Peltigera castanea is distinguished by its foliose, leaf-like thallus that loosely attaches to its substrate . It covers up to 30cm (12in) in diameter, comprising stiff, overlapping lobes that often curl upwards. Its distinctive upper surface is chestnut-brown, turning pale bluish-grey when sheltered, and features granular soredia for vegetative reproduction, housed within irregularly shaped soralia. The lichen's densely veined lower surface transitions from white to black, with tufted rhizines that become woolly towards the centre. Compared to related species in the genus Peltigera, such as P.extenuata and P.didactyla, P.castanea has a smooth, shiny, mostly non-tomentose upper cortex, darkening veins, and flocculent, often tufted rhizines, whereas its relatives show variations in lobe concavity and surface texture, including the presence of apothecia (fruiting bodies).
Taxonomy
Peltigera castanea was scientifically described as a new species in 2003 by the lichenologists Trevor Goward, Bernard Goffinet, and Jolanta Miądlikowska. The lichen falls within the Peltigera didactyla species complex, a group known for its taxonomic challenges due to subtle morphological differences among its members. The species was officially recognised following phylogenetic studies, which identified it as a distinct monophyletic group—a unique evolutionary lineage—separate from other members of the Peltigera didactyla complex. These studies were based on DNA sequencing of the internal transcribed spacer region and the large subunit of the ribosomal RNA gene, demonstrating that P.castanea forms a distinct lineage and highlighting genetic variations unique to this species.[1]
Goward collected the type specimen of Peltigera castanea in British Columbia's Clearwater River Basin, near Philip Creek along the Battle Mountain Road at an elevation of about 1,500m (4,900ft) on 1 October 2001. The specimen grew on a moss-covered boulder in an open, sunlit forest on a south-facing hillside. The species epithetcastanea, meaning "chestnut", refers to the lichen's dark, chestnut-coloured upper surface, a trait that also inspired its vernacular name, "chestnut pelt lichen".[1]
Phylogenetically, Peltigera castanea is closely related to other species within the Peltigera didactyla complex, such as P.lambinonii and P.ulcerata. While sharing some morphological traits, P.castanea has unique genetic markers that confirm its distinct species status. The complex itself is part of a larger grouping of lichens that have been difficult to categorize due to their overlapping morphological traits and the subtleties in chemical and genetic distinctions.[1]
Description
Peltigera castanea can be differentiated from other species within its genus by several distinctive features of its thallus, a term which refers to the body of the lichen. The thallus of Peltigera castanea is foliose, meaning it is leaf-like and loosely attached to its substrate , covering areas up to 6–8cm (2+3⁄8–3+1⁄8in) across,[1] although individuals up to 30cm (12in) have been recorded.[3] The individual lobes comprising the thallus are stiff, fragile, and not much longer than they are wide, with a strong concavity or sometimes flat appearance, featuring loosely overlapping and irregularly branched patterns.[1] They are generally 1.5–3cm (0.59–1.18in) in diameter.[3] The tips of the lobes are rounded and tend to curl upwards.[1]
Closeup of tomentose lobe tip, irregularly shaped soralia, and granular soredia
The upper surface of the thallus is notable for its dark chestnut-brown colour, which becomes a pale bluish grey when sheltered. The surface is more or less shiny and smooth except for being tomentose (covered with short, soft hairs) near the lobe tips. This surface is also characterised by the presence of soredia—granular reproductive structures that help in vegetative reproduction—found in rounded to irregularly shaped soralia (structures that house the soredia).[1]
The lower surface of the lichen is densely veined , gradually shifting from white at the edges to brown or black near the centre. The rhizines (root-like structures underneath the lichen) are abundant, tufted, and become flocculent (woolly) towards the centre of the thallus, matching the colour of the veins.[1] They are up to about 1cm (0.39in) long, and although usually unbranched, they are often split at the tips.[3]
In contrast, closely related species such as Peltigera praetextata have a smoother, more uniformly grey thallus with less prominent veining on the lower surface and a lack of strong colour contrast. Another similar species, Peltigera leucophlebia, has a broader thallus with a predominantly greenish hue and larger, more dispersed soralia.[1]
The absence of apothecia (fruiting bodies) and the presence of frequent, marginal pycnidia (structures that produce asexual spores) containing ellipsoid pycnoconidia (asexual spores) further help in distinguishing Peltigera castanea from its congeners. These traits, combined with its unique colouration and texture, make Peltigera castanea a distinct species within its habitat.[1] Like all Peltigera species, the photobiont of the lichen is cyanobacterial, visible as a dull bluish layer in the thallus. All of the standard chemical spot tests are negative in P.castanea, and no secondary metabolites (lichen products) have been detected using thin-layer chromatography.[4]
Several species within the genus Peltigera genus resemble Peltigera castanea, yet they have distinctive morphological traits that aid in their identification. Peltigera castanea is known for its spreading lobes with a smooth, shiny, chestnut brown, mostly non-tomentose upper cortex. The veins darken and the flocculent rhizines are often tufted and form hedgerow-like structures. This species lacks apothecia but frequently features marginal pycnidia.[1]
Close in resemblance, Peltigera extenuata has flatter lobes with a duller, densely tomentose and minutely scabrid (crusty and rough) upper cortex that varies in colour from bluish grey to purplish brown when exposed to sunlight. Unlike P.castanea, the veins and rhizines in P.extenuata are typically pale, offering a stark contrast to the darkening veins seen in P.castanea.[1]
Peltigera ulcerata is distinguished from P.castanea by its shiny upper surface, which remains non-tomentose, including at the margins of the lobes, and by its generally elongated soralia.[4]
Another species, Peltigera didactyla, also shares some similarities with P.castanea, particularly in terms of the potential shininess of the upper cortex. However, fertile specimens of P.didactyla are easily identifiable by the presence of a thick tomentum covering the upper surface and the occurrence of apothecia. Sterile specimens (i.e., those lacking apothecia) require more careful distinction, characterised by a more pouch-like habit and predominantly discrete, non-flocculent rhizines. Unlike P.castanea, the cortex of P.didactyla tends to have a predominantly purplish brown hue, distinct from the chestnut tone of P.castanea.[1]
Habitat, distribution, and ecology
The thallus lobes of P. castanea, nestled among moss, show its typical habitat over a moss mat.
Peltigera castanea predominantly inhabits mountainous forests and alpine heaths, typically growing in open, south-facing outcrops with ideal microclimate conditions. It is often found growing on xerophytic moss mats, suggesting an affinity for drier, well-drained habitats.[1] It has also been recorded growing directly on soil, rotten logs, or on soil or moss on top of rock.[3] In Estonian alvar communities, it is commonly found with mosses such as Abietinella abietina, Bryum argentatum, Ceratodon purpureus, and Tortula ruralis, sharing its habitat with several rare, ground-dwelling lichens of arcto-alpine distribution.[5]
Originally known only from northwestern North America,[1]Peltigera castanea's range includes terricolous and muscicolous growth on rock outcrops from Alaska's Chilkoot Trail to Glacier Bay,[6] extending east to the Yukon and south to Alberta's Rocky Mountains. It tends to become rare in the southern parts of its North American distribution.[3] Subsequent research has revealed its presence as far northeast as Greenland and even the Antarctic Peninsula, marking the species' adaptability to a wide range of cold environments.[7][4]
It also occurs in Russia and Estonia.[5][8] In 2023, the species was documented in Mount Xiaowutai, Hebei, China,[9] and its 2020 discovery on James Ross Island in the Antarctic Peninsula marked the first record of the lichen in the Southern Hemisphere. It is one of eight Peltigera species that are known to occur in the Antarctic.[4]
Conservation
The conservation status of Peltigera castanea varies by region. In British Columbia, it is critically imperiled with an "S1" status and is listed as "red" on the B.C. List, indicating it is a candidate for Extirpated, Endangered, or Threatened status. However, the Committee on the Status of Endangered Wildlife in Canada has not yet assessed it.[10] In Alberta, the species is classified as "SU," denoting that it is unrankable due to insufficient information, while in the Yukon, it ranges from critically imperiled to imperiled ("S1S2").[11]
In Estonia, the 2019 red list categorises Peltigera castanea as critically endangered. This designation is due to significant habitat degradation that has reduced its geographical range and habitat quality, along with its very small or restricted population size, which makes it highly vulnerable to extinction.[12]
Related Research Articles
Peltigera is a genus of approximately 100 species of foliose lichens in the family Peltigeraceae. Commonly known as the dog or pelt lichens, species of Peltigera are often terricolous, but can also occur on moss, trees, rocks, and many other substrates in many parts of the world.
Hypotrachyna lueckingii is a species of corticolous (bark-dwelling), foliose lichen in the family Parmeliaceae. It is only known to occur at high elevations on the Cordillera de Talamanca in Costa Rica.
Peltigera vainioi is a species of lichen in the family Peltigeraceae. It is found in high-elevation locations in South America. It is a somewhat unusual species in its genus, characterized by a single holdfast that attaches to its substrate, and pores in its cortex.
Punctelia bolliana, the eastern speckled shield lichen, is a species of foliose lichen in the family Parmeliaceae. It is found in North America, with a distribution extending from the Canadian province of Ontario south to the central and northeastern United States and Mexico. It grows on the bark of both deciduous trees and coniferous trees. The combination of characteristics that distinguishes this species from others in genus Punctelia are the absence of the vegetative propagules isidia and soralia, a pale brown lower thallus surface, and the presence of the secondary chemical protolichesterinic acid in the medulla.
Parmelia barrenoae is a species of foliose lichen in the large family Parmeliaceae. It was formally described as a new species in 2005. Before this, it was lumped together as one of several lichens in the Parmelia sulcata group—a species complex of genetically distinct lookalikes. Parmelia barrenoae is widely distributed, occurring in Europe, western North America, Africa, and Asia.
Parmelia fraudans is a species of foliose lichen in the family Parmeliaceae. It is found in Europe and North America, where it grows on rocks.
Peltigera papuana is a lichen-forming fungus in the family Peltigeraceae. It was described in 2009 from Madang Province of Papua New Guinea, which inspired its specific epithet. Genetic analysis of both the mycobiont and the photobiont, which is a Nostoc cyanobacterium, suggests that the evolutionary origin of Pelitgera papuana is from an ancient dispersal event from South America, although this remains inconclusive.
Peltigera wulingensis is a species of terricolous (ground-dwelling), foliose lichen in the family Peltigeraceae. Originally described from specimens found in northern China, it has since been recorded in Canada, Norway, and Russia.
Parmotrema erectociliatum is a rare species of saxicolous (rock-dwelling), foliose lichen in the family Parmeliaceae. Found on the Galápagos Islands, it was formally described as a new species in 2019 by lichenologists Frank Bungartz and Adriano Spielmann. The type specimen was collected from Santa Cruz Island near Academy Bay, where it was found growing on a boulder on a talus slope under a ravine. It is only known from the type specimen. The species epithet refers to its long, erect cilia.
Parmotrema marcellianum is a species of saxicolous (rock-dwelling), foliose lichen in the family Parmeliaceae. Found on the Galápagos Islands, it was formally described as a new species in 2019 by lichenologists Frank Bungartz and Adriano Spielmann. The type specimen was collected from Cerro Ventanas on Floreana Island at an altitude of 424 m (1,391 ft); there, it was found overgrowing pebbles on sun-, wind-, and rain-exposed ground. The species epithet honours the authors' colleague Marcelo Pinto Marcelli, "in recognition of his work on the lichen family Parmeliaceae".
Peltigera fimbriata is a species of foliose lichen in the family Peltigeraceae. Found in Papua New Guinea, it was formally described as a new species in 2009 by lichenologists Orvo Vitikainen, Emmanuël Sérusiaux, Bernard Goffinet, and Jolanta Miądlikowska. The type specimen was collected between Mt. Sarawaket Southern Range and Iloko village The species epithet fimbriata refers to the characteristic long hairs that occur on the upper thallus surface.
Peltigera granulosa is a species of terricolous (ground-dwelling), foliose lichen in the family Peltigeraceae. Found in Papua New Guinea, it was formally described as a new species in 2009 by Emmanuël Sérusiaux, Bernard Goffinet, Jolanta Miądlikowska, and Orvo Vitikainen. The type specimen was collected from open grassland between Gumum and Sape villages, where it was found growing on sand. The species epithet granulosa refers to its characteristic granulose margin.
Peltigera koponenii is a species of foliose lichen in the family Peltigeraceae. Found in Papua New Guinea, it was formally described as a new species in 2009 by Emmanuël Sérusiaux, Bernard Goffinet, Jolanta Miądlikowska, and Orvo Vitikainen. The type specimen was collected near Lake Wanba at an altitude of 2,400–2,500 m (7,900–8,200 ft), where it was found growing on a tree trunk in an open montane forest of Nothofagus and Pandanus. The species epithet honours Finnish bryologist Timo Koponen, "who made large and well processed collections of Peltigera in Papua New Guinea".
Peltigera montis-wilhelmii is a rare species of corticolous (bark-dwelling), foliose lichen in the family Peltigeraceae. Found in Papua New Guinea, it was formally described as a new species in 2009 by Emmanuël Sérusiaux, Bernard Goffinet, Jolanta Miądlikowska, and Orvo Vitikainen. The type specimen was collected from Pindaunde valley on Mount Wilhelm at an altitude of 3,600 m (11,800 ft). The species epithet refers to the type locality.
Peltigera weberi is a rare species of foliose lichen in the family Peltigeraceae. It is found in Papua New Guinea, where it grows on road banks and on earth and rock debris.
Peltigera hydrophila is a species of foliose lichen in the family Peltigeraceae. First described in 2020, it distinguishes itself through a distinct, hairless thallus that turns deep blue-violet when it becomes wet. Found primarily in the Magallanes Region of Chile, this small leafy lichen clings closely to mosses and other substrates. Distinctive features include the always-present reddish-brown to dark brown apothecia and the Peltigera-type ascospores that contain three internal partitions, or septa. Despite sharing a habitat with similar species like P. aubertii and P. frigida, P. hydrophila sets itself apart through its unique thallus surface texture and colour. This semi-aquatic lichen primarily thrives in humid forests, shrubby and herbaceous vegetation in southern Chile, particularly near waterfalls, streams, and other wet environments.
Peltigera cinnamomea, commonly known as the cinnamon-pelt lichen, is a muscicolous (moss-dwelling), leafy lichen in the family Peltigeraceae. The Canadian lichenologist Trevor Goward formally described the species in 1995. The lichen is found in northwestern North America's forested regions, particularly in the unique montane and subalpine forest communities of the northern Rocky Mountains. Peltigera cinnamomea grows under prolonged snow cover, surviving well into spring. This trait distinguishes it from many other Peltigera species in similar North American forest ecosystems.
Peltigera alkalicola is a rare species of terricolous (ground-dwelling) foliose lichen in the family Peltigeraceae. First described in 2022 from specimens collected in the Kilimanjaro National Park in Tanzania, it is characterised by its unique ecological preferences. Analysis of DNA samples indicate that the lichen may also occur in Alaska, USA, and Ningxia, China, suggesting a wider distribution in cold, montane ecosystems.
Peltigera retifoveata is a species of foliose lichen in the family Peltigeraceae. It is found in Scandinavia, western Eurasia and western North America, where it grows on the ground and amongst mosses.
Sticta torii is a rare species of corticolous (bark-dwelling), lichen in the family Peltigeraceae. Found in northwestern North America, it was formally described as a new species in 2018 by the lichenologists Antoine Simon and Trevor Goward, from specimens collected in Alaska. The species epithet honours the Norwegian lichenologist Tor Tønsberg, "in recognition of his outstanding, vigorous contribution to lichenology".
References
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Goffinet, Bernard; Miadlikowska, Jolanta; Goward, Trevor (2003). "Phylogenetic inferences based on nrDNA sequences support five morphospecies within the Peltigera didactyla complex (lichenized Ascomycota)". The Bryologist. 106 (3): 349–364. doi:10.1639/01.
↑ Zhang, Hao; Guo, Shou-yu; Han, Liu-Fu (2023). "A newly recorded species of the lichen genus Peltigera from China: Peltigera castanea". Acta Botanica Boreali-Occidentalia Sinica. 43 (6): 1063–1067. doi:10.7606/j.issn.1000-4025.2023.06.1063.
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