Species of lichen
 ;templatestyles src="Template:Taxobox/core/styles.css" / ;
Collemopsidium sublitorale is a species of lichen in the family Xanthopyreniaceae. First described in 1871, it forms a "borderline" symbiotic relationship with cyanobacteria that is less structured than typical lichen partnerships. The species is characterised by an immersed thallus and black, roughly spherical fruiting bodies measuring 0.15–0.55 mm in diameter. It grows in the intertidal and littoral fringe zones of marine environments, exclusively on calcareous substrates such as limestone and marine shells. Studies have documented its presence along both exposed and sheltered coastlines in northwest Europe, where it typically occurs in shaded positions lower in the tidal zone.
Taxonomy.
It was first scientifically described by William Allport Leighton in 1871; he initially classified it in the genus "Verrucaria". He described it from specimens found growing on limpet shells ("Chthamalus stellatus") on submerged maritime rocks, and considered it a rare species. After having been transferred to the genera "Arthopyrenia", "Thelidium", "Pyrenocollema" in various times in its taxonomic history, Martin Grube and Bruce Douglas Ryan reclassified it to "Collemopsidium" in 2002, giving it its current name.
Molecular phylogenetics analysis of ITS1 rDNA sequences has confirmed "C. sublitorale" as a distinct monophyletic species. Studies of specimens from both Ireland and Norway have shown that the species maintains consistent genetic and morphological characteristics across its range, despite showing some variation in perithecial size. The species shows clear genetic separation from other marine "Collemopsidium" species, including "C. halodytes" and "C. foveolatum", even when growing alongside them on the same substrate.
Molecular phylogenetic studies published in 2016 established that "C. sublitorale" and other members of the genus "Collemopsidium" belong to the order Collemopsidiales within Dothideomyceta. This order was created to accommodate these marine borderline lichens after genetic analysis showed they formed a distinct lineage that originated around 230 million years ago during the Triassic period. The emergence of these marine lichens coincided with more arid conditions following the Permian-Triassic mass extinction event.
The German vernacular name for this species is , which roughly translates to "shore glue-kernel lichen", reflecting both its coastal habitat ( meaning shore) and its reproductive structures ( referring to its kernel-like perithecia).
Description.
"Collemopsidium sublitorale" forms what is known as a "borderline lichen" symbiosis – a relatively loose association with cyanobacteria that is less structured than typical lichen partnerships. It is characterised by an entirely ;dfn id="" ;immersed ;/dfn ; thallus with the ;dfn id="" ;photobiont ;/dfn ; occurring in scattered groups or sometimes absent. Its ;dfn id="" ;perithecia ;/dfn ; (fruiting bodies) measure 0.15–0.55 mm in diameter and are usually ;dfn id="" ;sessile ;/dfn ; and roughly spherical ( ;dfn id="" ;globose ;/dfn ;, featuring a conical, black, hemispherical ;dfn id="" ;involucrellum ;/dfn ; that spreads laterally. The perithecia can also be semi-immersed with a flatter, spreading involucrellum. The ;dfn id="" ;ascospores ;/dfn ; measure 15–25 by 5–10 μm. The species produces pycnidia that can range from common to absent, which are either immersed or semi-immersed with a black, flattened involucrellum. Larger pycnidia can be similar in size to smaller perithecia.
Habitat and distribution.
"Collemopsidium sublitorale" is found in the intertidal and littoral fringe zones of marine environments, where it grows primarily on calcareous substrates including limestone and the shells of marine organisms. Unlike some related species that can grow on siliceous rock, "C. sublitorale" is restricted to calcareous surfaces. Studies from northwest Europe have documented its presence along both exposed and sheltered coastlines. The species has been found to occupy a relatively narrow ecological range compared to other members of the genus, typically occurring lower in the tidal zone. It shows a preference for more shaded positions on the shore, though it can tolerate various levels of sun exposure. Research from coastal sites in Norway and Ireland has shown that while the species can be found across different wave exposure levels, it maintains consistent substrate preferences regardless of local conditions. While widely distributed along the North Sea coast of Germany, "C. sublitorale" is considerably less common than its relative "C. foveolatum" in this region.
References.
 ;templatestyles src="Reflist/styles.css" / ;