''Rusavskia'' is a

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 ...

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 ...

-forming

fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...

in the family Teloschistaceae. It has 12 species. It is a member of the subfamily Xanthorioideae. 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 ...

of ''Rusavskia'' is characterised by its

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 ...

(leaf-like) structure with distinct and typically narrow that curve outwards.

Taxonomy

The genus ''Rusavskia'' was proposed by lichenologists

Sergey Kondratyuk Sergey Yakovlevich Kondratyuk () (born 17 May 1959) is a Ukrainian botanist specialising in lichenology. His research deals with the taxonomy, floristics, ecology and geography of lichens and lichenicolous fungi. He has worked at the for mo ...

and

Ingvar Kärnefelt Jan Eric Ingvar Kärnefelt (born 1944) is a Swedish lichenologist. Early life and education Kärnefelt was born in Gothenburg, Sweden in 1944. His initial goal in his higher-level studies at University of Cologne in 1966–1967 was to become a ...

in 2003, with '' Rusavskia elegans'' assigned as the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

. The initial

circumscription Circumscription may refer to: * Circumscribed circle * Circumscription (logic) *Circumscription (taxonomy) * Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthr ...

of the genus relied predominantly on an evaluation of morphological, anatomical and chemical characteristics, with a notable absence of

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 ...

analysis. For this reason, the reception of the ''Rusavskia'' by lichenologists was initially met with cautious appraisal. As several molecular studies in the subsequent years showed, the ''Rusavskia elegans''-group occupies a separate

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 ...

branch in the Teloschistaceae; the growing body of molecular evidence led to the acceptance of the genus ''Rusavskia''.

Description

''Rusavskia'' is characterised by its

(leaf-like) structure with distinct and typically narrow that curve outwards. These lobes often feature

pseudocyphella Pseudocyphellae (singular ''pseudocyphella'') are structures in lichens that appear as tiny pores on the outer surface (the cortex) of the lichen. They are caused when there is a break in the cortex of the lichen, and the medullary hyphae extend ...

e – tiny, white porous areas on the lichen's surface. The lichen adheres to surfaces using short, root-like structures called . Its reproductive structures, known as

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 in form and display a noticeable orange hue. The produced are

ellipsoid An ellipsoid is a surface that can be obtained from a sphere by deforming it by means of directional Scaling (geometry), scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a Surface (mathemat ...

in shape, and , with a moderately divided central region (

septa SEPTA, the Southeastern Pennsylvania Transportation Authority, is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly four million people througho ...

). Additionally, ''Rusavskia'' may possess , which are embedded reproductive structures, and produce ellipsoid-shaped (asexual spores). ''Rusavskia'' was distinguished from ''Xanthoria'' due to several unique characteristics. Unlike ''Xanthoria'', ''Rusavskia'' has a mesodermate cortex, which contrasts the earlier belief of it being . While it was believed to lack attachment organs, it was later found that species like ''R. elegans'' and ''R. sorediata'' have hapters, albeit short ones. The (asexual spores) of ''Rusavskia'' are primarily ellipsoid, with only a minority being , contrary to earlier descriptions. In terms of morphology, ''Rusavskia'' predominantly differs from ''Xanthoria'' by its narrower lobes. When compared to '' Dufourea'', ''Rusavskia'' stands out due to its narrow lobes that adhere more closely to surfaces. Although some experts hesitated to accept the distinct classification of ''Rusavskia'', genetic evidence firmly sets it apart from ''Xanthoria'' and other related groups.

Species

Species Fungorum ''Index Fungorum'' is an international project to index all formal names (Binomial nomenclature, scientific names) in the fungus Kingdom (biology), kingdom. As of 2015, the project is based at the Royal Botanic Gardens, Kew, one of three partn ...

(in the

Catalogue of Life The Catalogue of Life (CoL) is an online database that provides an index of known species of animals, plants, fungi, and microorganisms. It was created in 2001 as a partnership between the global Species 2000 and the American Integrated Taxono ...

) accepts 12 species of ''Rusavskia''.

* '' Rusavskia aspera'' * '' Rusavskia crassa'' * '' Rusavskia dasanensis'' * '' Rusavskia drevlyanica'' * '' Rusavskia ectaniza'' * '' Rusavskia elegans'' * '' Rusavskia granulifera'' * '' Rusavskia hafellneri'' * '' Rusavskia indica'' * '' Rusavskia indochinensis'' * '' Rusavskia sorediata'' * '' Rusavskia subfruticulosa'' * '' Rusavskia upretii''

References

{{Taxonbar, from=Q21215467 Teloschistales Teloschistales genera Lichen genera Taxa described in 2003 Taxa named by Ingvar Kärnefelt Taxa named by Sergey Kondratyuk