Dictyonema metallicum

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Dictyonema metallicum
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Basidiomycota
Class: Agaricomycetes
Order: Agaricales
Family: Hygrophoraceae
Genus: Dictyonema
Species:
D. metallicum
Binomial name
Dictyonema metallicum
Lücking, Dal-Forno & Lawrey (2013)

Dictyonema metallicum is a species of basidiolichen in the family Hygrophoraceae. [1] It is found in the montane rainforests of Ecuador. Characterised by its metallic shimmer, it is an epiphytic lichen that spans large areas on host tree trunks and frequently extends to adjacent bryophytes. Its unique visual texture is created by the loosely interwoven dark blue fibrils of the thallus, a thin, compressed filamentous layer, accentuated by a silver prothallus.

Contents

Taxonomy

Dictyonema metallicum was first scientifically described by lichenologists Robert Lücking, Manuela Dal-Forno, and James D. Lawrey. The species name metallicum signifies the distinct metallic shimmer of the thallus, observed in dry conditions. The type specimen was discovered by the first author in the Río Guajalito Protected Forest (Pichincha Province), at an altitude of 1,800 m (5,900 ft). [2]

Description

The growth pattern of D. metallicum is epiphytic, covering large areas of the host tree trunks and often extending to nearby bryophytes. The thallus – the vegetative tissue of lichens – has a thin, compressed, and appressed filamentous texture, forming patches varying from 1–5 cm (0.4–2.0 in) in size. The dark blue fibrils of the thallus, loosely interwoven, form an unusual visual texture, while a silvery prothallus outlining the thallus contributes to a strong metallic shimmer. [2]

A cross-section of the thallus measures 25–50  μm in thickness, primarily made up of an irregular photobiont layer . This layer consists of numerous cyanobacterial filaments, encased in a hyphal sheath, presenting a dark aeruginous blue. The constituent cells measure 10–13 μm in width and 4–6 μm in height. A detailed chemical analysis did not detect the presence of any substances through thin-layer chromatography. [2]

Habitat and distribution

Dictyonema metallicum has been found exclusively in the montane rainforest of Ecuador thus far, particularly flourishing in the understory on shaded tree trunks. The lichen does not limit its growth to tree trunks; it has also been observed overgrowing nearby epiphytic bryophytes. [2]

Similar species

Dictyonema metallicum shares similarities with the recently described D. hernandezii , particularly in the manner of their fibrils embedded in a gelatinous matrix. However, D. hernandezii possesses a thicker thallus with a more greenish photobiont colouration, distinguishing it from D. metallicum. The tiny fibrils of D. metallicum remind some observers of Cyphellostereum phyllogenum and C. nitidum , but these species do not possess the distinct hyphal sheath of D. metallicum, nor do they exhibit haustoria. [2] Dictyonema applanatum is another species with a similar morphology to that of D. metallicum. However, D. applanatum has fibrils of a lighter, aeruginous hue and a thallus structure that is not as densely packed, and it lacks the distinct metallic sheen of D. metallicum. Despite morphological similarities, the two species are not closely connected in terms of phylogeny. [3]

Related Research Articles

<i>Cyphellostereum</i> Genus of fungi

Cyphellostereum is a genus of basidiolichens. Species produce white, somewhat cup-shaped fruit bodies on a thin film of green on soil which is the thallus. All Cyphellostereum species have nonamyloid spores and tissues, lack clamp connections, and also lack hymenial cystidia.

Dictyonema is a genus of mainly tropical basidiolichens in the family Hygrophoraceae.

Dictyonema hernandezii is a species of basidiolichen in the family Hygrophoraceae. Found in montane rainforests of Costa Rica and in Colombia, it was described as new to science in 2011. The specific epithet hernandezii honours Venezuelan lichenologist Jesús Hernández.

Cora hirsuta is a species of basidiolichen in the family Hygrophoraceae. Found in the páramo region near Bogotá at over 3,000 m (9,800 ft) elevation, it was described as new to science in 2011. The lichen, characterised by its distinctively hairy upper surface and smaller lobes, thrives in a variety of habitats, including soil, bryophytes, and as epiphytes on trees.

Cora arachnoidea is a species of basidiolichen in the family Hygrophoraceae. Found in Venezuela, it was formally described as a new species in 2013 by Jesús Hernández and Robert Lücking. The type specimen was collected in the surroundings of Laguna de Mucubají, at an altitude of 3,626 m (11,896 ft). The specific epithet makes reference to the arachnoid (cobwebby) texture of the thallus surface. Another member of the genus with a similar surface is Cora hirsuta.

Cora byssoidea is a species of basidiolichen in the family Hygrophoraceae. Found in Colombia, it was formally described as a new species in 2013 by lichenologists Robert Lücking and Bibiana Moncada. The type specimen was collected in Páramo El Verjón at an altitude of 3,200 m (10,500 ft). Here it was found growing as an epiphyte on twigs and small branches of páramo vegetation. The lichen is only known from the type locality. The specific epithet byssoidea refers to the byssoid surface of the upper thallus. This surface comprises an irregularly dissolved layer of single hyphae in the cortex. A lookalike species, Cora hirsuta, also found at the same location, has a similar surface texture. In this lichen the surface is made of erect trichomes of agglutinated hyphae; despite their similarities, the two species are not closely related.

Cora cyphellifera is a species of basidiolichen in the family Hygrophoraceae. Found in northern Ecuador, it was formally described as a new species in 2013 by Manuela Dal-Forno, Frank Bungartz, and Robert Lücking. The type specimen was collected near the entrance to the Alto Choco Reserve at an elevation of 2,053 m (6,736 ft). Here, in open, disturbed forest patches, the lichen grows as an epiphyte on tree branches and twigs, forming foliose, light bluish-green thalli up to 15 cm (6 in) across, and comprising 20 to 30 semicircular lobes in each thallus. Cora cyphellifera is only known to occur at the type locality, which is a montane rainforest. The specific epithet refers to the unusual cyphelloid structure of the thallus; this characteristic is otherwise unknown in the genus Cora. According to the authors, "it almost looks like the lichenized thallus is parasitized by a non-lichenized, cyphelloid mushroom".

Cora inversa is a species of basidiolichen in the family Hygrophoraceae. Found in Colombia, it was formally described as a new species in 2013 by lichenologists Robert Lücking and Bibiana Moncada. The type specimen was collected in the Páramo El Verjón at an altitude of 3,200 m (10,500 ft). Here the lichen grows as an epiphyte, typically at the base of páramo shrubs, and often between bryophytes. The specific epithet refers to the partially strigose underside, presenting in an inverse fashion compared to Cora hirsuta, which is strigose on the upper side.

Cora squamiformis is a species of basidiolichen in the family Hygrophoraceae. Found in the high Andes of South America, it was formally described as a new species in 2013 by Karina Wilk, Robert Lücking, and Alba Yánez-Ayabaca. The type specimen was collected in Madidi National Park at an altitude of 4,677 m (15,344 ft). The lichen occurs in Bolivia and Ecuador, where it grows on the ground between bryophytes amongst high-mountain vegetation. It forms olive-grey to grey thalli up to 3 cm (1.2 in) across, each typically comprising 3 to 5 semicircular lobes. The specific epithet squamiformis refers to the squamulose (scaley) appearance of the thallus. A close relative, Cora pavonia, occurs in the same habitat in Ecuador; it has much larger thalli and a different lobe configuration than C. squamiformis.

Cora strigosa is a species of basidiolichen in the family Hygrophoraceae. Found in Peru, it was formally described as a new species in 2013 by Robert Lücking, Elias Paz, and Luis Salcedo. The type specimen was collected in Piscacucho at an altitude of about 2,700 m (8,900 ft). Here, in montane rainforest and pasture near Machu Picchu, the lichen grows on rocks together with other lichens, such as Hypotrachyna and Rimelia. Cora strigosa is only known to occur at the type locality. The specific epithet strigosa refers to the strigose upper surface of the thallus, especially prominent where they project radially at the margins. This lichen resembles Cora hirsuta, but it is not closely related.

Acantholichen pannarioides is a species of basidiolichen in the family Hygrophoraceae, and the type species of genus Acantholichen. The lichen has a bluish-tinged, gelatinous thallus with a surface texture that has a powdery to hairy texture. It is found in montane regions of Central America and northern South America, where it grows on forest litter, bark, on bryophytes, and on other lichens.

Dictyonema barbatum is a species of basidiolichen in the family Hygrophoraceae. It is endemic to the Galápagos Islands, where it grows as an epiphyte on the bark of branches and trunks, often on introduced plants such as avocado and guava trees. It was formally described as a new species in 2017 by Manuela Dal-Forno, Frank Bungartz, and Robert Lücking. The type specimen was collected near the southern crater rim of the Sierra Negra, at an altitude of 1,055 m (3,461 ft). Its preferred habitat is open areas with lots of rainfall and light exposure. The lichen forms shelf-like, filamentous brackets comprising individual semicircular lobes up to 8 cm (3 in) wide. The specific epithet barbatum refers to the "beard-like" white hairs on the shelf margins, a characteristic feature of this species. These "hairs" are sheaths of fungal hyphae that lack photobiont filaments.

Dictyonema darwinianum is a species of basidiolichen in the family Hygrophoraceae. It is endemic to the Galápagos Islands, where it grows as an epiphyte on the bark of branches and trunks, often closely associated with or overgrowing bryophytes and interspersed detritus. It was formally described as a new species in 2017 by Manuela Dal-Forno, Frank Bungartz, and Robert Lücking. The type specimen was collected along the trail from Bellavista to El Puntudo on Santa Cruz Island at an altitude of 502 m (1,647 ft). The lichen is common and widespread on the Galápagos Islands, where it forms dark bluish-green filamentous and crust-like mats on Frullania liverworts and associated forest detritus. The specific epithet darwinianum honours Charles Darwin and the Charles Darwin Foundation.

Dictyonema lawreyi is a species of basidiolichen in the family Hygrophoraceae. Found in the United States, it was formally described as a new species in 2019 by Manuela Dal Forno, Laurel Kaminsky, and Robert Lücking. The type specimen was collected in Ocala National Forest, where it was growing as an epiphyte on a trunk of Magnolia. It is only known to occur here and in two other locations in Florida, all in hardwood forests. The lichen has a crustose and filamentous growth form on a white hypothallus, and thallus surface made of a mat of turquoise, loosely interwoven fibrils forming more or less continuous patches up to 5 cm (2 in) long. The type was collected by lichenologist James D. Lawrey, for whom the species is named, and whose work, according to the authors, "helped to redefine the circumscription of the genus Dictyonema s.str."

Dictyonema subobscuratum is a species of basidiolichen in the family Hygrophoraceae. It is endemic to the Galápagos Islands, where it mostly grows as an epiphyte over bryophytes on branches and trunks in humid zones. It was formally described as a new species in 2017 by Manuela Dal-Forno, Frank Bungartz, and Robert Lücking. The type specimen was collected on Floreana Island along the rim trail to Cerro Pajas at an altitude of 442 m (1,450 ft); it has also been recorded from Santa Cruz Island. The lichen forms dark bluish-green filamentous, irregular mats that grow in patches up to 5 cm (2.0 in) across. The specific epithet subobscuratum refers to its similarity with Dictyonema obscuratum, found in Brazil.

Dictyonema album is a species of basidiolichen in the family Hygrophoraceae. It is found in Mauritius, where it grows as an epiphyte on shrubs.

Dictyonema ramificans is a basidiolichen species in the family Hygrophoraceae. Discovered in 2010 in the Galapagos Islands, it was formally described as a new species in 2017 by lichenologists Manuela Dal-Forno, Alba Yanez-Ayabaca, and Robert Lücking. Its species epithet is derived from the branching pattern of the fibrils that form a net-like structure, giving it an arachnoid (cobweb-like) appearance. This species has only been found in the humid zone of Santa Cruz Island, growing exclusively on bryophytes. While it is similar to other Dictyonema species, it differs in its unique fibril branching pattern and erect arachnoid structure.

Dictyonema aeruginosulum is a species of basidiolichen in the family Hygrophoraceae. Characteristics of the lichen include its distinctive finger-like projections and blue-green hue. It is distinguishable from its closest relatives by its unique morphology and the absence of clamp connections in its structure. Dictyonema aeruginosulum is an epiphyte, forming thick mats on tree trunks within rainforest regions. The species was first identified in Costa Rica's Tenorio Volcano National Park, and it has only been recorded from this location.

Dictyonema krogiae is a species of basidiolichen in the family Hygrophoraceae. It is found in Kenya, where it grows as an epiphyte on trees. It is often found in association with other lichens, such as Parmotrema, and bryophytes, such as Frullania. A main characteristic that distinguishes it from other closely related species is its clearly defined internal layers, including its contrasting dense photobiont layer and a loose lower cortex.

Dictyonema obscuratum is a species of basidiolichen in the family Hygrophoraceae. Originally discovered in Brazil and later recorded in Bolivia and Colombia, its cryptic, olive-green thallus sets it apart from similar species like Dictyonema phyllophilum and D. schenckianum.

References

  1. "Dictyonema metallicum Lücking, Dal-Forno & Lawrey". Catalogue of Life . Species 2000: Leiden, the Netherlands. Retrieved 11 June 2023.
  2. 1 2 3 4 5 Lücking, Robert; Dal-Forno, Manuela; Lawrey, James D.; Bungartz, Frank; Rojas, María E. Holgado; Hernández M., Jesús E.; Marcelli, Marcelo P.; Moncada, Bibiana; Morales, Eduardo A.; Nelsen, Matthew P.; Paz, Elias; Salcedo, Luis; Spielmann, Adriano A.; Wilk, Karina; Will-Wolf, Susan; Yánez-Ayabaca, Alba (2013). "Ten new species of lichenized Basidiomycota in the genera Dictyonema and Cora (Agaricales: Hygrophoraceae), with a key to all accepted genera and species in the Dictyonema clade". Phytotaxa. 139 (1): 1–38. doi:10.11646/phytotaxa.139.1.1.
  3. Lücking, Robert; Dal-Forno, Manuela; Wilk, Karina; Lawrey, James D. (2013). "Three new species of Dictyonema (lichenized Basidiomycota: Hygrophoraceae) from Bolivia". Acta Nova. 6 (1–2).