Peltigera

Peltigera
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Peltigera leucophlebia
Scientific classification
Kingdom:	Fungi
Division:	Ascomycota
Class:	Lecanoromycetes
Order:	Peltigerales
Family:	Peltigeraceae
Genus:	Peltigera Willd.
Type species
Peltigera canina (L.) Willd.

Peltigera is a genus of approximately 91 species of foliose lichens in the family Peltigeraceae. Commonly known as the dog lichen, lichens of Peltigera are often terricolous (growing on soil), but can also occur on moss, trees, rocks, and many other substrates in many parts of the world.

Most Peltigera species have the cyanobacterium Nostoc as the dominant phytobiont but some have the chlorophyte Coccomyxa in which case they also have small gall-like growths containing 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, with broad lobed thalli. 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. The color of the upper surface may range from drab gray, brown or greenish. Lower surfaces are typically without a cortex (unlike other foliose lichens), and cottony, often with fungal hyphae fused to form a network of veins. The reproductive structures isidia, soredia or lobules may be present in some species.

All species of Peltigera associate with the nitrogen-fixing cyanobacteria Nostoc.

Habitat

P. didactyla is a common pioneer species on disturbed soils and nutrient poor grasslands in Western Europe. At Deception Island in the South Shetlands archipelago, P. didactyla was found growing extensively on ash from volcanic eruptions that occurred in the late 1960s and 1970.

Taxonomy

In 1753, Linnaeus first described the species Lichen apthosus and L. caninus back when all known lichens were grouped into the genus Lichen. Later, in 1787, Willdenow circumscribed the genus Peltigera, and redescribed P. aphthosa and P. canina.

The generic name is derived from the Latin language 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.

Distribution

The Peltigera have a widespread distribution, and are found on all continents. There are 34 North American species, 30 European species, 25 species from South America, and 16 species from New Zealand.

Species

• Peltigera aphthosa
• Peltigera aubertii
• Peltigera britannica
• Peltigera canina
• Peltigera chionophila
• Peltigera cichoracea
• Peltigera cinnamomea
• Peltigera collina
• Peltigera degenii
• Peltigera didactyla
• Peltigera dolichorhiza
• Peltigera dolichospora
• Peltigera elisabethae
• Peltigera erioderma
• Peltigera evansiana
• Peltigera fimbriata
• Peltigera frippii
• Peltigera granulosa
• Peltigera horizontalis
• Peltigera hydrothyria
• Peltigera koponenii
• Peltigera kristinssonii
• Peltigera lambinonii
• Peltigera leucophlebia
• Peltigera malacea
• Peltigera membranacea
• Peltigera montis-wilhelmii
• Peltigera nana
• Peltigera neopolydactyla
• Peltigera occidentalis
• Peltigera oceanica
• Peltigera pacifica
• Peltigera papuana
• Peltigera phyllidiosa
• Peltigera polydactylon
• Peltigera ponojensis
• Peltigera praetextata
• Peltigera retifoveata
• Peltigera rufescens
• Peltigera scabrosa
• Peltigera scabrosella
• Peltigera sumatrana
• Peltigera ulcerata
• Peltigera venosa
• Peltigera weberi

Uses

Peltigera species has been used historically to treat wounds, urinary disorders, thrush, tuberculosis, and rabies. P. apthosa was used as a remedy for cough and infantile aphthae. 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 thalli 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 prefers to eat Peltigera species (such as P. praetextata) lacking in secondary metabolites.

Bioactive compounds

Peltigera leucophlebia contains the compounds tenuiorin and methyl orsellinate, which are inhibitory 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.

Gallery

• Apfelflechte Peltigera aphtosa OhWeh-005.jpg

  Peltigera aphthosa

• Peltigera collina-3.jpg

  Peltigera collina

• Peltigera didactyla-2.jpg

  Peltigera didactyla

• Peltigera evansiana.jpg

  Peltigera evansiana

• Peltigera horizontalis-1.jpg

  Peltigera horizontalis

• Peltigera hymenina 280208.jpg

  Peltigera hymenina

• Peltigera hymenina 280208a.jpg

  Peltigera hymenina

• Peltigera leucophlebia 300808.jpg

  Peltigera leucophlebia

• Peltigera leucophlebia 300808a.jpg

  Peltigera leucophlebia

• Peltigera malacea 109220.jpg

  Peltigera malacea

• Peltigera membranacea 78681.jpg

  Peltigera membranacea

• Peltigera polydactylon-3.jpg

  Peltigera polydactylon

• Peltigera polydactyla 2006.jpg

  Peltigera polydactylon

• Peltigera praetaxtata 210908.jpg

  Peltigera praetaxtata

• Peltigera rufescens-4.jpg

  Peltigera rufescens

• Peltigera rufescens 300308.jpg

  Peltigera rufescens

Further reading

Gilbert, O. Lichens Naturally Scottish. 2004. Scottish Natural Heritage. ISBN 1-85397-373-4