirely composed of very loose hyphae, without compacted cortex.
• C+ (followed by colour) - see colour reaction.
• campylidium / campylidia - conidangium with ear-shaped spout.
• canaliculate (thallus lobes) - channel-like, with concave upper side and convex lower side.
• capitate (soralia) - soredium in form of low wart.
• carbonaceous / carbonized (tissue) - dark brown to black and charcoal-like, without distinct hyphal or cellular structure.
• cephalodium / cephalodia - specialised part with a blue-green photobiont of a thallus containing a green alga as photobiont.
• cilium / cilia, ciliate - thread-like appendix of thallus, composed of a bundle of hyphae and placed on the margin or upper side of the thallus.
• colour reaction - spot test on lichen thallus causing a colour change; the following reagents are commonly used: P: paraphenylene diamine solution (several recipes); K: 10 KOH solution in water; C: Na- or K-hypochlorite solution; KC: successive application of K and C.
• columella (hymenium) - more or less columnar mass of sterile, often carbonized, tissue in hymenium of certain Thelotremataceae.
• conidangium / conidangia - organ producing vegetative spores called conidia; ex.: pycnidium, campylidium, hyphophore.
• conidium / conidia, conidial - see conidangia; shape may range from ovoid to bacillar or filiform, occasionally branched.
• conidiophore - specialised hyphe inside conidangium producing conidia.
• cortex / cortical / corticate - compact superficial layer of thallus; a cortex may consist of compacted, but unchanged hyphae (prosoplectenchyma) or of hyphae with wide and rounded lumina (paraplectenchyma).
• corticolous - growing on bark.
• crustose - thallus covering the substrate with a tightly attached layer.
• cubical (spore lumina) - lumina in spores with thin septa and walls, in cross section showing edged corners.
• cyphella / cyphellae, cyphellate - crater-like pore in lower cortex of some foliose lichens.
• dimorphic - thallus composed of a fruticose and a squamulose or crustose part.
• disc - upper surface of hymenium in apothecium, mostly well recognisable by a different colour.
• endophloeiodic - thallus growing inside the empty cells of the cork layer of the substrate tree.
• endospore - spore wall substance of thick-walled spores.
• epigaeic - thallus growing on soil.
• epilithic - thallus growing on stone.
• epiphytic - thallus growing on living plants, usually on bark.
• epithecial algae - photobiont cells growing on the epithecium layer of an apothecium.
• epithecium / epithecia, epithecial - top layer of hymenium, mostly differentiated by presence of a pigment, granular substance and/or swollen or branched paraphyse tips.
• excipulum / excipula, excipular - Marginal part of ascocarp consisting of sterile tissue.
• filamentose - thallus composed of loosely interwoven filaments c. 0.1 mm diam., which are visible with a hand lens (c. 10x).
• foliicolous - growing on living leaves.
• foliose - thallus forming a sheet over the substrate with underside largely free from substrate, attached by small spots or rhizines.
• fruticose - thallus with free-standing or hanging, cylindrical or flattened, often branched lobes, which may measure a few mm to several dm in length, and which are affixed only at their base, rather uniformly coloured on all sides.
• fusiform (ascospore) - elongate and gradually attenuated towards the ends, up to about 4 times as long as wide.
• goniocyst - soredium-like structure, in which the fungal hyphae form a paraplectenchymatic outer layer.
• goniocystangium / goniocystangia - structure in which goniocysts are produced.
• granular (thallus surface) - with rounded, corticate grains.
• guttulate (hymenium) - troubled by small, droplet-like inclusions.
• halo / halonate - gelatinous sheath surrounding the ascospores in some species.
• heteromerous (thallus) - thallus composed of differentiated layer, usually an upper cortex, a layer containing the photobiont, and a medulla.
• homoiomerous (thallus) - thallus of similar structure throughout, with photobiont spread throughout the thallus.
• hymenial algae - photobiont cells growing inside the hymenium of an apothecium.
• hymenium / hymenia, hymenial - layer in the ascocarp, in which the asci are contained, usually among palisade-like paraphyses.
• hyphophore - hair- or sometimes scale-like appendix of thallus, which supports one or more drop-like, gelatinous masses with bundles of hyphae producing terminal conidia.
• hypothecium / hypothecia - apothecium layer below the hymenium, often differentiated by colour.
• K+ (followed by colour) - see colour reaction.
• KC+ (followed by colour) - see colour reaction.
• I+ - colour reaction caused by the application of iodine solution (e.g., Lugol, Meltzer's, IKI).
• isidium / isidia, isidiate, isidiose - small, cylindrical to globular, corticate structure on thallus, which falls off easily and serves probably for vegetative reproduction.
• labium / labia - lip-shaped margin of lirel.
• labriform (soralia) - lip-shaped soralia, in which the soredia are produced on the up-curled lower side.
• lecanorine (margin) - margin of apothecium which contains photobiont cells, resembles the thallus in colour and differs clearly from the disc.
• lecideine (margin) - dark brown to black, carbonised margin of apothecium.
• lenticular (spore lumina) - lens-shaped lumina in spores with thickened septa.
• leprose (thallus) - thallus arachnoid and producing soredia over entire surface, without compacted cortex.
• lignicolous - growing on wood.
• lirel / lirellae, lirellate - elongate ascocarps, opening by a split or with a strap-shaped disc.
• lobe - rounded sector of foliose thallus.
• lobule - small, lobe-like sprouts along the margin of on the upper surface of a foliose thallus.
• locule - cell-like cavity of ascospore.
• lumbricoid (spores) - worm-shaped.
• lumen / lumina - cavity of spore segments ("cells").
• macrocephalic (spore) - spore with less septa on one side and there with a single, large lumen.
• macroconidium / macroconidia - larger conidium type in species with different conidium types.
• mazaedium / mazaedia - specialised top layer of apothecium in some species, composed of spore masses and scattered criss-cross hyphae: in these species the spores are liberated from the asci before they are ripe and ripen in the mazaedium.
• merocarp - part of ascocarp with separate disc in species where ascocarps produce several discs.
• microconidium / microconidia - smaller conidium-type in species with different conidium types; microconidia are supposed to serve as spermatia and to be the proper pycnospores.
• muriform (ascospores) - spores with transverse and longitudinal septa.
• ocular chamber - central dent in the tholus of an ascus.
• ostiole - pore-like opening of perithecium or conidangium.
• P+ (followed by colour) - see colour reaction.
• paraphyse(s) - sterile hyphae surrounding the asci in the hymenium.
• paraplectenchymatic - hyphal "tissue" in which the lumina are much swollen and give the aspect of a parenchyma.
• periphyse(s) – parallel, free-standing hyphae, resembling paraphyses but implanted on the excipulum above the hymenium, in perithecia around the ostiole.
• perithecium / perithecia - ascocarp with wall closed above the hymenium, opening by a small pore.
• phyllocladium / phyllocladia - squamulose or coralloid appendages of fruticose lichens, in which the photobiont is largely restricted to these appendages.
• photobiont - associated alga of a lichen.
• pleurogenous (conidiophore) - more or less branched conidiophores, which produce conidia on lateral processes of the composing cells.
• podetium / podetia - fruticose part of some lichens with dimorphic thallus; ontogenetically derived from stalk-like elongated apothecium base.
• polarilocular (ascospores) - elongate ascospores with thick central septum and locules situated close to the poles.
• prosoplectenchymatic - hyphal tissue in which the lumina are not much swollen but the walls much thickened and conglutinated to form a compact layer with scattered, elongate lumina.
• prothallus - marginal zone without algae surrounding (crustose) thallus.
• pruina / pruinose - farinose- or frosty-looking surface cover.
• pseudocyphella / pseudocyphellae, pseudocyphellate - interruption in thallus cortex showing as a whitish spot.
• pseudopodetium / pseudopodetia - fruticose part of some lichens with dimorphic thallus; not ontogenetically derived from apothecium.
• pseudostroma - ascocarps with several discs or pores.
• psoromic acid - lichen substance producing colour reactions P+ yellow, K-, C-, KC-.
• pustule / pustulate, pustular - irregular-warty, often fragile and flaking superficial thallus structure, probably serving vegetative reproduction.
• pycnidium / pycnidia - type of conidangium in lichens, of which the conidia serve probably as spermatia.
• pycnoconidium / pycnoconidia - conidium produced in pycnidium.
• pycnospore - conidium produced in pycnidium.
• rhizine - thread-like appendix on lower side of foliose thallus, composed of bundled hyphae.
• saxicolous - growing on rock.
• schizidium / schizidia - specialised, flake-like thallus parts, which are shed as means of vegetative reproduction.
• soralium /soralia - specialised spot on thallus surface which produces tiny, non-corticate thallus granules composed of photobiont cells and hyphae.
• soredium / soredia, sorediate, sorediose - tiny, non-corticate, flour-like thallus granules produced in soralia.
• squamule / squamulose - scale-like thallus part, lower side largely attached to the substrate, but free towards the tip.
• stictic acid - lichen substance producing colour reactions P+ orange, K+ yellow-orange, C-, KC-.
• stromatoid (ascocarp) - ascocarp with several discs or pores = pseudostroma.
• terrestrial - growing on soil.
• terricolous - growing on soil.
• thallus / thalline, thalloid - part of lichen homologous with mycelium, consisting of compacted hyphae and photobiont cells, forming a crust-like, paper-like or shrubby structure, supporting the ascocarps and conidangia.
• tholus - thickened upper part of ascus.
• tomentum / tomentose - woolly or furry layer of loose hyphae.
• umbilicus / umbilicate - central attachment spot of some foliose lichens.
• usnic acid - lichen substance, producing colour reactions P-, K-, C-, KC+ yellow.

primary / fruticose / foliose / squamulose / foliicolous / crustose / lichinaceae
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