''Crocodia'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

foliose lichen Foliose lichen is one of the morphological classes of lichens, which are complex organisms that arise from the symbiotic relationship between fungi and a photosynthetic partner, typically algae. This partnership allows lichen to live in diverse ...

s in the family

Peltigeraceae The Peltigeraceae are a family of lichens in the order Peltigerales. The Peltigeraceae, which contains 15 genera and about 600 species, has recently (2018) been emended to include the families Lobariaceae and Nephromataceae. Many Peltigeraceae sp ...

. It has eight species. The genus has a

cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in appropriate habitats. Such a taxon, usually a species, is said to exhibit cosmopolitanism or cosmopolitism. The ext ...

, although most species occur in

temperate In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

and

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

regions of the Southern Hemisphere. The main characteristics of the genus that separate it from its parent genus, ''

Pseudocyphellaria ''Pseudocyphellaria'' is a genus of large, leafy lichens that are sometimes referred to as "specklebelly" lichens.Brodo, I. M., S. D. Sharnoff, and S. Sharnoff. 2001. ''Lichens of North America''. Yale University Press: New Haven. The genus has ...

'', include a yellow

medulla Medulla or Medullary may refer to: Science * Medulla oblongata, a part of the brain stem * Renal medulla, a part of the kidney * Adrenal medulla, a part of the adrenal gland * Medulla of ovary, a stroma in the center of the ovary * Medulla of th ...

and yellow

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 t ...

e (tiny pores for gas exchange) on the lower

thallus Thallus (plural: 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. Many of these organisms wer ...

surface.

Taxonomy

''Crocodia'' was originally proposed by German naturalist

Johann Heinrich Friedrich Link Johann Heinrich Friedrich Link (2 February 1767 – 1 January 1851) was a German naturalist and botanist. Biography Link was born at Hildesheim as a son of the minister August Heinrich Link (1738–1783), who taught him love of nature throug ...

in 1833, with ''Crocodia aurata'' assigned as the

type species In 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 species that contains the biological type specimen ...

. A 2013

molecular phylogenetics 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 ...

-based analysis of the Lobariaceae showed that the large genus ''Pseudocyphellaria'' was

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...

. In 2011, Jørgensen and Galloway had proposed to split ''Pseudocyphellaria'' into two genera, with the large

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, ...

containing the type species '' P. crocata'' to retain the original genus name. The genus name ''Crocodia'' was reinstated by Moncada and colleagues for the smaller ''P. aurata''

(containing ''P. aurata'' and ''P. clathrata''). Additional species were transferred to the genus soon after.

Description

Characteristics of the genus include a foliose (leafy)

, yellow

, and yellow

e on the lower thallus surface. The form of the thallus ranges from neat rosettes to irregularly spreading. The

photobiont A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.green algae 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 ...

(possibly from the genus '' Dictyochloropsis''), while cyanobacteria occur in internal cephalodia. The

apothecia An ascocarp, or ascoma (), 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. Ascocarps are mo ...

are pedicellate and usually pubescent or verrucose. The sexual spores (

ascospore 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 ...

s) are fusiform (spindle-shaped) to

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 ...

, brown, and usually have three

septa The Southeastern Pennsylvania Transportation Authority (SEPTA) is a regional public transportation authority that operates bus, rapid transit, commuter rail, light rail, and electric trolleybus services for nearly 4 million people in five coun ...

; the asexual spores (

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

) are colourless with a bacilliform shape. Compounds called

triterpenoid Triterpenes are a class of chemical compounds composed of three terpene units with the molecular formula C30H48; they may also be thought of as consisting of six isoprene units. Animals, plants and fungi all produce triterpenes, including squale ...

s are the usual

lichen product 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 deriva ...

s found in the genus; they include

derivatives The derivative of a function is the rate of change of the function's output relative to its input value. Derivative may also refer to: In mathematics and economics * Brzozowski derivative in the theory of formal languages * Formal derivative, an ...

of fernene and lupane, which are examples of

hopane Hopane is a natural chemical compound classified as a triterpene. It forms the central core of a variety of other chemical compounds which are collectively known as hopanoids. The first compound of the hopane family to be isolated and characteri ...

triterpenoids.

Species interactions

'' Capronia harrisiana'' is a

lichenicolous fungus A lichenicolous fungus is a parasitic fungus that only lives on lichen as the host. A lichenicolous fungus is not the same as the fungus that is the component of the lichen, which is known as a lichenized fungus. They are most commonly specific to ...

that has been recorded growing on ''Crocodia aurata'' in southeastern North America. Other lichenicolous fungi growing on members of ''Crocodia'' include '' Homostegia pelvetii'', '' Abrothallus parmeliarum'', '' Arthonia epiphyscia'', '' A. fuscorubella'', '' A. pelveti'', '' A. stictaria'', '' Lichenoconium plectocarpoides'', '' Nectria heterospora'' and '' Scutula epiblastemica''.

Habiat and distribution

''Crocodia'' lichens are generally found in oceanic habitats that are humid and sheltered. Collectively, the genus has a

, with the greatest diversity in the Southern Hemisphere.

Species

* '' Crocodia arvidssonii'' – South America;

Canary Islands The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...

* '' Crocodia aurata'' – widespread * '' Crocodia asticta'' * '' Crocodia aurora'' * '' Crocodia fossulata'' * '' Crocodia guilleminii'' * '' Crocodia poculifera'' – palaeotropics * '' Crocodia punctulata''

References

{{Taxonbar, from=Q47519611 Peltigerales Lecanoromycetes genera Lichen genera Taxa described in 1833 Taxa named by Johann Heinrich Friedrich Link