Serusiauxia

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Serusiauxia
Serusiauxia inexpectata.png
Holotype specimen of Serusiauxia inexpectata, showing its sorediate thallus; scale bar = 2.5 mm
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Eurotiomycetes
Order: Pyrenulales
Family: Pyrenulaceae
Genus: Serusiauxia
Ertz & Diederich (2020)
Species:
S. inexpectata
Binomial name
Serusiauxia inexpectata
Ertz & Diederich (2020)
Serusiauxia
Holotype: Sir Seewoosagur Ramgoolam Botanical Garden, Mauritius

Serusiauxia is a monotypic fungal genus in the family Pyrenulaceae. [1] It contains a single species, Serusiauxia inexpectata, a corticolous (bark-dwelling), crustose lichen found in Mauritius. Serusiauxia is morphologically distinct within the Pyrenulaceae due to its sorediate thallus and chemistry involving gyrophoric acid, a combination of characteristics that is not observed in any other Pyrenulaceae genera.

Contents

Taxonomy

Genus Serusiauxia was established by Damien Ertz and Paul Diederich in 2020 to accommodate a unique species within the family Pyrenulaceae. The type specimen was collected by Diederich from the Sir Seewoosagur Ramgoolam Botanical Garden (Pamplemousses District, Mauritius), at an elevation of 80 m (260 ft), where it was found growing on a more or less vertical trunk of a Terminalia tree. The species is characterised by its sorediate thallus and the presence of gyrophoric acid. The genus is distinguished from other genera in the Pyrenulaceae by its chemical composition, specifically the C+ (red) soralia reaction due to gyrophoric acid. [2]

The genus is named in honour of Emmanuël Sérusiaux, recognising his significant contributions to the field of lichenology, particularly in tropical regions. The species epithet inexpectata alludes to its surprising taxonomic classification within the family Pyrenulaceae, given its morphological resemblance to certain species in the order Arthoniales. [2]

Molecular phylogenetics analyses place Serusiauxia as a sister taxon to Lithothelium septemseptatum , positioned basally within a clade that includes the genus Anthracothecium and several species of Pyrenula , such as Pyrenula nitida (the type species of Pyrenula). [2] This clade corresponds to 'Pyrenulaceae, Group 1' as defined by Cécile Gueidan and colleagues in 2016. [3] The phylogenetic results suggest that Pyrenula should be divided into multiple genera. Serusiauxia and Lithothelium septemseptatum form a distinct clade, separate from Pyrenula (in the strict sense) and Anthracothecium, indicating significant genetic divergence. [2]

Description

Serusiauxia inexpectata is a crustose lichen with a thin and rather inconspicuous thallus, which primarily grows within the bark ( endophloeodal ). Its colour ranges from whitish to pale cream, with a brownish prothallus . The photobiont , the photosynthetic partner in the lichen, is trentepohlioid , featuring cells that measure between 6–11  micrometres (µm) in length and 4–8 µm in width. [2]

The lichen produces numerous soralia, which are structures that produce powdery reproductive propagules called soredia. These soralia are dense and small when young, appearing as tiny dots that eventually erupt from the thallus. They can be flat to slightly convex and contain loosely packed soredia. Over time, they can spread and merge, sometimes forming a nearly continuous crust over large areas of the thallus. The colour of the soralia varies from pale creamish brown to rarely pale greyish-almost white. [2]

The soredia lack protruding hyphae (filamentous structures of the fungus) and measure between 25 and 60 µm in diameter. The hyphae themselves are 2–2.5 µm in diameter and are covered with tiny, colourless (hyaline) crystals that dissolve in potassium hydroxide (K) solution. Calcium oxalate crystals are also present, mostly measuring 0.5–4 µm in diameter, with a few larger ones up to 12 µm. Ascomata (spore-producing structures) and conidiomata (structures producing asexual spores) have not been observed to occur in this species. [2]

Chemically, both the thallus and the soralia react with chemical spot tests: they are C+ (fleetingly red), K+ (weakly pale yellow), and do not react with P−, UV−, I−, and KI−. Thin-layer chromatography has revealed the presence of gyrophoric acid in the lichen. [2]

Similar species

Serusiauxia inexpectata can be compared to several other lichens, although key differences set it apart:

Dendrographa decolorans : This species differs by having soralia that range from mauve-grey to pale lilac-grey in colour. It also has different chemical properties, featuring unidentified fatty acids and a C− thallus. Additionally, Dendrographa decolorans is found mainly in Mediterranean and temperate regions and belongs to a different phylogenetic group (Arthoniomycetes, Roccellaceae)​​. [2]

Syncesia myrticola (sorediate morphs): This species differs chemically by containing protocetraric acid, with a thallus that reacts PD+ (rust-red). It is morphologically similar but can be distinguished by its distinct chemical reactions​​. [2]

Opegrapha fumosa : While this species also has a thin, inconspicuous thallus with C+ red soralia (due to gyrophoric acid), its soralia are less dense, more irregular, and often elliptical. Furthermore, Opegrapha fumosa is confined to temperate regions​​. [2]

Habitat and distribution

Serusiauxia inexpectata is known to occur in specific locations within Mauritius and the Seychelles. In Mauritius, it has been recorded in the Sir Seewoosagur Ramgoolam Botanical Garden and the Curepipe Botanic Gardens, where it typically grows on the bark of large trees, such as Mangifera (mango) and Terminalia species. In the Seychelles, the species has been found on the island Mahé, specifically within the 'Jardin du Roi' parkland. [2]

Related Research Articles

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Architrypethelium is a genus of lichen-forming fungi in the family Trypetheliaceae.

Bacidina sorediata is a species of foliicolous (leaf-dwelling) lichen in the family Ramalinaceae. Found in the Seychelles, it was described as new to science in 2011. It is characterized by its distinct sorediate thallus and pale yellow to orange apothecia.

Vermilacinia leonis is a fruticose lichen usually found on branches of shrubs in the fog regions along the Pacific Coast of North America and South America; in North America it is found on the southern half of the main peninsula of Baja California north to the southern coast of the Vizcaíno Peninsula. In South America, it occurs on bushes and rocks in Chile; reported from Colchaqua (Valley) and Santiago The epithet is in regard to absence of the black transverse bands often seen in other species such as V. leopardina, V. tigrina and V. zebrina.

<i>Punctelia caseana</i> Species of lichen

Punctelia caseana is a species of foliose lichen in the family Parmeliaceae. Its range covers eastern North America, extending south to central and northern Mexico, where it grows on the bark of many species of hardwood and conifer trees.

<i>Punctelia perreticulata</i> Species of lichen

Punctelia perreticulata is a widely distributed species of foliose lichen in the family Parmeliaceae. It occurs in Mediterranean Europe and Russia, North America, South America, Australia, and New Zealand, where it grows on rocks, bark, or wood. Its main distinguishing features are its thallus surface, marked with many shallow depressions, grooves, or pits, and sorediate pseudocyphellae. The lower side of the thallus is ivory to tan towards the centre and the major secondary metabolite in the medulla is lecanoric acid. A lookalike species with which it has been historically confused is Punctelia subrudecta; this lichen can be distinguished from Punctelia perreticulata by the texture of the thallus surface, or, more reliably, by the length of its conidia.

Pyrenula muriciliata is a species of corticolous (bark-dwelling) and crustose lichen in the family Pyrenulaceae. It is found in Mauritius, where it grows on tree bark in parklands and forests.

Lecania sessilisoraliata is a species of saxicolous (rock-dwelling), crustose lichen in the family Ramalinaceae. It is found on rock outcrops in the mountainous Burdur region of Turkey.

Inoderma sorediatum is a species of crustose lichen in the family Arthoniaceae. It is only known to occur on the bark of trees in Poland's Białowieża National Park. It is differentiated from other species in genus Inoderma by the form of its thallus, which is entirely made of powdery, granular soredia, as well as by the presence of a unique combination of lichen products.

Wilketalia is a fungal genus in the family Teloschistaceae. It is monotypic, containing the single species Wilketalia citrinoides, a saxicolous (rock-dwelling) crustose lichen found in the Bolivian Andes.

Opegrapha ramisorediata is a rare species of corticolous (bark-dwelling), crustose lichen in the family Opegraphaceae. Known to occur only in northeastern Brazil, it was described as a new species in 2017. It is characterised by a thin, pale greenish-mauve thallus.

Aspiciliopsis is a genus of lichen-forming fungi in the family Trapeliaceae. It has two species, both of which occur in the Southern Hemisphere.

Cratiria sorediata is a species of corticolous (bark-dwelling), crustose lichen in the family Caliciaceae. It was first described as a new species in 2009. The type specimen was collected from Aldabra in the Seychelles.

Caloplaca sterilis is a corticolous (bark-dwelling), crustose lichen belonging to the family Teloschistaceae, described in 2011. It is primarily found in steppe and sand dune habitats in the Black Sea region, and has been recorded from Bulgaria, Romania, southwest Russia, and Ukraine. Caloplaca sterilis is characterised by tiny squamules/areoles with contrasting pale greyish-green to greenish soredia. It is easily overlooked and challenging to identify when completely sorediate and sterile, especially as its soredia do not contain the typical Sedifolia-grey pigment.

Fellhanera ivoriensis is a species of foliicolous (leaf-dwelling) lichen. First described in 2001, this species is distinguished from its relatives in the Fellhanera by its soredia-covered thallus and the characteristics of its apothecia. It is native to the Ivory Coast in West Africa.

Micarea viridileprosa is a species of crustose lichen in the family Pilocarpaceae that was first described in 2001. This crustose lichen is known to grow on bark, wood, and soil, and is distinguishable by its bright greenish soredia.

Filsoniana ferdinandmuelleri is a species of saxicolous (rock-dwelling), crustose lichen in the family Teloschistaceae. It is found in Australia. The lichen has a squamulose (scaly) thallus, with a range of bright yellow to greenish-yellow and brownish-orange colours in its soredia and apothecia, respectively. The areoles of this lichen are varied in size, slightly raised from the thallus surface, and each carries one to four apothecia. The soralia are rounded or irregularly shaped, covering most of the thallus surface as a yellow to greenish-yellow mass. The apothecia have dark brownish-orange discs, surrounded by slightly paler yellow margins, with the spore-bearing asci containing typically eight brownish-golden ascospores.

Loekoesia is a genus of lichen-forming fungi in the family Teloschistaceae. It contains three species of saxicolous (rock-dwelling), crustose lichens. Collectively, the genus occurs in South Korea, Mauritius, and the United States. The genus is distinguished by its grey, crust-like thallus, which can be either whole or divided into patch-like segments. Loekoesia lichens have bright white, rounded soralia, which produce bluish to whitish powdery propagules (soredia) and are arranged in irregular groups on the thallus.

Rhizoplaca ouimetensis is a saxicolous (rock-dwelling), crustose lichen species in the family Lecanoraceae. Uniquely identified by its sorediate form—a feature not observed in other Rhizoplaca species—it was discovered in Ontario, Canada, specifically within the Ouimet Canyon Provincial Park.

<i>Xylopsora canopeorum</i> Species of lichen

Xylopsora canopeorum is a squamulose (scaly), corticolous (bark-dwelling) lichen species in the family Umbilicariaceae. Discovered in the canopies of Sequoia sempervirens in California, United States, it was formally described as new to science in 2018. It is endemic to the central coastal region of California, living within the unique ecosystems of Big Basin Redwoods State Park and Armstrong Redwoods State Natural Reserve, areas known for their ancient coast redwood forests. The lichen evolves from a crust-like to scale-like form, developing into coral-like crusts as it matures, complemented by distinctive flat, black reproductive discs. This species has varying greyish-green to medium brown coloration and occasionally forms soralia, which release powdery reproductive propagules called soredia. Xylopsora canopeorum is distinguished from closely related species by its smaller, partly coral-like squamules (scales), the occurrence of soralia on its surface, and in some specimens, the presence of both thamnolic and friesiic acids within the thallus.

<i>Mycoblastus sanguinarius</i> Species of lichen

Mycoblastus sanguinarius, commonly known as the bloody heart lichen, is a widespread species of crustose lichen in the family Tephromelataceae. It is distinguished by its pale to dark grey thallus, which can appear very irregular and uneven, often with a thick, coarse, wart-like texture. The thallus may be continuous or somewhat cracked, with a prothallus that ranges from pale to dark grey. The apothecia are frequent, black, and become convex or hemispherical as they mature. These structures develop on a bright carmine-red thalline cushion, which is revealed when the thallus is damaged or worn. The lichen grows in temperate and montane forests across Asia, Europe, and North America. Usually found on tree bark, it has been recorded less frequently on decorticated wood and moss-covered rocks.

References

  1. "Serusiauxia". Catalogue of Life . Species 2000: Leiden, the Netherlands. Retrieved 23 June 2024.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 Diederich, Paul; Ertz, Damien (2020). "First checklist of lichens and lichenicolous fungi from Mauritius, with phylogenetic analyses and description of new taxa". Plant and Fungal Systematics. 65 (1): 13–75. doi: 10.35535/pfsyst-2020-0003 .
  3. Gueidan, Cécile; Aptroot, André; Cáceres, Marcela Eugenia da Silva; Binh, Nguyen Quoc (2016). "Molecular phylogeny of the tropical lichen family Pyrenulaceae: contribution from dried herbarium specimens and FTA card samples". Mycological Progress. 15 (1): 1–21. Bibcode:2016MycPr..15....7G. doi:10.1007/s11557-015-1154-8.