''Chrysothrix occidentalis'' is a species of saxicolous (rock-dwelling)

dust lichen Dust lichens are lichens in either the genus Chrysothrix or genus Lepraria ''Lepraria'' is a genus of leprose crustose lichens that grows on its substrate like patches of granular, caked up, mealy dust grains.A taxonomic revision of the Nort ...

in the family

Teloschistaceae The Teloschistaceae are a large family of mostly lichen-forming fungi belonging to the class Lecanoromycetes in the division Ascomycota. The family, estimated to contain over 1800 species, was extensively revised in 2013, including the creation o ...

. This yellow lichen occurs in

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

in open ''

Eucalyptus ''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including '' Corymbia'', they are commonly known as euca ...

'' forests.

Taxonomy

It was formally described as a new species in 2007 by Australian lichenologists John Alan Elix and

Gintaras Kantvilas Gintaras Kantvilas (born 1956) is an Australian lichenologist, who earned his Ph.D in 1985 from the University of Tasmania with a thesis entitled ''Studies on Tasmanian rainforest lichens''. He has authored over 432 species names, and 167 gener ...

. The

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

was collected from the Darling Plateau in the Brookton Highway Nature Reserve in

at an altitude of , where, in ''

'' woodland, it was found growing on a sheltered

laterite Laterite is both a soil and a rock type rich in iron and aluminium and is commonly considered to have formed in hot and wet tropical areas. Nearly all laterites are of rusty-red coloration, because of high iron oxide content. They develop by ...

ledge. The species name, ''occidentalis'', means "west", and refers to the lichen's distribution in Western Australia.

Description

''Chrysothrix occidentalis'' has a powdery, crust-like appearance that ranges in colour from bright yellow to yellow-green or yellow-orange. It does not have a protective outer layer ( cortex and its structure is simple, adhering directly to its . The lichen forms small, somewhat round colonies about 0.5–1 cm wide, which can merge over time to form larger irregular patches up to 10 cm wide. These colonies consist of tiny structures called soredia, which are fine and round in shape, measuring between 20–80

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 ...

in width. The

photosynthetic Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in c ...

partner in this lichen, or , is a type of

green alga The green algae (singular: green alga) are a group consisting of the Prasinodermophyta and its unnamed sister which contains the Chlorophyta and Charophyta/Streptophyta. The land plants (Embryophytes) have emerged deep in the Charophyte alga as ...

e, which is spherical and roughly 15–18 μm wide. The

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

e comprising the internal network of fungal threads are 1.6–3 μm thick. No supporting base layer, known as the , is visible, and reproductive structures like apothecia and pycnidia have not been observed. Chemically, when tested, the lichen turns orange upon exposure to a solution of

potassium hydroxide Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exp ...

(K+). Its primary lichen products include leprapinic acid, with smaller amounts of calycin,

vulpinic acid Vulpinic acid is a natural product first found in and important in the symbiosis underlying the biology of lichens. It is a simple methyl ester derivative of its parent compound, pulvinic acid, and a close relative of pulvinone, both of which de ...

, and pulvinic dilactone.

Habitat and distribution

''Chrysothrix occidentalis'' is found in various places in the southwestern region of Western Australia. It typically grows on protected

granite Granite () is a coarse-grained (phaneritic) 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 cools and solidifies undergro ...

or laterite ledges within open ''Eucalyptus'' forests, ranging in altitudes between . Some lichens species frequently found alongside ''Chrysothrix occidentalis'' include '' Buellia substellulans'', '' Lecanora farinacea'', ''

Ramboldia petraeoides ''Ramboldia'' is a genus of lichen-forming fungi in the family Ramboldiaceae. The genus was circumscribed in 1994 by Gintaras Kantvilas and John Alan Elix. It was emended in 2008 by the inclusion of ''Pyrrhospora'' species containing the anthr ...

'', '' Xanthoparmelia antleriformis'', and '' X. tasmanica''.

References

{{Taxonbar, from=Q10452308

occidentalis This list of Latin and Greek words commonly used in systematic names is intended to help those unfamiliar with classical languages to understand and remember the scientific names of organisms. The binomial nomenclature used for animals and plants i ...

Lichen species Lichens described in 2007 Lichens of Australia Taxa named by John Alan Elix Taxa named by Gintaras Kantvilas