''Hypotrachyna brueggeri'' is a species of

foliose lichen A foliose lichen is a lichen with flat, leaf-like , which are generally not firmly bonded to the substrate on which it grows. It is one of the three most common growth forms of lichens. It typically has distinct upper and lower surfaces, each o ...

in the family

Parmeliaceae The Parmeliaceae is a large and diverse family of Lecanoromycetes. With over 2700 species in 71 genera, it is the largest family of lichen-forming fungi. The most speciose genera in the family are the well-known groups: '' Xanthoparmelia'' ( 82 ...

. Described as a new species in 2002, it is known only from the type locality in southeastern Brazil, where it was collected at elevations of . This lichen forms sprawling rosettes 10–15 cm across with broad, overlapping and is distinguished by distinctive branched that give its surface a rough texture. It grows on both tree bark and

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

rocks in the moist

montane Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...

forests of the Mantiqueira and

Serra do Mar The Serra do Mar (; ) is a system of mountain ranges and escarpments in Southeast Region, Brazil, Southeastern Brazil. Geography The Serra do Mar runs parallel to the Atlantic Ocean coast from the state of Espírito Santo to southern Santa Ca ...

mountain systems, where persistent fog provides the humid conditions it requires.

Taxonomy

''Hypotrachyna brueggeri'' was introduced to science in 2002 by C.H. Ribeiro and M.P. Marcelli during their systematic survey of parmelioid lichens in south-eastern Brazil. The

type specimen In biology, a type is a particular wikt:en:specimen, specimen (or in some cases a group of specimens) of an organism to which the scientific name of that organism is formally associated. In other words, a type is an example that serves to ancho ...

was collected in montane Atlantic Forest at Parque Estadual do Ibitipoca (

Minas Gerais Minas Gerais () is one of the 27 federative units of Brazil, being the fourth largest state by area and the second largest in number of inhabitants with a population of 20,539,989 according to the 2022 Brazilian census, 2022 census. Located in ...

) from the trunk of a

candeia Antônio Candeia Filho better known as Candeia (August 17, 1935 – November 16, 1978) was a Brazilian samba singer, songwriter, and musician. Early life Born in Rio de Janeiro to Antonio Candeio and Dona Maria, Antonio was a renowned flautist ...

(''Eremanthus erythropappus'') in a well-lit patch of forest on 19 March 1994. The authors placed the species in the large

foliose A foliose lichen is a lichen with flat, leaf-like , which are generally not firmly bonded to the substrate on which it grows. It is one of the three most common lichen growth forms, growth forms of lichens. It typically has distinct upper and lo ...

genus ''

Hypotrachyna ''Hypotrachyna'' is a genus of lichenized fungi within the family Parmeliaceae. According to the ''Dictionary of the Fungi'' (10th edition, 2008), the widespread genus contains about 198 species. ''Hypotrachyna'' was circumscribed by American lic ...

'' (family Parmeliaceae), which is typified by a black-rimmed lower surface and a suite of

secondary metabolite Secondary metabolites, also called ''specialised metabolites'', ''secondary products'', or ''natural products'', are organic compounds produced by any lifeform, e.g. bacteria, archaea, fungi, animals, or plants, which are not directly involved ...

s. The

species epithet Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In Taxonomy (biology), taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany) ...

commemorates the Brazilian botanist Márcio Caetano Brüegger, whose work helped protect and document the flora of Ibitipoca. Chemically, ''H. brueggeri'' is defined by a layer rich in atranorin and a medulla that contains protocetraric acid alongside several unidentified compounds. Spot tests produce a K+ (yellow) reaction in the , while the medulla is P+ (yellow) but otherwise unresponsive; neither cortex nor medulla

fluoresce Fluorescence is one of two kinds of photoluminescence, the emission of light by a substance that has absorbed light or other electromagnetic radiation. When exposed to ultraviolet radiation, many substances will glow (fluoresce) with color ...

under

ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...

light. This chemical fingerprint, together with the presence of distinctive pustules (see below), separates the

taxon In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...

from superficially similar species such as '' H. dactylifera'' and '' H. consimilis''.

Description

The

thallus Thallus (: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. A thallus usually names the entir ...

forms lax, rather sprawling rosettes 10–15 cm across. Its surface is dull white, ageing to pale grey, and is divided into broad, flattened lobes () 2–4 mm wide. Lobes overlap like roof tiles and may arch slightly upwards; their tips are square-cut and edged by a fine black line, a common trait in ''Hypotrachyna''. Unlike many in the genus, the thallus lacks (pale blotches),

soredia Soredia are common reproduction, reproductive structures of lichens. Lichens asexual reproduction, reproduce asexually by employing simple fragmentation and production of soredia and isidia. Soredia are powdery propagules composed of fungus, fung ...

(powdery

propagule In biology, a propagule is any material that functions in propagating an organism to the next stage in its life cycle, such as by dispersal. The propagule is usually distinct in form from the parent organism. Propagules are produced by organisms ...

s) and true

isidia An isidium (plural: isidia) is a tiny, wart- or finger-like outgrowth on the thallus surface of certain lichen species. It is one of two principal types of vegetative reproduction, vegetative reproductive structures in lichens, the other being ...

(finger-like outgrowths). Instead, it carries crowded, branched —small blister-like swellings that originate from inflated isidia but do not break open to release powder. These "isidioid pustules" reach 0.5–1.5 mm in height and give the surface a distinctly rough texture. Internally, the medulla is snow-white. The lower surface is black, wrinkled and traversed by low veins; around the margin it bears plentiful

rhizine In lichens, rhizines are multicellular root-like structures arising mainly from the lower surface. A lichen with rhizines is termed rhizinate, while a lichen lacking rhizines is termed erhizinate. Rhizines serve only to anchor the lichen to their s ...

s—forked, root-like fibres 0.5–1 mm long that anchor the lichen to its

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

. No sexual fruit-bodies (

apothecia An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. As ...

) or flask-shaped

asexual Asexual or Asexuals may refer to: *Asexual reproduction **Asexual reproduction in starfish *Asexuality, the lack of sexual attraction to anyone or lack of interest in or desire for sexual activity. **Gray asexuality, the spectrum between asexualit ...

structures (

pycnidia A pycnidium (plural pycnidia) is an asexual fruiting body produced by mitosporic fungi, for instance in the order Sphaeropsidales ( Deuteromycota, Coelomycetes) or order Pleosporales (Ascomycota, Dothideomycetes). It is often spherical or inve ...

) have yet been observed, suggesting that the species relies mainly on vegetative dispersal via fragments or the persistent pustules.

Habitat and distribution

''Hypotrachyna brueggeri'' is confirmed from two moist

localities in south-eastern Brazil. The holotype was found at roughly 1,100–1,200 m in the Serra do Ibitipoca (Minas Gerais), where mist-laden Atlantic Forest intergrades with open candeia woodland. Here the lichen colonises the bark of living candeia trees in well-illuminated but humid forest edges. A second gathering comes from Campos do Jordão State Park in neighbouring

São Paulo São Paulo (; ; Portuguese for 'Paul the Apostle, Saint Paul') is the capital of the São Paulo (state), state of São Paulo, as well as the List of cities in Brazil by population, most populous city in Brazil, the List of largest cities in the ...

state (about 1,400 m elevation), where it was found on

boulders beside the Sapucaí-Guaçu River, indicating that the species can occupy both lignicolous (wood-dwelling) and

saxicolous This glossary of mycology is a list of definitions of terms and concepts relevant to mycology, the study of fungi. Terms in common with other fields, if repeated here, generally focus on their mycology-specific meaning. Related terms can be found ...

(rock-dwelling) niches provided the

microclimate A microclimate (or micro-climate) is a local set of atmosphere of Earth, atmospheric conditions that differ from those in the surrounding areas, often slightly but sometimes substantially. The term may refer to areas as small as a few square m ...

remains cool and persistently moist. Because collections are few despite intensive surveys in surrounding ranges, ''H. brueggeri'' may be genuinely localised to the fog-prone highlands of the Mantiqueira and Serra do Mar systems. Equally, its whitish thallus and lack of conspicuous reproductive structures mean it could be overlooked among larger foliose species.

References

{{Taxonbar, from=Q10530463 brueggeri Lichen species Lichens described in 2002 Lichens of Southeast Brazil