Anaptychia ciliaris, commonly known as the great ciliated lichen or eagle's claws, is a species of fruticose lichen in the family Physciaceae. It is predominantly found in Northern Europe, with its range extending to European Russia, the Caucasus, Central and Southern Europe, the Canary Islands, and parts of Asia. First mentioned in botanical literature by the Italian botanist Fabio Colonna in 1606, the species was formally described by Carl Linnaeus in 1753, who highlighted its unique physical characteristics such as its grey colour, its unusual leafy form with linear fringe-like segments, and the presence of hair-like structures (). This lichen is adaptable in its choice of , mostly growing on tree barks and less commonly on rocks.
Throughout history, the lichen has been used in early scientific investigations about lichen structure and development. Early botanists like Joseph Pitton de Tournefort and Johann Hedwig made observations about the lichen's structure. More recent studies have investigated its potential biological activities, including antibacterial, insecticidal, and antioxidant properties. A. ciliaris has been used in research to monitor atmospheric pollution, including detecting air pollution following the Chernobyl disaster. Beyond its scientific importance, the lichen has had various practical applications. For example, in the 17th century, it was one of several lichen ingredients in "Cyprus Powder", used as a personal grooming and cosmetic product.
Anaptychia ciliaris is readily recognizable by its fruticose (bushy) thallus that varies in colour from greyish-white to brownish-grey, to greenish when wet, and its large and distinctive cilia. The lichen can form extensive colonies made of neighbouring lichens each attached to the at a single point, all with narrow , known as , growing outwards. These laciniae, which are covered in fine hairs, split repeatedly into equal branches. Circular reproductive structures () with brown occur on the thallus surface. The internal anatomy of A. ciliaris makes it sensitive to air pollutants, leading to observable changes in its form when exposed to these conditions. Two species of green algae in the genus Trebouxia have been shown to serve as the s (photosynthetic partners) of this lichen.
Taxonomy
According to Annie Lorrain Smith, Anaptypia ciliaris was first mentioned in the botanical literature in 1606 by the Italian botanist Fabio Colonna in his Ekphrasis, a work known for its detailed illustrations of plants using copperplate engravings. It was formally described as a new species in 1753 by Carl Linnaeus, as Lichen ciliaris. Linnaeus described it as a somewhat erect, leafy, grey lichen with linear, fringe-like segments that are ciliate (having hair-like structures, or ). He said it resembled a tree moss with hairy edges and small shield-like structures (apothecia). Linnaeus cited multiple references that described the lichen similarly, emphasizing its larger size, hairy characteristics, and shielded appearance. Linnaeus noted that this lichen is found on trees in Europe. Julius von Flotow is credited with the transfer of the taxon to the genus Anaptychia in 1850. A specimen illustrated by Johann Jacob Dillenius in 1742 was selected as the lectotype by Syo Kurokawa in his 1962 monograph on the genus Anaptychia.
Anaptychia ciliaris is the type species of Anaptychia. This genus was proposed by Gustav Wilhelm Körber in 1848 as a replacement for the name Hagenia, suggested by Franz Gerhard Eschweiler in 1824, but already being used for a plant genus. Körber described genus Anaptychia as follows (translated from Latin): "Apothecia bordered by a resupinate thallus (ascending thallus is channelled)". Although he did not assign a type species himself, A. ciliaris was later designated as type by Louis Pfeiffer in 1872.
Common names that have been used for Anaptychia ciliaris include "great ciliated lichen" and "eagle's claws".
Subtaxa Several subspecies (subsp.), varieties (v.), and forms (f.) of the lichen have been described; Index Fungorum lists 45 of these subtaxa. This following list is representative, but not exhaustive: f. ciliaris This is the nominate form, in which (asexual fruiting bodies) are rare or absent, and the margins of apothecia are distinctly lacinulate (i.e., fringed or tattered). f. agropia In this form, pycnidia are rare or absent, and the margins of apothecia are (scalloped) or almost entire (i.e., smooth and not lobed or toothed). f. verrucosa In this form, pycnidia are numerous; the (small wart-like protuberances) are the same colour as the thallus or somewhat darker. f. melanosticta In this form, pycnidia are numerous; the verrucae are dark brown to blackish brown. f. nigrescens In this form the laciniae are less than 2 mm wide. subsp. mamillata Compared to the nominate variety, subsp. mamillata has narrower lobes (about 2 mm wide), and a colouration that ranges from dark grey to brown when dry, to dark-olive green when wet, and its lacks and pruina on the thallus surface. var. melanosticta This variety is dark brown with a sparsely hairy upper surface and is mainly found on seaside rocks, especially rocks visited by birds.
In 1962, Kurokawa identified five forms of Anaptychia ciliaris. However, by 1973, he believed these distinctions were merely variations caused by different environmental conditions, thus deeming them taxonomically insignificant. He subsequently grouped them as synonyms. This perspective is shared by Species Fungorum, which does not recognize these subtaxa as having individual taxonomic importance and categorizes them under a collective synonymy. Most of these classifications have not been assessed using contemporary molecular phylogenetics. One exception is A. ciliaris var. melanosticta from coastal regions. DNA analysis revealed it might be distinct enough to be considered its own species, as it emerged as a sister taxon to other tested A. ciliaris samples.
Description
The growth form of Anaptychia ciliaris merges characteristics of both foliose (leafy) and fruticose (bushy) lichens. Like many fruticose species, this lichen attaches to its at a single point. Its fronds, akin to of foliose lichens, lie close to the substrate with distinct upper and lower structures in a dorsiventral organization. This structure comprises an upper fibrous of tightly packed hyphae and an with interspersed between the cortex and the medulla's looser hyphae. Its lower cortex is made of hyphae that are aligned more or less parallel to the surface. The lichen's upper surface is greyish, and the underside can be greyish or whitish, with both sides turning green when wet.
This lichen forms loose attachments to its substrate, allowing it to develop large colonies up to or more across. These colonies comprise neighbouring individuals each with elongated, linear structures () that repeatedly branch (into roughly equal parts). The laciniae generally have an upward, somewhat ascending orientation. Their width is up to about , and they are about 300 μm thick. They appear either flat or somewhat convex and are covered in soft, fine hairs (). The fibrous outer cortex imparts structural strength to the laciniae, helping them maintain an upright orientation. Numerous pale, lateral lie along the margins of the laciniae. They are dark grey to black and up to long. Sometimes, these long cilia form —specialized aerial attachment organs with highly adhesive hyphae. Upon contact with nearby surfaces, often another lobe of its own thallus, these hapters induce branching and create a spreading sheath, leading to entanglement.
On the undersurface of the laciniae, the thallus lacks a cortex and appears paler than its upper surface. The lower surface features irregular and is adorned with rhizines (root-like attachment structures) along the margins, which are the same colour as the thallus. These rhizines measure between in length and may be either or occasionally branched towards the tips. The upper cortex of the laciniae has irregular thickening, and its lower surface has contours, occasionally extending downward to the lower surface of the thallus. The , housing cells measuring 10–15 μm in diameter, is frequently interrupted by the upper cortex, resulting in a discontinuous pattern. The medullary layer is typically very thin and may even be in some regions.
Apothecia, the reproductive structures, are found on the thallus. These structures are usually (spread over the thallus surface), and either stipitate (with a stipe) or somewhat (directly on the thallus). Their diameters range from . Their margins are lacinulate (tattered), with ciliate lacinules along the edges. The of the apothecia is brown or dark brown, initially covered in a white that may fade. The receptacle's hymenium, 150–200 μm tall, turns blue when stained with iodine. Its cortex is irregularly thickened and resistant to iodine staining. The cylindrical or asci measure about 120 by 30 μm and usually contain between four and eight spores. Spores are dark brown, ellipsoid with rounded tips, and somewhat constricted at the centre. They measure 17–23 by 28–43 μm, with thin, uniformly thickened walls. Initially, spores are oval, and filled with and mucous substances. Eventually, a central partition (septum) forms, dividing the contents and leading to a two-cell state.
No lichen products have been identified from Anaptychia ciliaris, and it does not react with any of the standard chemical spot tests used to help identify lichens.
The morphology of A. ciliaris changes when exposed to adverse concentrations of ambient levels of air pollutants. It stops producing cilia, and the lobes become shorter and develop a warty upper surface.
Photobiont The green algal species Trebouxia arboricola was the first photobiont of Anaptychia ciliaris to be identified. A concurrent study corroborated this association and suggested the nonspecific nature of A. ciliaris in incorporating algae from adjacent lichens. The A. ciliaris specimen studied was sourced from tree bark near Xanthoria parietina and Pleurosticta acetabulum. The internal transcribed spacer ribosomal DNA of the photobiont closely matched the sequences from the photobionts of these neighbouring lichens, suggesting they share the same algae. Anaptychia ciliaris undergoes sexual reproduction through the production of meiotic spores. In lichens, this reproductive mode disperses individual symbionts separately, leading to new symbiotic formations. Such a process facilitates genetic diversity and potential symbiotic shifts among different species.
In 2014, a different member of Trebouxia was shown to partner with Anaptychia ciliata. Trebouxia decolorans is a common and widespread symbiotic haploid green alga known for forming symbiotic associations with various lichen-forming fungi. Microsatellite primers, designed specifically to probe the genetic structure and diversity of this photobiont, were used to elucidate the intra-thallus genetic diversity of T. decolorans. This revealed the presence of multiple, genetically distinct photobiont strains within the thalli of the fungi. Particularly in A. ciliata, the predominant source of photobiont diversity seems to be intrathalline somatic mutations, possibly due to the longer lifespan of the fungus compared to the mycobiont, allowing ample time for mutations to accumulate.
Similar species The moss-dwelling African species Anaptychia ethiopica closely resembles A. ciliata, so much so that its authors consider it a sorediate version of that species. It is only known to occur in the mountains of Ethiopia at altitudes over .
Habitat and distribution