Placidium arboreum

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Placidium arboreum
Placidium arboreum (4751215902).jpg
In the Great Smoky Mountains of North Carolina (southeastern United States)
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Eurotiomycetes
Order: Verrucariales
Family: Verrucariaceae
Genus: Placidium
Species:
P. arboreum
Binomial name
Placidium arboreum
(Schwein. ex E.Michener) Lendemer (2004)
Synonyms [1] [2]
List
  • Endocarpon arboreumSchwein. (1831)
  • Endocarpon arboreumSchwein. ex E.Michener (1853)
  • Dermatocarpon arboreum(Schwein. ex E.Michener) Fink (1910)
  • Endocarpon tuckermanii Ravenel ex Mont. (1856)
  • Endopyrenium tuckermanii(Ravenel ex Mont.) Müll.Arg. (1884)
  • Dermatocarpon tuckermanii(Ravenel ex Mont.) Zahlbr. (1921)
  • Catapyrenium tuckermanii(Ravenel ex Mont.) J.W.Thomson (1987)
  • Placidium tuckermanii(Ravenel ex Mont.) Breuss (1996)

Placidium arboreum, commonly known as the tree stipplescale, is a species of corticolous (bark-dwelling), squamulose (scaley) lichen in the family Verrucariaceae. Placidium arboreum is primarily found in the southeastern United States, but it also has occurrences in the western and northeastern United States, Mexico, the West Indies, Argentina, and Ontario, Canada. In its habitat, it typically grows at the base of hardwood trees, particularly oak species, and can occasionally be found on other tree genera or even over mosses on limestone. Its preferred substrate is the bark of oak trees, and the lichen usually establishes itself in bark crevices.

Contents

Originally described as Endocarpon arboreum in 1831, Placidium arboreum underwent various taxonomic changes before acquiring its current generic placement in 2004. Some authors had referred to it as Endocarpon tuckermanii, but the name with the species epithet tuckermanii is now considered synonymous.

Taxonomy

The lichen was first mentioned in the scientific literature as Endocarpon arboreum in an 1831 publication of Swedish botanist and mycologist Elias Fries, who attributed authorship to German-American botanist and mycologist Lewis David de Schweinitz. [3] Fries wrote of the lichen: "In addition there is a variety, Endocarpon arboreum of Schweinitz from North America, which by its description should be referred here but from its whole structure seems to be a poorly developed Sticta ". Fries does not seem to have accepted it as a valid species. [4] Further, because no description or diagnosis of the taxon was provided (i.e., as a nomen nudum , or "naked name"), the name was not validly published according to nomenclatural rules. [5] American botanist Ezra Michener published the taxon validly when he included a brief description of the species in American botanist William Darlington's 1853 work Flora Cestrica. [6] American lichenologist Bruce Fink proposed a transfer to the genus Dermatocarpon in 1910. [7] The taxon acquired its current generic placement when American lichenologist James Lendemer transferred it to Placidium in 2004. [2] Molecular phylogenetics reveals that Placidium arboreum is sister to a clade of Placidium species characterized by cylindrical asci in their early developmental stages. [8]

According to Lendemer, some later authors have used the specific epithet tuckermanii for this species (Endocarpon tuckermaniiRavenel ex Mont. was validly published by Camille Montagne in 1856). [2] This was because in 1956, American lichenologist Mason Hale designated the name Endocarpon arboreum as a nomen nudum, which opened the way to use the epithet tuckermanii; he was apparently not aware of Michener's publication. [9] Since Michener's description of the species was published earlier than Montagne's, it has priority, and those names (and later recombinations) with epithet tuckermanii are relegated to synonymy. [2]

Lichens in the genus Placidium are generally known in the vernacular as "stipplescale lichens"; the specific common name used for this species is "tree stipplescale". [10] Placidium arboreum belongs to the catapyrenioid group within the Verrucariaceae, characterized by over 80 lichens that are squamulose (scaley), possess simple ascospores (devoid of septa), and do not contain algae in the hymenium. [11]

Description

Placidium arboreum becomes green when wet. Tree Stipplescale (4752735810).jpg
Placidium arboreum becomes green when wet.

It has a squamulose (scaly) thallus comprising individual rounded lobes typically measuring 2–5 mm (1⁄16–3⁄16 in) wide, [10] although squamule widths of up to 10 mm (3⁄8 in) are also reported. These are relatively large, more or less overlapping squamules. [12] In a field guide to lichens of Great Smoky Mountains National Park, the authors highlight the distinctiveness of the species due to its uniquely large squamules. This characteristic makes it stand out, and in this region, it is rarely mistaken for other species. [13] The lichen is normally shades of brown and grey, but becomes bright green when wet. The medulla is white. [12]

Dark brown, dot-like perithecia are scattered on the thallus surface. The underside of the thallus is paler in colour, with tufts of rhizohyphae that attach to the substrata . All of the standard chemical spot tests are negative, [10] and it does not have any known lichen products. [12] The ascospores made by the lichen are ellipsoid in shape, with dimensions of 10–15 by 4–6  μm. [4] The photobiont partner of the lichen is chlorococcoid – a green alga from genus Chlorococcum . [12]

Similar species

Catapyrenium cinereum is another squamulose lichen that bears a resemblance to Placidium arboreum. Several distinctions can be observed in Catapyrenium cinereum – its brown to black rhizohyphae, the formation of a thick, dark hypothallus , a typically densely pruinose upper surface, and clavate (club-shaped) asci. Although some species from the genus Clavascidium may appear similar, they are characterized by specific rhizines and/or clavate asci. [12]

Habitat and distribution

Placidium arboreum is widely distributed in the southeastern United States, with a few scattered occurrences in the western and northeastern United States. [10] It is rare in California, with some reports from locations in the Coast Range. [14] The North American range of the lichen extends south to Mexico. The lichen has also been found in the West Indies and has been recorded in Tucumán, Argentina, where it was growing in a rainforest at an elevation of 1,200 m (3,900 ft). [4] In 2017, it was recorded for the first time in Canada after it was found in a few locations in Ontario; [15] it is considered an uncommon species in this province. [12]

The lichen typically grows at the base of hardwood trees, and the bark of oak is a preferred substratum. [10] Placidium arboreum has been recorded on several oak species: Quercus alba (white oak) is a predominant associate in the northern part of its range, Q. stellata (post oak) and Q. muehlenbergii (chinkapin) occur further south, while Q. virginiana (southern live oak), Q. arizonica (Arizona white oak), and Q. douglasii (blue oak) are associated with the lichen in the south and southwest parts of its range. Tree genera that associate with Placidium arboreum less commonly include Ulmus (elm), Fraxinus (ash), Carya (hickory), Platanus , Liquidambar (sweetgum), Acer (maple), and Salix (willow). [4] The lichen generally establishes itself in the crevices of the bark. [13] In rare instances, it has been recorded growing over mosses on limestone. [4]

Related Research Articles

<span class="mw-page-title-main">Verrucariaceae</span> Family of mostly lichenised fungi

Verrucariaceae is a family of lichens and a few non-lichenised fungi in the order Verrucariales. The lichens have a wide variety of thallus forms, from crustose (crust-like) to foliose (bushy) and squamulose (scaly). Most of them grow on land, some in freshwater and a few in the sea. Many are free-living but there are some species that are parasites on other lichens, while one marine species always lives together with a leafy green alga.

Clavascidium is a genus of lichens in the family Verrucariaceae. The genus was circumscribed in 1996 by Austrian lichenologist Othmar Breuss. Because the type species of the genus, Clavascidium umbrinum, has been shown using molecular phylogenetics to belong to genus Placidium, Cécile Gueidan and colleagues proposed to unite Clavascidium with Placidium in a 2009 publication. Despite this, the genus has been retained in recent publications of fungal classification.

<i>Placidium</i> Genus of lichens

Placidium is a genus of crustose to squamulose to almost foliose lichens. The genus is in the family Verrucariaceae. Most members grow on soil, but some grow on rock (saxicolous). The fruiting bodies are perithecia, flask-like structures immersed in the lichen body (thallus) with only the top opening visible, dotting the thallus. Lichen spot tests are all negative. Members of the genus lack rhizines, but otherwise resemble members of the genus Clavascidium.

<span class="mw-page-title-main">Lichen growth forms</span> Gross morphological classification

Lichens are symbiotic organisms made up of multiple species: a fungus, one or more photobionts and sometimes a yeast. They are regularly grouped by their external appearance – a characteristic known as their growth form. This form, which is based on the appearance of vegetative part of the lichen, varies depending on the species and the environmental conditions it faces. Those who study lichens (lichenologists) have described a dozen of these forms: areolate, byssoid, calicioid, cladoniform, crustose, filamentous, foliose, fruticose, gelatinous, leprose, placoidioid and squamulose. Traditionally, crustose (flat), foliose (leafy) and fruticose (shrubby) are considered to be the three main forms. In addition to these more formalised, traditional growth types, there are a handful of informal types named for their resemblance to the lichens of specific genera. These include alectorioid, catapyrenioid, cetrarioid, hypogymnioid, parmelioid and usneoid.

Parmeliella triptophylloides is a species of corticolous (bark-dwelling) lichen in the family Pannariaceae. Found in east Africa, it was formally described as a new species in 2003 by Norwegian lichenologist Per Magnus Jørgensen. The type specimen was collected by Dutch mycologist Rudolf Arnold Maas Geesteranus in 1949, from the Cherang'any Hills at an elevation of 900 m (3,000 ft). In addition to the type locality, it has also been recorded from the Luhangalo Plateau in Tanzania.

Candelariella corallizoides is a species of squamulose (scaley), saxicolous (rock-dwelling) lichen in the family Candelariaceae. Found in Mexico, it was formally described as a new species in 2007 by Swedish lichenologist Martin Westberg. The type specimen was collected from the north-facing cliffs of the Sierra Agua Verde at an elevation of 1,200 m (3,900 ft). Here, in open oak woodland with shrubs, it was found growing on siliceous rock. The lichen is known to occur in several localities in Baja California. The specific epithet corallizoides refers to the coralloid squamules of the thallus.

Candelariella complanata is a species of squamulose (scaley) and saxicolous (rock-dwelling) lichen in the family Candelariaceae. Found in southwestern North America, it was formally described as a new species in 2007 by Swedish lichenologist Martin Westberg. The type specimen was collected from a cliff of the Sierra Agua Verde at an elevation of about 1,000 m (3,300 ft); here it was found growing on volcanic rock. The thallus of the lichen is complanate (smooth) as a result of its flattened and peltate squamules. This gives it a distinct appearance that is referenced in the specific epithet complanata. The geographic range of Candelariella complanata includes Baja California, Coahuila, Sinaloa, and Sonora, north to southern Arizona, Texas, and New Mexico. It prefers to grow on siliceous rock in open montane habitats to elevations of at least 1,900 m (6,200 ft).

Waynea cretica is a species of corticolous (bark-dwelling), squamulose lichen in the family Ramalinaceae. It occurs on the Greek island of Crete and in Portugal.

<i>Catapyrenium boccanum</i> Species of lichen

Catapyrenium boccanum is a species of squamulose (scaley), rock-dwelling lichen in the family Verrucariaceae. It grows on mortar or on calcareous rock. Its squamules are up to 4 mm wide, pale to dark brown with black margins and a black underside. Ascospores measure 11–15 by 5–8 μm. Because of its combination of squamulose thallus, simple ascospores, and lack of algae in the hymenium, this species is a "catapyrenioid" lichen, of which more than 80 exist in the Verrucariaceae.

Clavascidium sinense is a species of squamulose (scaley), ground-dwelling lichen in the family Verrucariaceae. Found in Northwest China, it was formally described as a new species in 2022 by Tingting Zhang and Xinli Wei. The type specimen was collected in Datong City at an altitude of 1,147 m (3,763 ft). The species epithet sinense refers to its Chinese distribution.

<i>Agonimia octospora</i> Species of lichen

Agonimia octospora is a species of corticolous, (bark-dwelling) squamulose (scaly) lichen in the family Verrucariaceae. It was formally described as a new species in 1978 by the lichenologists Brian John Coppins and Peter Wilfred James. The type specimen was collected in Glengarriff Forest in (West Cork, where it was found growing on the bark of oak. Characteristics of the lichen include its colourless ascospores that number eight per ascus, and its tiny squamules that are closely attached to its substrate. Its spores typically measure 60–75 by 20–26 μm. The lichen is found in Europe and South America.

<i>Platismatia tuckermanii</i> Species of lichen

Platismatia tuckermanii is a species of corticolous (bark-dwelling), foliose lichen in the family Parmeliaceae. It is endemic to Eastern North America and is distinguished by its broad, loosely attached lobes and primarily sexual reproduction.

Krogia microphylla is a rare species of corticolous (bark-dwelling), squamulose (scaley) lichen in the family Ramalinaceae. Found in the Dominican Republic, it was formally described as a new species in 2011 by lichenologist Einar Timdal. The type specimen was collected from a cloud forest in El Seibo Province at an altitude of about 450 m (1,480 ft). It is only known from the type collection. The species epithet refers to the tiny squamules that make up the thallus.

Fuscopannaria dissecta is a species of corticolous (bark-dwelling), squamulose lichen in the family Pannariaceae. Found in Japan, it was formally described as a new species in 2000 by Norwegian lichenologist Per Magnus Jørgensen. The type specimen was collected by Syo Kurokawa from Mount Kōya at an altitude of 800 m (2,600 ft); there it was found growing on the rotting bark of trees. The lichen has a pale brown thallus that forms irregular patches comprising squamules that about are about 2 mm wide. The squamules are dissected–cut deeply into fine lobes–and it is this character that is referenced in the species epithet dissecta.

<i>Fuscopannaria leucosticta</i> Species of lichen

Fuscopannaria leucosticta, commonly known as the rimmed shingle lichen, is a species of lichen in the family Pannariaceae. It has a squamulose (scaley) thallus that lacks soredia and isidia, but has abundant apothecia with distinct white rims. Although its main centres of distribution are eastern North America and southeast Asia, where it grows in damp forests, it has been reported from various other high-altitude, humid locations.

Phlyctis monosperma is a species of corticolous (bark-dwelling), crustose lichen in the family Phlyctidaceae. It is characterised by its greyish-white, loose, granular thallus, single-spored asci, and distinctive chemical substances. The lichen is found in the subtropical evergreen forests of the Eastern Himalayas and Western Ghats of India, where it grows on rough tree bark in close association with plant-dwelling bryophytes at elevations above 2,000 m (6,600 ft). It also occurs in Sri Lanka.

<span class="mw-page-title-main">Alan Orange</span> British lichenologist (1955–2023)

Alan Orange was a British lichenologist. His research interests included lichen taxonomy and phylogenetics, aquatic lichens, and the family Verrucariaceae.

<i>Protocandelariella</i> Genus of lichens

Protocandelariella is a genus of lichen-forming fungi in the family Candelariaceae. It has two species of squamulose (scaley), corticolous (bark-dwelling) lichens.

<i>Normandina pulchella</i> Species of lichen

Normandina pulchella, commonly known as the elf-ear lichen or blue heart, is a species of squamulose lichen in the family Verrucariaceae. This cosmopolitan species is widely distributed across both hemispheres, where it thrives in moist microhabitats. It favours moss-covered deciduous trees and rocks, often colonising over mosses and bryophytes. It occasionally grows on bare bark and on other lichens. Distinctive features of N. pulchella include its bluish-green squamules (scales) with sharply raised margins, non-reactivity to standard chemical spot tests, and growth in humid habitats. Initially, Nannochloris normandinae, a green alga, was thought to be its photobiont. However, recent studies have revised this understanding, now suggesting Diplosphaera as the algal partner.

Knightiellastrum is a single-species fungal genus in the family Icmadophilaceae. This monotypic genus the contains the corticolous (bark-dwelling), squamulose lichen species Knightiellastrum eucalypti, found in Tasmania, Australia.

References

  1. ↑ "Synonymy. Current Name: Placidium arboreum (Schwein. ex E. Michener) Lendemer, in Lendemer & Yahr, Mycotaxon 90(2): 320 (2004)". Species Fungorum . Retrieved 10 July 2022.
  2. 1 2 3 4 Lendemer, James C.; Yahr, Rebecca (2004). "Changes and additions to the Checklist of North American Lichens. – II". Mycotaxon. 90 (2): 319–322.
  3. ↑ Fries, E.M. (1831). Lichenographia Europaea Reformata (in Latin). p. 407.
  4. 1 2 3 4 5 Thomson, John W. (1987). "The lichen genera Catapyrenium and Placidiopsis in North America". The Bryologist. 90 (1): 27–39. doi:10.2307/3243269. JSTOR   3243269.
  5. ↑ "Record Details: Endocarpon arboreum Schwein., in Fries, Lich. eur. reform. (Lund): 407 (1831)". Index Fungorum . Retrieved 11 July 2022.
  6. ↑ Darlington, William (1853). Flora Cestrica (3rd ed.). Philadelphia: Lindsay & Blakiston. p. 451.
  7. ↑ Fink, B. (1910). The Lichens of Minnesota. Contributions from the US National Herbarium. Vol. 14. p. 244.
  8. ↑ Prieto, María; Martínez, Isabel; Aragón, Gregorio; Gueidan, Cécile; Lutzoni, François (2012). "Molecular phylogeny of Heteroplacidium, Placidium, and related catapyrenioid genera (Verrucariaceae, lichen-forming Ascomycota)". American Journal of Botany. 99 (1): 23–35. doi: 10.3732/ajb.1100239 . PMID   22210842.
  9. ↑ Hale, Mason E. (1956). "Studies on the chemistry and distribution of North American lichens (6–9)". The Bryologist. 59 (1): 114–117. doi:10.2307/3239925. JSTOR   3239925.
  10. 1 2 3 4 5 Brodo, Irwin M.; Sharnoff, Sylvia Duran; Sharnoff, Stephen (2001). Lichens of North America. Yale University Press. pp. 570–571. ISBN   978-0300082494.
  11. ↑ Breuss, Othmar (2010). "An updated world-wide key to the catapyrenioid lichens (Verrucariaceae)". Herzogia. 23 (2): 205–216. doi:10.13158/heia.23.2.2010.205.
  12. 1 2 3 4 5 6 McMullin, R. Troy (2023). Lichens. The Macrolichens of Ontario and the Great Lakes Region of the United States. Firefly Books. p. 408. ISBN   978-0-228-10369-1.
  13. 1 2 Tripp, Erin A.; Lendemer, James C. (2020). Field Guide to the Lichens of Great Smoky Mountains National Park. Knoxville: The University of Tennessee Press. p. 369. ISBN   978-1-62190-514-1.
  14. ↑ Sharnoff, Stephen (2014). A Field Guide to California Lichens. New Haven: Yale University Press. pp. 328–329. ISBN   978-0-300-19500-2. OCLC   862053107.
  15. ↑ Lewis, Christopher J.; Brinker, Samuel R. (2017). "Notes on new and interesting lichens from Ontario, Canada – III". Opuscula Philolichenum. 16: 153–187. doi:10.5962/p.386108.
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