A Preliminary World-wide Key to the Lichen Genus Pertusaria

A.W. Archer & J.A. Elix

The lichen genus Pertusaria (Pertusariaceae) is widely distributed throughout the world, from equatorial to polar regions (Dibben 1980; Lumbsch & Nash 2001). Species may grow on bark, rock, soil, plant débris and mosses and are differentiated by the apothecial structure (disciform or verruciform), the number and structure of the ascospores (1, 2, 4 or 8 per ascus, smooth- or rough-walled ascospores) and the chemistry (Dibben 1980; Archer 1997). Chemistry has been recognised as an important taxonomic tool in the identification of species in the genus Pertusaria (Lumbsch 1998).

The chemistry of the genus Pertusaria has been reported in many publications. Oshio (1968) reported the colour reactions of Japanese species and the compounds producing these colours were subsequently identified by Dibben (1975) who later published the chemistry of North American Pertusaria (1980). Similarly, Poelt and Vĕzda (1981) described the colour reactions of European species of Pertusaria and the identity of these compounds was later determined by Hanko (1983). Additional synonymy and chemical data for a range of European taxa was reported by Niebel-Lohmann and Feuerer (1992). Chemical data on many type specimens was reported by Archer (1993, 1995) and the chemistry of Australian Pertusaria published (Archer 1997). Additional type specimens hace since been examined and their chemistries determined. A current Key to European Pertusaria (Sipman, www.bgbm.org/BGBM/Staff/Wiss/Sipman/keys/perteuro.htm) contains much chemical information on European taxa, which has been included in this Key. Modern descriptions of new taxa in the genus would now be regarded as incomplete without a report of the chemistry.

The total number of species in the genus is not accurately known. Nash et al. (2001) suggest ca. 350 species. Archer & Messuti (2009) calculated a possible 1550 species out of a theoretically possible 3500 chemical and morphological combinations (Archer 1997) while the Index Fungorum (www.indexfungorum.org) lists 1770 taxa, which, however, include many forms and varieties. For example, P. coccodes (Ach.) Nyl. has 17 forms and 10 varieties.

This Key includes 794 taxa, together with 482 synonyms or possible synonyms which are listed following the Key. Taxa with synonyms are indicated by: ; clicking on this will open the alphabetical list of synonyms.

The genus is represented in Australia by 133 species and 9 varieties, of which 61 species and the 9 varieties are endemic. 65 species (ca. 50% of the known species in Australia) and 4 varieties are found in New South Wales.

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Chemistry

The compounds found in the genus Pertusaria fall into 8 categories:

Xanthones such as lichexanthone, 4,5-dichlorolichexanthone and thiophaninic acid.
Orcinol p-depsides such as lecanoric and gyrophoric acid.
Homologues of orcinol p-depsides such as perlatolic acid and its derivatives.
Orcinol depsones such as picrolichenic acid and its homologues.
β-Orcinol m-depsides such as hypothamnolic and thamnolic acids.
β-Orcinol p-depsides such as squamatic and barbatic acids.
β-Orcinol depsidones such as stictic, norstictic, psoromic and protocetraric acids.
Aliphatic acids such as allopertusaric acid and lichesterinic acid.

In addition, some taxa lack lichen compounds.

References

Archer, A.W. (1997) A chemical and morphological arrangement of the lichen genus Pertusaria in Australia. Bibliotheca Lichenologica 53:1-17.
Archer, A.W. (1995) A chemical and morphological arrangement of the lichen genus Pertusaria in Australia;: additional data and corrections. Mycotaxon 55:385-389.
Archer, A.W. (1997) The lichen genus Pertusaria in Australia. Bibliotheca Lichenologica 69:5-249.
Dibben, M.J. (1975) The Chemosystematics of the lichen genus Pertusaria in North America north of Mexico. Appendix II, Exotic species, pp. 492-519, Ph.D. thesis, Duke University.
Dibben, M.J. (1980) The Chemosystematics of the lichen genus Pertusaria in North America north of Mexico. Milwaukee Publications in Biology and Geology 5: 1-162.
Hanko, B. (1983) Die Chemotypen der Flechtengattung in Europa. Bibliotheca Lichenologica 19:3-296.
Lumbsch, H.T. (1998) Taxonomic use of metabolic data in lichen-forming fungi. In: Frisvald, J.C., Bridge, P.D. & Arora, D.K (eds.) Chemical fungal taxonomy: 345-387. Marcel Dekker, New York.
Lumbsch, H.T. & Nash, T.H (2001) Pertusaria in Nash, H.T., Ryan, B.D., Gries, C & Bungartz, F. Lichen Flora of the Greater Sonoran Desert Region 1: 341-357
Messuti, M.I. & Archer, A.W. (2009) ¿Cuántos taxones pueden incluirse teóricamente en el género Pertusaria? Glalia 2(1): 1-9.
Niebel-Lohmann, A. & Feuerer, T. (1992). Die Gattung Pertusaria DC (Lichenes) in Schleswig-Holstein: Anatomie, Morphologie Taxonomie und Verbreitung 1. Mitt. Inst. Allg. Bot. Hamburg. 24: 199-252.
Oshio, M (1968) Taxonomical studies on the family Pertusariaceae of Japan. Journal of Science of the Hiroshima University, B(2), 12: 81-163.
Poelt, J. & Vezda, A. (1981). Pertusaria in Bestimmungsschlüssel europäischer Flechten. Ergänzungheft II. Bibliotheca Lichenologica 16: 1-390.

Notes

The key uses apothecial structure and number and type of ascospores to place specimens in appropriate Groups (vide infra). Within the Groups chemical constituents, and size and arrangement of ascospores, are used to distinguish species. Synomyms and possible synonyms are indicated.
Only major chemical constituents are referred to and there remain species whose chemistry is unknown; these species are omitted until their chemistry is determined and published.
Where the results of chemical tests (K, C, etc.) are reported and give a strong indication of the substance(s) present, these species are tentatively included.
Rock includes species growing on soil and plant débris, and mosses.
Disciform species include species where the apothecia is disciform and either sessile or raised in protuberances.
Sterile sorediate or isidiate species include species that may also occur as fertile specimens; sorediate or isidiate species which are always fertile are included in the appropriate fertile Group. Taxa which are reported to occur on both wood and rock are included twice.
Species with 2-3, or 2-4 ascospores per ascus are included in the 4-spored species; species with 6, 7 or 8 ascospores are inclcuded in 8-spored species.

Search

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Pertusaria glomellerifica Elix & A.W. Archer x4 The yellow colour is due to the presence of the xanthone, thiophaninic acid.

Typical Pertusaria spores [from P. glomellerifica]. Each spore has a double wall and is about 90 µm long.

Key

Group 1. Apothecia absent; isidia present; on rock
Group 2. Apothecia absent; isidia present; on wood
Group 3. Apothecia absent; soredia present; on rock
Group 4. Apothecia absent; soredia present; on wood

Group 5. Apothecia present, verruciform; ascospores 1 per ascus; on rock
Group 6. Apothecia present, verruciform; ascospores 1 per ascus; on wood
Group 7. Apothecia present, disciform; ascospores 1 per ascus; on rock
Group 8. Apothecia present, disciform; ascospores 1 per ascus; on wood

Group 9. Apothecia present, disciform; ascospores 2 per ascus; on wood
Group 10 Apothecia, present disciform; ascospores 2 per ascus; on rock

Group 11. Apothecia present, verruciform; ascospores 2 per ascus, smooth; on rock
Group 12. Apothecia present, verruciform; ascospores 2 per ascus, rough; on rock
Group 13. Apothecia present, verruciform; ascospores 2 per ascus, smooth; on wood
Group 14. Apothecia present, verruciform; ascospores 2 per ascus, rough; on wood

Group 15. Apothecia present, verruciform; ascospores 4 per ascus, smooth; on rock
Group 16. Apothecia present, verruciform; ascospores 4 per ascus, rough; on rock
Group 17. Apothecia present, verruciform; ascospores 4 per ascus, smooth; on wood
Group 18. Apothecia present, verruciform; ascospores 4 per ascus, rough; on wood

Group 19. Apothecia present, disciform; ascospores 8 per ascus, on rock
Group 20. Apothecia present, disciform; ascospores 8 per ascus, on wood
Group 21. Apothecia present, verruciform; ascospores 8 per ascus, on rock
Group 22. Apothecia present, verruciform; ascospores 8 per ascus, on wood

Sterile, lacking isidia, soredia and apothecia.

P. shenandoensis Hale & Dibben; saxicolous; norstictic acid present; N.Am
P. scepusiensis (Gyeln.) Erichs.; saxicolous; P-ve; Eur.

Botanic Gardens Trust, Sydney, Australia