lichen
A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.fungi in the family Teloschistaceae. It has four species of saxicolous (rock-dwelling), crustose lichens that occur in Australasia.
Taxonomy
''Elixjohnia'' was
circumscribed
In geometry, the circumscribed circle or circumcircle of a polygon is a circle that passes through all the vertices of the polygon. The center of this circle is called the circumcenter and its radius is called the circumradius.
Not every po ...
in 2017 by
Sergey Kondratyuk
Sergey Yakovlevich Kondratyuk ( uk, Сергій Якович Кондратюк) (born 17 May 1959) is a Ukrainian botanist specialising in lichenology. His research deals with the taxonomy, floristics, ecology and geography of lichens and lic ...
and Jae-Seoun Jur in 2017, with '' Elixjohnia jackelixii'' assigned as the type species. Phylogenetic analysis shows that the genus is in the large ''
Sirenophila
''Sirenophila'' is a genus of crustose lichens in the subfamily Teloschistoideae of the family Teloschistaceae. It has four species with an Australasian distribution.
Taxonomy
The genus was circumscribed in 2013 by Ulrik Søchting, Ulf Arup, and ...
''-''
Teloschistopsis
''Teloschistopsis'' is a genus of lichen-forming fungi in the family Teloschistaceae. It has three species.
Taxonomy
The genus was circumscribed by Patrik Frödén, Ulrik Søchting, and Ulf Arup in 2013, as part of a molecular phylogenetics-led ...
''-''Halophila'' sub
clade
A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – on a phylogenetic tree. Rather than the English term, ...
of the subfamily Teloschistoideae (family Teloschistaceae). The genus name honours Australian chemist and lichenologist John A. ("Jack") Elix.
The existence and phylogenetic structure of the genus was corroborated by
molecular
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...
work published by Wilk and colleagues in 2021.
Description
''Elixjohnia'' is characterised by a thallus that is typically , presenting initial appearances of brownish or a dirty greenish yellow in sterile circles. These circles can be dull, smooth, and continuous in their peripheral zones, or may lack any zonation. The thallus is often notably thick, especially at its centre, but may also be evenly continuous. The texture varies, with some specimens being smooth and entire, while others are distinctly . Colours can range from whitish, yellowish, or greyish shades to brighter hues of red or reddish-orange. Over time, the upper surface can become cracked and eroded, occasionally revealing isidia-like formations. In many cases, the medulla, or inner tissue, is exposed through these cracks.
Adjacent to the thallus is the , which can either be well-developed or completely absent. The , or spore-producing structures, are frequently observed and tend to be small in size. In some species, these apothecia are , at least initially, but can also be or in form. Their is often a brownish-orange or yellowish-brown shade, sometimes with hints of red or even transitioning to a dull orange or a bright scarlet. Microscopically, the (outer rim of the apothecium) is made of tissue. The , or sterile fungal filaments, contain oil cells of the bermaguiana-type. Typically, there are eight spores in each
ascus
An ascus (; ) is the sexual spore-bearing cell produced in ascomycete fungi. Each ascus usually contains eight ascospores (or octad), produced by meiosis followed, in most species, by a mitotic cell division. However, asci in some genera or s ...
, but it is not uncommon to find 2, 4, or 6 mature bipolar ascospores accompanied by aborted ones. These ascospores can range from narrowly to broadly
ellipsoid
An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation.
An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...
in shape. Finally, the , or asexual spores, are broad and either ellipsoid or , with measurements typically falling between 2–3 by 1.2–1.7
μm
The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...
lichen substance
Lichen products, also known as lichen substances, are organic compounds produced by a lichen. Specifically, they are secondary metabolites. Lichen products are represented in several different chemical classes, including terpenoids, orcinol de ...
associated with this genus.
Habitat and distribution
''Elixjohnia'' species predominantly colonise exposed coastal rocks, including quartzite, granite, basalt, and dolerite. These lichens are typically found at or above the high tide level. It is not uncommon to find species such as ''E. jackelixii'' and ''E. gallowayi'' growing alongside each other. Additionally, they often share their habitat with species from various genera, including '' Tarasginia whinrayi'', '' T. tomareana'', ''
Sirenophila eos
''Sirenophila eos'' is a species of saxicolous (rock-dwelling), crustose lichen in the family Teloschistaceae. It was first formally described as a new species in 2007 by Sergey Kondratyuk and Ingvar Kärnefelt, as ''Caloplaca eos''. The type ...
Elixjohnia ovis-atra
''Elixjohnia'' is a genus of lichen-forming fungi in the family Teloschistaceae. It has four species of saxicolous lichen, saxicolous (rock-dwelling), crustose lichens that occur in Australasia.
Taxonomy
''Elixjohnia'' was circumscription (taxo ...