Peltigera is a genus of approximately 100 species of foliose lichen in the family Peltigeraceae.
Most species of Peltigera have the cyanobacterium Nostoc as the dominant Lichen but some have the algae Coccomyxa. The presence of both a green alga and a cyanobacterium makes some tripartite; in this case they show cephalodium growths containing the third partner, Nostoc. Because of their ability to fix nitrogen from the atmosphere, such lichens are influential in soil composition and generation.
Description
Species of
Peltigera are
Foliose lichen, with broad lobed
thallus. Although the size of the thalli is variable and species-dependent, in some species the thalli can grow quite large, up to 30 cm in diameter.
[Vitikainen O. (1994). (1998). Taxonomic notes on neotropical species of Pelitgera. In: Lichenology in Latin America: history, current knowledge and applications. Edited by M. P. Marcelli, and M.R.D. Seaward. CETESB, Companhia de Tecnologia de Saneamento Ambiental, Estado de Sao Paulo. pp. 135-139.] The color of the upper surface may range from drab gray, brown or greenish. Lower surfaces are typically
without a cortex (unlike other
),
[ Fioliose lichens, Lichen Thallus Types, Allan Silverside] and cottony, often with fungal
hyphae fused to form a network of veins. The reproductive structures
isidium,
soredium or may be present in some species.
All species of
Peltigera associate with the nitrogen-fixing cyanobacteria
Nostoc.
Peltigera can be distinguished from the equally large and leaf-like lichen, Nephroma, by its veined lower cortex; Nephroma, by contrast, has a smooth, unveined lower cortex.
Habitat
Peltigera are mainly ground-dwelling, but can also be found on mosses or dead wood.
Some species are used as forest succession indicators.
Taxonomy
In 1753,
Carl Linnaeus first described the species
Lichen apthosus and
L. caninus back when all known lichens were grouped into the genus
Lichen.
[Linnaeus C. (1753). Species plantarum. Stockholm.] Later, in 1787, Carl Ludwig Willdenow circumscribed the genus
Peltigera, and redescribed
P. aphthosa and
Peltigera canina.
The generic name is derived from the Latin pelta (small shield), and refers to the shield-shaped thallus in these species. The common name, the dog lichen, refers to the perceived resemblance of P. caninus to a dog.
Phylogeny
In a comparative analysis of both morphological and chemical characteristics as well as sequences of large subunit nuclear
ribosomal DNA, it was shown that the genus
Peltigera is
monophyletic.
Several species, such as
Peltigera canina, have been changed to a group as there appears to be several species clustered under a single name.
Recent taxonomic work has led to the consolidation of three previously recognized aquatic Peltigera species ( P. hydrothyria, P. gowardii, and P. aquatica) into a single species with three varieties. According to Bruce McCune and Daphne Stone (2022), while molecular analysis showed three distinct genetic , maintaining them as separate species proved impractical for conservation and research purposes. This was because P. gowardii and P. aquatica, which occur together in western North America, are indistinguishable without DNA sequencing. The difficulty in identifying specimens to species level effectively stalled data collection, with most specimens remaining classified only as P. hydrothyria sensu lato. To resolve this issue while preserving information about genetic diversity, the three taxa were reclassified as P. hydrothyria var. hydrothyria (eastern North America), P. hydrothyria var. gowardii (western), and P. hydrothyria var. aquatica (western). This taxonomic solution allows for practical field identification while still acknowledging the genetic differences between populations.
Distribution
The
Peltigera have a widespread distribution, and are found on all continents. There are 34
species,
30
species,
25 species from
South America, and 16 species from
New Zealand.
There are 27
Peltigera species that have been recorded from China.
Ecology
Peltigera lichens serve as important hosts for diverse microbial communities, functioning as miniature ecosystems rather than simply dual symbiotic partnerships. Recent research has revealed that
Peltigera species harbour rich communities of
Basidiomycota yeasts, with some species supporting multiple distinct
yeast taxa within their thalli. For example,
P. rufescens has been found to host over 90 different yeast isolates representing 18 distinct taxa, demonstrating the complexity of these microbial associations. These lichens appear to acquire key microbial symbionts directly from the soils where they grow, suggesting their local environments serve as reservoirs for their
microbiome diversity.
The yeasts associated with Peltigera belong to several major taxonomic groups, including members of the classes Tremellomycetes, Cystobasidiomycetes, and other basidiomycetes. Many of these yeasts are psychrotolerant, showing adaptations to cold environments, which may enhance the lichens' ability to survive in harsh conditions. This characteristic likely contributes to the successful colonisation of various habitats by Peltigera species, particularly in temperate and cold regions where they are commonly found. Studies have shown that these yeasts can maintain metabolic activity even at low temperatures, potentially supporting the lichen's overall survival and ecological functionality.
The relationship between Peltigera and its microbial communities appears to vary across different environments and species. Research in southern Chile has demonstrated that Peltigera lichens can enhance gamma diversity across landscapes by functioning as island-like habitats that support specialised bacteria and yeasts. This suggests that Peltigera species play a broader ecological role beyond their own survival, contributing to local microbial biodiversity patterns and ecosystem processes. While the specific functions of many associated microorganisms remain under investigation, this complex microbial diversity likely contributes to the ecological resilience of Peltigera species across different environments and may help explain their successful colonisation of diverse habitats worldwide.
Species
-
Peltigera alkalicola
-
Peltigera aphthosa
-
Peltigera appalachiensis
-
Peltigera asiatica
-
Peltigera borealis
-
Peltigera borinquensis
-
Peltigera britannica
-
Peltigera canina
-
Peltigera castanea
-
Peltigera chabanenkoae
-
Peltigera chionophila
-
Peltigera cinnamomea
-
Peltigera clathrata
-
Peltigera collina
-
Peltigera degenii
-
Peltigera didactyla
-
Peltigera dilacerata
-
Peltigera dolichorhiza
-
Peltigera elisabethae
-
Peltigera elixii
-
Peltigera esslingeri
-
Peltigera evansiana
-
Peltigera extenuata
-
Peltigera fibrilloides
-
Peltigera fimbriata
-
Peltigera flabellae
-
Peltigera frigida
-
Peltigera frippii
-
Peltigera gallowayi
-
Peltigera globulata
-
Peltigera granulosa
-
Peltigera hawaiiensis
-
Peltigera hokkaidoensis
-
Peltigera holtanhartwigii
-
Peltigera horizontalis
-
Peltigera hydrophila
-
Peltigera hydrothyria
-
Peltigera hymenina
-
Peltigera isidiophora
-
Peltigera islandica
-
Peltigera itatiaiae
-
Peltigera koponenii
-
Peltigera kristinssonii
-
Peltigera kukwae
-
Peltigera lactucifolia
-
Peltigera lairdii
-
Peltigera latiloba
-
Peltigera lepidophora
-
Peltigera leptoderma
-
Peltigera leucophlebia
-
Peltigera malacea
-
Peltigera massonii
-
Peltigera melanorrhiza
-
Peltigera membranacea
-
Peltigera mikado
-
Peltigera montis-wilhelmii
-
Peltigera neckeri
-
Peltigera neodegenii
-
Peltigera neopolydactyla
-
Peltigera neorufescens
-
Peltigera nigriventris
-
Peltigera occidentalis
-
Peltigera orientalis
-
Peltigera pacifica
-
Peltigera papuana
-
Peltigera phyllidiosa
-
Peltigera polydactylon
-
Peltigera ponojensis
-
Peltigera praetextata
-
Peltigera pulverulenta
-
Peltigera pusilla
-
Peltigera rangiferina
-
Peltigera retifoveata
-
Peltigera rufescens
-
Peltigera rufescentiformis
-
Peltigera scabrosa
-
Peltigera scabrosella
-
Peltigera seneca
-
Peltigera serusiauxii
-
Peltigera shennongjiana
-
Peltigera sipmanii
-
Peltigera sorediifera
-
Peltigera stanleyensis
-
Peltigera subhorizontalis
-
Peltigera tartarea
-
Peltigera tereziana
-
Peltigera ulcerata
-
Peltigera vainioi
-
Peltigera venosa
-
Peltigera vitikainenii
-
Peltigera weberi
-
Peltigera willdenowii
-
Peltigera wulingensis
Uses
Peltigera species have been used historically to treat wounds, urinary disorders,
Candidiasis,
tuberculosis, and
rabies.
was used as a remedy for cough
and infantile
aphthae.
[Vartia KO. (1950). On the medicinal use of lichens. Academic dissertation. Helsinki: 11–21.]
P. furfuracea has shown potent antioxidant activity and reducing power.
Similarly,
Peltigera specimens from Hawaii and Iceland have also been reported to show pronounced antioxidant activity.
Food source
Although a few reports have described
caribou and
reindeer feeding on the
Thallus of
Peltigera,
in general, species of
Peltigera are not commonly used as a food source by mammals.
A study of the grazing habits of the land snails
Cantareus aspersa and
Limax species revealed that these snails prefer to eat
Peltigera species (such as
P. praetextata) that are lacking in secondary metabolites.
Bioactive compounds
Peltigera leucophlebia contains the compounds
tenuiorin and methyl orsellinate, which are
enzyme inhibitor to the enzyme 15-
lipoxygenase.
Tenuiorin is also known to occur in
P. apthosa,
P. malacea and
P. neckeri.
A mixture of methyl and ethyl orsellinates have been identified from
P. aphthosa that had
antibacterial activity against Gram-positive and -negative bacteria.
The novel non-protein amino acids solorinine and peltigerine have been detected in various species of
Peltigera.
