''Ainoa'' 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 ...

s in the family

Baeomycetaceae The Baeomycetales are an order (biology), order of mostly lichen-forming fungi in the subclass Ostropomycetidae, in the class Lecanoromycetes. It contains 8 family (biology), families, 33 genus, genera and about 170 species. As a result of molecu ...

. It was named in honour of the German lichenologist

Aino Henssen Aino Marjatta Henssen (12 April 1925, Elberfeld – 29 August 2011, Marburg), was a German lichenologist and systematist. Her father, Gottfried Henssen, was a folklorist and her mother was Finnish. Education and career Henssen began her studies ...

. These rock-dwelling lichens form thin crusts that break into small flakes and are distinguished by their abundant dark brown to black button-like fruiting bodies that sit on short stalks. The genus includes three species found in cool

mountainous A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher t ...

regions, where they grow on hard

siliceous rock Siliceous rocks are sedimentary rocks that have silica (SiO2) as the principal constituent. The most common siliceous rock is chert; other types include diatomite. They commonly form from silica-secreting organisms such as radiolarians, diatoms, o ...

s and can withstand repeated cycles of wetting and drying.

Taxonomy

The genus 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 2001 by H. Thorsten Lumbsch and Imke Schmitt to contain two species that were formerly placed in genus '' Trapelia''. A third species, '' Ainoa bella'' from eastern North America, was added to the genus in 2015.

Description

''Ainoa'' forms a thin, crust-like lichen body (

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 ...

) that adheres tightly to bare rock. In some specimens the surface breaks along stress lines (), producing minute flakes that can act as vegetative

propagule In biology, a propagule is any material that functions in propagating an organism to the next stage in its life cycle, such as by dispersal. The propagule is usually distinct in form from the parent organism. Propagules are produced by organisms ...

s. A translucent of dead fungal cells coats the crust and gives it a slightly frost-like appearance, while any outer is absent. The internal

photosynthetic Photosynthesis ( ) is a Biological system, system of biological processes by which Photoautotrophism, photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical ener ...

partner is a simple, spherical

green alga The green algae (: green alga) are a group of chlorophyll-containing autotrophic eukaryotes consisting of the phylum Prasinodermophyta and its unnamed sister group that contains the Chlorophyta and Charophyta/ Streptophyta. The land plants ( ...

(a photobiont) that sits just beneath the surface; this arrangement means the lichen shows no orange tint when scratched, unlike species that harbour '' Trentepohlia''. Fertile structures are abundant and conspicuous. Each

apothecium 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. Ascoc ...

(fruiting body) is a small, round that sits directly on the thallus but narrows to a stalk-like base, giving it a button-on-a-pin profile. The disc itself is dark brown to almost black, flat to slightly cupped, and surrounded by a raised margin that persists for the life of the fruit body. Supporting this margin is a cup-shaped layer (the ) composed of long, thick-walled

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 darken with age. Above the exciple lies a clear spore-bearing layer (

hymenium The hymenium is the tissue layer on the hymenophore of a fungal fruiting body where the cells develop into basidia or asci, which produce spores. In some species all of the cells of the hymenium develop into basidia or asci, while in oth ...

) 90–150 μm tall; it is threaded by slender,

septate In biology, a septum (Latin for ''something that encloses''; septa) is a wall, dividing a cavity or structure into smaller ones. A cavity or structure divided in this way may be referred to as septate. Examples Human anatomy * Interatrial se ...

filaments (

paraphyses Paraphyses are erect sterile filament-like support structures occurring among the reproductive apparatuses of fungi, ferns, bryophytes and some thallophytes. The singular form of the word is paraphysis. In certain fungi, they are part of the f ...

) that branch sparingly and separate readily when mounted in water, a trait that helps distinguish the genus. The asci are cylindrical, hold eight

ascospore In fungi, an ascospore is the sexual spore formed inside an ascus—the sac-like cell that defines the division Ascomycota, the largest and most diverse Division (botany), division of fungi. After two parental cell nucleus, nuclei fuse, the ascu ...

s, and have a faintly blue-

staining Staining is a technique used to enhance contrast in samples, generally at the Microscope, microscopic level. Stains and dyes are frequently used in histology (microscopic study of biological tissue (biology), tissues), in cytology (microscopic ...

apical dome typical of the '' Trapelia'' type. Spores are narrowly

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 ...

al, colourless, and lack both internal septa and the gelatinous sheath seen in many other

crustose lichen Crustose lichens are lichens that form a crust which strongly adheres to the Substrate (biology), substrate (soil, rock, tree bark, etc.), making separation from the substrate impossible without destruction. The basic structure of crustose lichen ...

s. ''Ainoa'' also produces

asexual Asexual or Asexuals may refer to: *Asexual reproduction **Asexual reproduction in starfish *Asexuality, the lack of sexual attraction to anyone or lack of interest in or desire for sexual activity. **Gray asexuality, the spectrum between asexualit ...

spores in tiny flask-shaped

pycnidia A pycnidium (plural pycnidia) is an asexual fruiting body produced by mitosporic fungi, for instance in the order Sphaeropsidales ( Deuteromycota, Coelomycetes) or order Pleosporales (Ascomycota, Dothideomycetes). It is often spherical or inve ...

embedded within wart-like swellings of the thallus. These pycnidia release very small, rod-shaped

conidia A conidium ( ; : conidia), sometimes termed an asexual chlamydospore or chlamydoconidium (: chlamydoconidia), is an asexual, non- motile spore of a fungus. The word ''conidium'' comes from the Ancient Greek word for dust, ('). They are also ...

. Chemically the genus is simple: the only consistently detected compound is

gyrophoric acid Gyrophoric acid is a tridepside. It is a double ester of the orsellinic acid. It can also be found in most of the species of the lichen genera '' Actinogyra'', '' Lasallia'', and '' Umbilicaria'' . Natural occurrence and biosynthesis Gyropho ...

, and even that is confined to the fruit bodies and pycnidia rather than permeating the entire crust.

Ecology

All known species are

saxicolous This glossary of mycology is a list of definitions of terms and concepts relevant to mycology, the study of fungi. Terms in common with other fields, if repeated here, generally focus on their mycology-specific meaning. Related terms can be found ...

, preferring hard,

in cool, often

alpine Alpine may refer to any mountainous region. It may also refer to: Places Europe * Alps, a European mountain range ** Alpine states, which overlap with the European range Australia * Alpine, New South Wales, a Northern Village * Alpine National P ...

environments where periodic wetting and drying favour lichens that can cling closely to their

substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached ** Substrate (aquatic environment), the earthy material that exi ...

References

{{Taxonbar, from=Q4697464 Baeomycetales Baeomycetales genera Lichen genera Taxa described in 2001 Taxa named by Helge Thorsten Lumbsch