Calvitimela Perlata
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''Calvitimela'' is a fungal
genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
in the family
Tephromelataceae The Tephromelataceae are a family of lichenized fungi in the order Lecanorales. The family was circumscribed by Austrian lichenologist Josef Hafellner in 1984. Tephromelataceae comprises the genera '' Tephromela'', '' Calvitimela'', '' Mycoblast ...
, comprising 11 species of
lichen A lichen ( , ) is a hybrid colony (biology), colony of algae or cyanobacteria living symbiotically among hypha, filaments of multiple fungus species, along with yeasts and bacteria embedded in the cortex or "skin", in a mutualism (biology), m ...
. These lichens grow tightly attached to rocks, appearing as thin, crust-like layers on their surface. They are primarily found in alpine and arctic regions around the world. ''Calvitimela'' species are characterised by their (segmented)
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 ...
and black, shiny, convex
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 ...
(fruiting bodies). The genus currently includes eleven recognised species, though recent genetic studies have revealed unexpected diversity within this group. ''Calvitimela'' lichens are known for their varied
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, which can sometimes aid in species identification. However, the taxonomy of the genus remains complex and challenging, with ongoing research uncovering new information about their relationships, distribution, and evolution. These lichens play important ecological roles in their harsh mountain and polar habitats, where they are often among the few organisms able to thrive.


Taxonomy

The taxonomic history of ''Calvitimela'' is long and relatively complex. In the early days, the species now belonging to ''Calvitimela'' were placed in the classical genus ''
Lecidea ''Lecidea'' is a genus of crustose lichen, crustose lichens with a carbon-black ring or outer margin (exciple) around the fruiting body disc (apothecium), usually (or always) found growing on (Saxicolous lichen, saxicolous) or in (Endolithic lich ...
'' Ach., e.g. by Fries (1874; as ''Lecidea'' stirps ''L. armeniacae''). and Magnusson (1931; as "''Lecidea armeniaca''- und ''elata''-Gruppe") In the 1980s, several taxonomists revised large groups of lichens in ''
Lecanora ''Lecanora'' is a genus of lichen commonly called rim lichens.Field Guide to California Lichens, Stephen Sharnoff, Yale University Press, 2014, Lichens in the genus '' Squamarina'' are also called rim lichens. Members of the genus have roughly c ...
'' and ''
Lecidea ''Lecidea'' is a genus of crustose lichen, crustose lichens with a carbon-black ring or outer margin (exciple) around the fruiting body disc (apothecium), usually (or always) found growing on (Saxicolous lichen, saxicolous) or in (Endolithic lich ...
''. First, the
generic Generic or generics may refer to: In business * Generic term, a common name used for a range or class of similar things not protected by trademark * Generic brand, a brand for a product that does not have an associated brand or trademark, other ...
name '' Tephromela'' was resurrected, and the new
monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...
family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
Tephromelataceae The Tephromelataceae are a family of lichenized fungi in the order Lecanorales. The family was circumscribed by Austrian lichenologist Josef Hafellner in 1984. Tephromelataceae comprises the genera '' Tephromela'', '' Calvitimela'', '' Mycoblast ...
described. Then, a group from ''Lecidea'' was moved into the genus ''Tephromela'' M. Choisy. This led to species with both lecanorine and lecideine
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 ...
being present in the same genus. Finally, the genus ''Calvitimela'' was erected for species with lecideine apothecia previously placed in ''Tephromela''. Recent molecular phylogenetic studies have revealed that the taxonomy of ''Calvitimela'' is more complex than previously thought. The genus is now understood to be paraphyletic, with its subgenera and the genus ''Violella'' forming deeply divergent lineages that originated about 35 million years ago. The family
Tephromelataceae The Tephromelataceae are a family of lichenized fungi in the order Lecanorales. The family was circumscribed by Austrian lichenologist Josef Hafellner in 1984. Tephromelataceae comprises the genera '' Tephromela'', '' Calvitimela'', '' Mycoblast ...
consists of the genera '' Tephromela'', ''Calvitimela'', '' Mycoblastus'' and '' Violella'', which together constitute a well-supported monophyletic group. However, resolving the deep phylogenetic relationships within Tephromelataceae has proven challenging, possibly due to incomplete lineage sorting or substitutional saturation. Within ''Calvitimela'', molecular studies have identified four distinct lineages in the subgenus Calvitimela, corresponding to ''C. armeniaca'', ''C. melaleuca'' I, ''C. melaleuca'' II, and the newly recognized ''C. melaleuca'' III. This renders ''C. melaleuca'', as traditionally circumscribed, paraphyletic. Additionally, a new clade sister to ''C. aglaea'' has been discovered within the subgenus Severidea. The current taxonomic placement of ''Calvitimela'' presents challenges for classification. Options include accepting a paraphyletic ''Calvitimela'', lumping all species in ''Calvitimela'', ''Tephromela'', and ''Violella'' into a broad ''Tephromela'', or raising the current subgenera to generic rank. Each option has its drawbacks, and further research is needed to resolve these taxonomic issues.


Description

The species of ''Calvitimela'' are
crustose lichens Crustose lichens are lichens that form a crust which strongly adheres to the substrate (soil, rock, tree bark, etc.), making separation from the substrate impossible without destruction. The basic structure of crustose lichens consists of a corte ...
. Their
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 ...
are areolate and their
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 ...
lecideine. The apothecia are convex, black and shiny.
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 ...
are rare or entirely absent in some sorediate species e.g. ''C. cuprea'', ''C. livida'' and ''C. talayana''. Asci are generally of the ''Lecanora''-type, but ''Bacidia''-type asci are also observed in ''C. aglaea'' and ''C. perlata''. The spores are usually simple and ellipsoid. Recent studies have revealed that thallus colour can be a diagnostic character for fresh specimens of ''C. melaleuca'' lineages. ''C. melaleuca'' I exhibits white to light brown thallus colour, ''C. melaleuca'' II shows yellow to brownish-yellow thallus colour, and ''C. melaleuca'' III has a beige coloured thallus. Spore size has been found to be an important morphological character. ''C. perlata'' has significantly larger spores compared to other taxa in ''Calvitimela''. The sister taxa ''C. melaleuca'' II and ''C. armeniaca'' have been observed to have narrower spores compared to other species in the genus. An esorediate and fertile morphotype of ''C. cuprea'' has been discovered, extending the morphological range of this species. This finding implies that different reproductive strategies can occur within the same species of ''Calvitimela''. There is much chemical variation of
secondary metabolites 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 ...
in the species of ''Calvitimela''. Most prominently observed in the ''C. melaleuca'' – complex, with , norstictic, roccellic and psoromic acids occurring in different combinations in the species´ several chemotypes. Recent studies have shown that the chemical profiles within subgenus Calvitimela are complex and overlapping, making it challenging to use chemistry as a diagnostic tool at the species level. In the subgenus Severidea, ''C. aglaea'' is distinguishable from other species by containing bourgeanic acid and usnic acid. Other species in this subgenus share atranorin and stictic acid as major compounds. The overall chemosyndrome in each subgenus of ''Calvitimela'' is distinct, making it informative at higher taxonomic levels. However, within subgenera, especially in subgenus Calvitimela, chemical characters are often homoplastic at the species level.


Ecology and distribution

All species of ''Calvitimela'' grow on rocks. The species in ''Calvitimela'' reside either on
boulders In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In c ...
of varying size or directly on mountainous walls and are occasionally found on pebbles. A peculiar ecological preference is observed in ''C. cuprea''. This species is more or less morphologically identical to ''C. livida'', but seem to only grow on
copper Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...
rich rocks, and is associated with old copper mine localities. Species in ''Calvitimela'' are predominantly distributed in alpine to arctic regions, and they seem to have a
circumpolar distribution A circumpolar distribution is any range (biology), range of a taxon that occurs over a wide range of longitudes but only at high latitudes; such a range therefore extends all the way around either the North Pole or the South Pole. Taxa that are al ...
. On the other hand, due to lack of sampling in certain regions of the world (e.g. Africa, Asia and South America), the true distribution of ''Calvitimela'' is only partly known. ''C. austrochilensis'' is described from Chile and ''C. uniseptata'' from Antarctica, respectively. These species have not yet been included in any
molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
studies. Therefore, whether they belong in ''Calvitimela'' or not, is yet to be confirmed by molecular data. Recent studies have provided more detailed insights into the ecology and distribution of ''Calvitimela'' species: The different lineages of ''C. melaleuca'' (I, II, and III) show potential altitudinal preferences. ''C. melaleuca'' II and a subclade of ''C. melaleuca'' I appear to be connected to higher elevations, while ''C. melaleuca'' I seems to be more widely distributed at lower altitudes in Norway. ''C. cuprea'' has been confirmed to have a strong association with heavy metal-rich substrates, particularly copper. However, it has been noted that some individuals have been collected outside of mining habitats, suggesting a wider ecological tolerance than previously thought. The ecological distinction between ''C. cuprea'' and ''C. livida'' has been further clarified. While ''C. cuprea'' is primarily associated with heavy metal rocks, ''C. livida'' has a wider habitat range. The newly discovered clade sister to ''C. aglaea'' (referred to as ''C.'' sp.) was found to be morphologically similar to ''C. perlata'', highlighting the importance of molecular data in understanding species distributions and ecology. The circumpolar distribution of ''Calvitimela'' has been further supported by recent sampling efforts. However, it has been emphasized that more extensive sampling, particularly in understudied regions such as Africa, Asia, and South America, is needed to fully understand the global distribution patterns of these lichens. The discovery of cryptic diversity within ''Calvitimela'', particularly in Norway, suggests that there may be significant undiscovered diversity at a global level. This underscores the need for more comprehensive sampling and molecular studies to fully elucidate the ecological niches and distribution patterns of ''Calvitimela'' species worldwide.


Phylogeny

Molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
has revolutionised the
taxonomy image:Hierarchical clustering diagram.png, 280px, Generalized scheme of taxonomy Taxonomy is a practice and science concerned with classification or categorization. Typically, there are two parts to it: the development of an underlying scheme o ...
of
crustose lichens Crustose lichens are lichens that form a crust which strongly adheres to the substrate (soil, rock, tree bark, etc.), making separation from the substrate impossible without destruction. The basic structure of crustose lichens consists of a corte ...
and revealed an extensive amount of
cryptic species In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...
diversity Diversity, diversify, or diverse may refer to: Business *Diversity (business), the inclusion of people of different identities (ethnicity, gender, age) in the workforce *Diversity marketing, marketing communication targeting diverse customers * ...
. In ''Calvitimela'' there are some species that are morphologically identical, but are genetically distinct and have different chemotypes. In the ''C. melaleuca''–
complex Complex commonly refers to: * Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe ** Complex system, a system composed of many components which may interact with each ...
at least two distinct chemical lineages are observed with no currently known morphological correlation. Recent phylogenetic analyses have significantly expanded our understanding of ''Calvitimela''. The subgenus Calvitimela now comprises four supported clades: ''C. armeniaca'', ''C. melaleuca'' I, ''C. melaleuca'' II, and the newly recognised ''C. melaleuca'' III. This discovery renders ''C. melaleuca'', as traditionally circumscribed, paraphyletic with respect to ''C. armeniaca''. Within the subgenus Severidea, ''C. aglaea'' has been shown to be genetically heterogeneous, with three highly supported groupings and one moderately supported grouping. A new clade, sister to ''C. aglaea'', has also been discovered in this subgenus. There have been few studies investigating ''Calvitimela'' from a
molecular phylogenetics Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
perspective. Only one
phylogeny A phylogenetic tree or phylogeny is a graphical representation which shows the evolutionary history between a set of species or Taxon, taxa during a specific time.Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, M ...
focusing exclusively on ''Calvitimela'' has been published. They found ''Calvitimela'', '' Tephromela'' and '' Violella'' to constitute a well-supported
monophyletic In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent co ...
group. The relationship between the main clades remained partly unresolved, however. No study has yet included all species currently circumscribed to ''Calvitimela'', but the genus is so far indicated to be
paraphyletic Paraphyly is a taxonomic term describing a grouping that consists of the grouping's last common ancestor and some but not all of its descendant lineages. The grouping is said to be paraphyletic ''with respect to'' the excluded subgroups. In co ...
. Challenges in resolving deep phylogenetic relationships within Tephromelataceae persist, possibly due to incomplete lineage sorting or substitutional saturation. Molecular dating estimates suggest that the major lineages in ''Calvitimela'' and ''Violella'' diverged about 35 million years ago, indicating they represent relatively old evolutionary lineages. The phylogenetic placement of two Southern Hemisphere species, ''C. austrochilensis'' and ''C. uniseptata'', remains uncertain. Molecular evidence suggests that ''C. uniseptata'' may belong to the genus ''Lecania'' rather than ''Calvitimela''. Future phylogenetic studies may benefit from whole-genome sequencing approaches and broader taxon sampling to better resolve the evolutionary relationships within ''Calvitimela'' and the Tephromelataceae.


Species

''Calvitimela'' includes eleven species: * '' Calvitimela aglaea'' * '' Calvitimela armeniaca'' * '' Calvitimela austrochilensis'' * '' Calvitimela cuprea'' * '' Calvitimela livida'' * '' Calvitimela melaleuca'' * '' Calvitimela perlata'' * '' Calvitimela septentrionalis'' * '' Calvitimela talayana'' * '' Calvitimela testaceoatra'' * '' Calvitimela uniseptata''


References

{{Taxonbar, from=Q10440768 Lecanorales Lecanorales genera Lichen genera Taxa named by Josef Hafellner Taxa described in 2001