Lichen Nomenclature

Lichen Nomenclature - Supplementary notes for the Taxon Dictionary

Current Taxon Name

This is the currently accepted name for use by the BLS Databases and on the latest versions of mapping cards; likewise, the NBN Gateway, although more recent name changes may take a year or two to be recognized by that facility.

A Current Taxon Name is not necessarily the most taxonomically correct, nor the most correct as regarding the Rules of the ‘Code’ [International Code of Nomenclature for Algae, Fungi and Plants, formerly International Code of Botanical Nomenclature]. Proposed changes arising from recent research are often not adopted immediately, so as to allow the ‘dust to settle’ and for the ramifications of the proposals to be resolved. For example, many of the splits in the large genus Verrucaria based on phylogenetic studies have not yet been adopted as many species remain to be studied by molecular techniques. This does not mean that the ‘splits’ are not taxonomically meaningful, more that they are part of ‘work in progress’. However, the changed names are given as Synonyms with an appropriate statement in the Comments column.

A few as yet unpublished names, used for taxa recognized by recorders, are included and indicated by the suffixes “ad int.” or “ined.”

For the purposes of recording, the Current Taxon Name column includes a few aggregate taxa. This is for two reasons, or a combination of both. Punctelia subrudecta s. lat. [= P. subrudecta in the broad sense] is for records made before the two component taxa, P. jeckeri and P. subrudecta s. str. [in the strict sense] were commonly separated. The aggregate name can also be used for current records where the recorder is unable to make a critical determination. Other similar examples include Degelia plumbea s. lat. [D. cyanoloma and D. plumbea s. str.], and Lecidea fuscoatra s. lat. [L. fuscoatra s. str. and L. grisella]. A more complex situation exists in groups where taxonomic work is in progress. In this category is Caloplaca citrina s. lat., an aggregate that includes several commonly confused taxa, viz. Caloplaca arcis, C. dichroa, C. flavocitrina, C. limonia, C. phlogina, and perhaps also C. citrina s. str. if that species can be confirmed as a British taxon. In addition, a species akin to C. austrocitrina is also involved, and seems to be very common and widely distributed in Britain.


The Synonyms column includes most synonyms and misapplications appearing in publications subsequent to the second edition of Smith’s monograph (Smith 1918, 1926). Many earlier names are also included, but many more need to be added. The synonym list includes all lichenicolous fungi, greatly aided by David Hawksworth’s checklist (Hawksworth 2003). The compilation as provided here is certainly not comprehensive and will be added to and amended as appropriate. Similarly, the synonym list is unlikely to be devoid of mistakes, especially with regard to author citations!

The List includes not only synonyms in the strict sense, but also many misinterpretations and misapplications of names, and names of uncertain application. The misuses included are mainly those that have appeared in the published literature, but a few additional ones that are commonly met with in the study of herbarium material, and as handwritten entries on mapping cards, are also included. The study of herbarium material reveals many additional misidentifications, but it is unrealistic to account for all such eventualities.

What is a synonym?

In the strict sense, synonyms are of two types:

1. Nomenclatural synonyms, sometimes called homotypic synonyms. These are two or more names based on the same type; e.g. Parmelia reddenda Stirt. and Punctelia reddenda (Stirt.) Krog. Here, a species is transferred from one genus to another, and its species epithet is unchanged. Sometimes there is a slight change in the spelling of the species epithet because the generic name is of a different gender; e.g. Cetraria aculeata [feminine], Lichen aculeatus [masculine] and Coelocaulon aculeatum [neuter].

In some cases, the species epithet has had to change completely for reasons of priority. E.g. Stigmatidium dendriticum Leight. was considered by Peter James to belong to Arthonia. However, there already existed a different species with the name Arthonia dendritica, so an alternative name (a ‘nomen novum’) had to be coined. Hence, Stigmatidium dendriticum was published in Arthonia as Arthonia atlantica P. James.

2. Taxonomic synonyms, sometimes called heterotypic synonyms. This is where two or more names are based on different types but which are considered to belong to the same species. E.g. Collema fuscovirens (With.) J.R. Laundon and Collema tuniforme (Ach.) Ach.


The ‘biggest syns’ - misapplied names

If the updating of species lists was just a matter of converting old names to currently accepted names by their nomenclatural and taxonomic synonyms, the process could be done simply and mechanically. Unfortunately life is not so simple!

As a simple example, the type specimen of Lecidea prasinula has been shown to belong to Lecidella scabra. On the grounds of straight synonymy Lecidea prasinula and its nomenclatural synonym Lecidella prasinula are synonyms of Lecidella scabra. However, ‘prasinula’ had been used for decades for a different species, i.e. what we now call Lecidella meiococca. Most collections of prasinula, apart from the type collection, belong to L. meiococca. Hence:

Lecidella prasinula (Wedd.) Hertel = Lecidella scabra
Lecidella prasinula auct. = Lecidella meiococca

Many names have been partly misapplied because a broad concept was previously attributed to them. As examples, the ‘old’ Peltigera canina is now considered to comprise two species: P. canina and P. membranacea. The ‘old’ Peltigera polydactyla now comprises three species: P. polydactylon, P. hymenina and P. neckeri. The ‘old’ Physcia grisea now comprises Physconia grisea, P. enteroxantha and P. perisidiosa. The ‘old’ Peltigera aphthosa now comprises P. britannica and P. leucophlebia; there is also a ‘true’ P. aphthosa, but that species has not been correctly reported from the British Isles.

How to interpret the outcome of such splits is best accomplished by the re-determination of voucher specimens, where such exist. Where they do not exist, some intelligent guesswork can be made by considerations of the location, habitat and date of the record in relation to the known distribution, ecology, taxonomy and nomenclatural history of the species concerned. For example, a record of Peltigera canina made prior to about 1982, and from mossy tree bases in woodland, or mossy siliceous boulders, or acid grassland or dunes, is almost certain to be P. membranacea, which is also the much commoner of the two species. Similarly, a record of Peltigera polydactyla’ from grassland in southern England is most likely to be P. hymenina, as P. polydactylon is exceedingly rare in that region, whereas P. hymenina is widely distributed there. This does not always work, because if the record was on mossy rocks in the Pennines or Scotland, you may as well toss a coin!

The Synonyms list tries to take account of such things, and can doubtless be much improved in this respect. However, the list can deal only with the more common and important misapplication of names - it cannot take account of every misidentification to be found in the literature or the major herbaria! The misapplications listed are also restricted to those made in the British Isles.

Authority and Authority date

Authority gives the name(s) of the author(s) of a name. Many author names are abbreviated, and the abbreviations follow ‘Authors of Fungal Names’ by Kirk & Ansell (1992) and the Index Fungorum Authors of Fungal Names.

Sometimes the author names are replaced (or prefixed) by “auct.” [most authors] or “auct. brit.” [British authors], to indicate the use of a name other than that used by the original author(s) of the name. This mainly applies to misapplied names [listed as synonyms], but in a few cases for Current Taxon names where further research is required to elucidate the correct name; e.g. Arthonia elegans, Lecidea sanguineoatra, Verrucaria hydrela and V. murina.

The Authority date is given for current taxon names and a few synonyms. This refers to the date of valid publication of the name in its present form.

Abbreviations and annotations used in the checklist

A more comprehensive list of abbreviations and terminology can be found in ‘Terms used in Bionomenclature. The naming of organisms (and plant communities)’ by Hawksworth (2010) which can be downloaded as a PDF file.

ad int. = ad interim; provisionally – for a name used provisionally during a taxonomic study or until such a study is completed. Such names are not validly published according to the Code.

auct. = auctorum; of authors, usually meaning those other than the original person or person who originally described the taxon. Used for a name that has also been misapplied in countries outside the British Isles.

auct. brit. = auctorum britannicum; of British authors. [NB: Hawksworth (2003) uses auct. angl. = auctorum anglicum, although not all British authors are English; e.g., J.M. Crombie and W.L. Lindsay have Scottish origins!].

             auct. europ. = auctorum europaeum; of European authors.

comb. inval. = combination invalid; the name was not changed to a different genus according to the Code.

ined. = ineditus; unpublished, but usually meaning that it is expected to be.

in herb. = in herbarium; a name given on a herbarium label but never validly published.

nom. illeg. = nomen illegitimum; an illegitimate name according to the Code.

nom. inval. = nomen invalidum; an invalid name according to the Code.

nom. nud. = nomen nudum; a name not accompanied by a description or diagnosis or reference to a previously published description or diagnosis, and therefore not validly published according to the Code.

nom. rejic. = nomen rejiciendum; a name that has been formally rejected and is no longer available for use.

nom. rejic. prop. = as above, but in the proposal stage and not yet ratified

nom. superfl. = nomen superfluum; a superfluous name according to the Code.

orth. error = orthographic [spelling] error.

orth. var. = orthographic [spelling] variation.

p.p. = pro parte; in part.

p.max.p. = pro maxima parte; for the most part.

p.min.p. = pro minore parte; for the smaller part.

sed = but.

sensu = in the sense of [author(s) or collector(s)].

s. l. = sensu lato; see next.

s. lat. = sensu lato; in the broad sense of the name (i.e. including material agreeing with the nomenclatural type and other entities).

s. s. = sensu stricto; see next.

s. str. = sensu stricto; in the strict sense of the name (i.e. including only material agreeing with the nomenclatural type).

sphalm. = sphalmate; meaning by mistake or ‘slip of the pen’ or ‘slip on the keyboard’!

Updating the Syn List - how you can help

Studies in the taxonomy and nomenclature of lichens continue, and name changes are inevitable. Furthermore, detailed studies of historical collections give us a better understanding of the past uses (and abuses) of names by different authors and over different periods of time. Please send any relevant information pertaining to the Synonyms list, including suggested additions and corrections, and any other comments as to how you think the List can be improved to


[Includes some previous checklists not cited above]

Cannon, P.F., Hawksworth, D.L & Sherwood-Pike, M.A. (1985). The British Ascomycotina. An annotated checklist. Slough: Commonwealth Agricultural Bureaux.

Coppins, B.J. (2002). Checklist of Lichens of Great Britain and Ireland. London: British Lichen Society.

Hawksworth, D.L. (2003). The lichenicolous fungi of Great Britain and Ireland: an overview and annotated checklist. Lichenologist 35: 191–232.

Hawksworth, D.L., Coppins, B.J. & James, P.W. (1980). Checklist of British Lichen-forming, lichenicolous and allied fungi. Lichenologist 12: 1–115.

Hawksworth, D.L. (2010). Terms used in Bionomenclature. The naming of organisms (and plant communities). Copenhagen: Global Biodiversity Information Facility.

Kirk, P.M. & Ansell, A.E. (1992). Authors of Fungal Names. [Index of Fungi Supplement]. Wallingford: CAB International. [updated on the URL (].

Purvis, O.W., Coppins, B.J., Hawksworth, D.L., James, P.W. & Moore, D.M. (1992). The Lichen Flora of Great Britain and Ireland. London: Natural History Museum Publications & British Lichen Society.

Purvis, O.W., Coppins, B.J. & James, P.W. (1993). Checklist of lichens of Great Britain and Ireland. British Lichen Society Bulletin 72 (Suppl.): 1–75.

Purvis, O.W., Coppins, B.J. & James, P.W. (1994). Checklist of Lichens of Great Britain and Ireland. London: British Lichen Society.

Smith, A.L. (1918)A Monograph of the British Lichens, Vol. 1, 2 edn. London: British Museum (Natural History).

Smith, A.L. (1926). A Monograph of the British Lichens, Vol. 2, 2 edn. London: British Museum (Natural History).

Smith, C.W., Aptroot, A., Coppins, B.J., Fletcher, A., Gilbert, O.L., James, P.W. & Wolseley, P.A. (eds) (2009). The Lichens of Great Britain and Ireland. London: British Lichen Society.