Relicina

''Relicina'' is a genus of foliose lichens belonging to the large family Parmeliaceae. It contains 60 species.

Taxonomy

''Relicina'' was originally conceived as a series of the large genus '' Parmelia'' by lichenologists Mason Hale and Syo Kurokawa in 1964. A decade later, they promoted it to the status of genus.

The genus ''Relicinopsis'', proposed by Australian lichenologists John Elix and Doug Verdon in 1986 as a segregate of ''Pseudoparmelia'', was shown to be nested within ''Relicina'' in a 2017 molecular phylogenetics study.

Description

''Relicina'' lichens have a leaf-like (foliose) body (thallus) with flat, two-sided that are typically attached by a somewhat swollen, bulbous base. The edge of each lobe is lined with short, black, hair-like structures called . The upper surface is generally yellow to yellow-green and may sometimes show small spots; it lacks the typical hairs and minute pores (pseudocyphellae) seen in some other lichens. Instead, the surface is covered by a continuous, pored layer (the ). On the underside, the color ranges from pale brown to black, and it bears simple or branched, root-like structures (rhizines) that extend to the edges, helping secure the lichen to its substrate.

The lichen's photosynthetic partner is a green alga similar to those in the genus ''Trebouxia''. Reproduction occurs through apothecia, which are open, disc-like fruiting bodies located on the surface of the lobes. These apothecia have a margin that resembles the thallus (a condition described as ) and display a solid, uninterrupted that ranges in color from pale to dark red-brown. The disc lacks a powdery coating () and is surrounded by a cup-shaped layer. The thallus-like margin is smooth or slightly scalloped and is often fringed with at its base; in some cases, this edge appears almost crown-like due to the influence of swollen and bulbous pycnidia.

Inside the apothecia, delicate filament-like cells called paraphyses are present; these are about 2–3 Î¼m thick, mostly straight, and only lightly branched, with their tips being brown, rounded, and slightly expanded. The spore-bearing sacs, or asci, typically contain eight spores each. Each ascus features a well-developed, iodine-reactive (amyloid) zone known as the that is pierced by a narrow, non-reactive central strand with parallel sides; there is no distinct ocular chamber. The resulting sexual spores are in structure, translucent (hyaline), ellipsoid in shape, and have walls about 0.5 Î¼m thick.

In addition to these sexual structures, ''Relicina'' produces asexual fruiting bodies known as pycnidia. These are embedded in the lichen's surface ( and ) and often appear somewhat swollen. They release conidia—small, asexual spores—that can be spindle-shaped () or more uniformly cylindrical to .

Chemically, members of the genus ''Relicina'' contain usnic acid along with various other secondary metabolites such as depsidones, depsides, or fatty acids.

Species

* '' Relicina abstrusa''
* '' Relicina amphithrix''
* '' Relicina barringtonensis''
* '' Relicina circumnodata''
* '' Relicina clarkensis''
* '' Relicina colombiana''
* '' Relicina conglutinata''
* '' Relicina connivens''
* '' Relicina dahlii''
* '' Relicina demethylbarbatica''
* '' Relicina dentata''
* '' Relicina diederichii''
* ''Relicina eumorpha''
* '' Relicina filsonii''
* '' Relicina intertexta''
* '' Relicina kurandensis''
* '' Relicina limbata''
* '' Relicina malaccensis''
* '' Relicina planiuscula''
* '' Relicina polycarpa''
* '' Relicina rahengensis''
* '' Relicina ramboldii''
* '' Relicina ramosissima''
* '' Relicina relicinula''
* '' Relicina samoensis''
* '' Relicina schizospatha''
* '' Relicina stevensiae''
* '' Relicina subabstrusa''
* '' Relicina subcoronata''
* '' Relicina sublanea''
* '' Relicina subnigra''
* '' Relicina sydneyensis''
* '' Relicina terricrocodila''

References

{{Taxonbar, from=Q7311054

Parmeliaceae
Lichen genera
Lecanorales genera
Taxa described in 1964
Taxa named by Mason Hale
Taxa named by Syo Kurokawa