Enchylium is a genus of lichen-forming fungi in the family Collemataceae. The genus was originally established as a section of the related genus Collema in 1810, but molecular studies have since confirmed it forms a distinct evolutionary lineage. These lichens are characterised by their gelatinous, water-absorbing thalli that swell noticeably after rain and typically colonise bare soil or rock surfaces in well-lit environments. Most species are pioneers that help stabilise loose substrates before other plants and lichens become established.
Taxonomy
Enchylium was introduced as a section of Collema by Erik Acharius in 1810. Acharius characterised this section by its distinctive thallus morphology: imbricate-plicate (overlapping and folded), suborbicular in outline, and composed of minute lobes that become markedly thickened and swollen when moist. This hydration response, where the small lobes dramatically expand when wet, appears to have been a key distinguishing feature that Acharius used to define the section within the broader genus Collema. The taxon was raised to generic rank by Samuel Frederick Gray in 1821. During that action Gray also selected Enchylium tenax (originally published as Lichen tenax) as the type species. A later name, Collemodes Fink (1918), is now regarded as a junior synonym of Enchylium.
Acharius used the name very broadly, and subsequent authors applied it to several unrelated jelly lichens. Modern work restricts the genus to cortex‑less cyanobacterial lichens with relatively small, broadly elliptic ascospore s that favour well‑lit, pioneer habitats on soil or rock. Species of Collema—also without a cortex—differ in having larger, narrower spores and a preference for shadier situations.
A multilocus phylogeny of the Collemataceae confirmed that the "Collema tenax group" forms an independent lineage. To reflect this, Otálora, Jørgensen and Wedin (2014) resurrected Enchylium for that clade and transferred nine formerly...
