Anzia is a genus of foliose lichens known as black-foam lichens in the large family Parmeliaceae. It was formerly included in the monogeneric family Anziaceae, but this has since been subsumed into the Parmeliaceae.
The genus name of Anzia is in honour of Martino Anzi (1812-1883), an Italian botanist and professor of theology from Como.[1]
The genus was circumscribed by Ernst Stizenberger in 1862, with Anzia colpodes assigned as the type species. This lichen was originally described as Lichen colpodes by Erik Acharius in 1799.
In 1932, Yasuhiko Asahina divided the genus into three sections (Simplices, Duplices, and Nervosae) based on the structure of the medulla. When Isao Yoshimura later observed that Anzia japonica had two medulla types in a single species (i.e. both a single-layered and a double-layered medulla), he combined sections Simplices and Duplices into section Anziae.
Members of Anzia have a foliose growth form, with a thallus that can measure anywhere from 2– wide. The narrow lobes that comprise the thallus are pale greyish white to greyish green in colour. It is one of the only groups in the family not to have eight spores in each ascus, but instead has numerous spores in each ascus (varying slightly from ascus to ascus). These ascospores are crescent shaped. A characteristic of the genus is the presence of a brown-black or pale brown spongy cushion called a spongiostratum, which covers the lower surface.
Pannoparmelia also has a spongiostratum, but in this genus the asci contain eight ascospores, and the upper cortex is yellow-green.
The genus has a cosmopolitan distribution, but is concentrated in the Northern Hemisphere, particularly in Japan.
A fossilized Anzia, Anzia electra, was found in 35–40 Myr-old Baltic amber. Its features suggest that the main distinguishing characteristics in the thallus morphology of section Anzia have been retained for tens of millions of years.