''Sagenidiopsis'' 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

Arthoniaceae The Arthoniaceae are a family (biology), family of lichenized, Lichenicolous fungus, lichenicolous and saprobic fungi in the order Arthoniales. The Arthoniaceae is the largest family of Arthoniales, with around 800 species. Most species in Arthon ...

. It was

circumscribed In geometry, a circumscribed circle for a set of points is a circle passing through each of them. Such a circle is said to ''circumscribe'' the points or a polygon formed from them; such a polygon is said to be ''inscribed'' in the circle. * Circum ...

in 1987 by lichenologists Roderick Rogers and

Josef Hafellner Josef Hafellner (1951– ) is an Austrian mycologist and lichenologist. He was awarded the Acharius Medal in 2016 for his lifetime contributions to lichenology. Before his retirement, he was a professor at the Karl-Franzens-Universität in Graz ...

to contain 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 ...

'' S. merrotsii'', found in Australia. The characteristic features of the genus include the byssoid (cottony)

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 bitunicate asci (enclosed in a double wall) that lack

amyloid Amyloids are aggregates of proteins characterised by a fibrillar morphology of typically 7–13 nm in diameter, a β-sheet secondary structure (known as cross-β) and ability to be stained by particular dyes, such as Congo red. In the human ...

structures that are apparent in the thallus.

Description

''Sagenidiopsis'' is characterized by its distinctive (cotton-like)

, which forms extensive, thick, and spongy crusts without a protective outer layer. The thallus structure is differentiated into two parts: an upper layer containing loosely woven fungal

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 o ...

e that incorporate filaments of the algal partner '' Trentepohlia'', and a lower layer consisting purely of fungal tissue without algae. The fungal component penetrates the algal cells with specialized structures called

haustoria In botany and mycology, a haustorium (plural haustoria) is a rootlike structure that grows into or around another structure to absorb water or nutrients. For example, in mistletoe or members of the broomrape family, the structure penetrates th ...

to extract nutrients. Reproductive structures (

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

) of ''Sagenidiopsis'' begin as closed, globular bodies that later open to develop a circular . These structures have a distinctive margin covered in free hyphae similar to those of the thallus, which conceals the (the true rim of the fruiting body). Inside, the asci (spore-producing cells) are (having a double wall that splits during spore release) with a long stalk. Unlike related genera, the asci lack any

structures (parts that

stain A stain is a discoloration that can be clearly distinguished from the surface, material, or medium it is found upon. They are caused by the chemical or physical interaction of two dissimilar materials. Accidental staining may make materials app ...

blue with

iodine Iodine is a chemical element; it has symbol I and atomic number 53. The heaviest of the stable halogens, it exists at standard conditions as a semi-lustrous, non-metallic solid that melts to form a deep violet liquid at , and boils to a vi ...

) in the (tip region). The spores are

hyaline A hyaline substance is one with a glassy appearance. The word is derived from , and . Histopathology Hyaline cartilage is named after its glassy appearance on fresh gross pathology. On light microscopy of H&E stained slides, the extracellula ...

(colourless), thin-walled, and divided by transverse

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 ...

. When first described, the genus contained only a single species, ''Sagenidiopsis merrotsii'', which was found in cool temperate rainforests of the

Mcpherson Range The McPherson Range is an extensive mountain range, a spur of the Great Dividing Range, heading in an easterly direction from near Wallangarra, Queensland, Wallangarra to the Pacific Ocean coastline. It forms part of the Scenic Rim on the border ...

in eastern Australia. This species grows on tree trunks and overhanging rock faces in misty, humid environments, particularly near ''

Nothofagus moorei ''Nothofagus moorei'', commonly known as Antarctic beech, is a species of flowering plant in the family Nothofagaceae that is endemic to high altitude areas of eastern Australia. It is a tree, with simple leathery, glossy, egg-shaped to lance-sh ...

'' (Antarctic beech) forests. The thallus appears orange when fresh but fades to greyish-green or greyish-yellow when dry. The byssoid thallus form is not unique to ''Sagenidiopsis'' but represents an ecological adaptation that has evolved independently in several unrelated lichen families. This growth form, with its high surface area-to-weight ratio, appears to be specialized for efficient absorption of water vapour from humid air in environments where surfaces rarely receive direct rainfall or water flow.

Species

* '' Sagenidiopsis atroalba'' * '' Sagenidiopsis isidiata'' * '' Sagenidiopsis merrotsyi'' * '' Sagenidiopsis subconfluentica'' – Australia * '' Sagenidiopsis undulata''

References

{{Taxonbar, from=Q7399189 Roccellaceae Arthoniomycetes genera Lichen genera Taxa described in 1987 Taxa named by Josef Hafellner