Prasiola Meneghini.

Prasiola is a cosmopolitan genus, which can be found in a wide range of habitats (Broady 1989; Heesch et al. 2012; Rindi et al. 2007) Unlike its relatives, Prasiola forms macroscopic, usually monostromatic thalli of various shapes (ribbon-shaped/sheet-like blades; Fig. 10) and sizes. The cells, arranged in groups of four, contain axial, asteroid chloroplast with one centrally-located pyrenoid. Prasiola reproduces asexually by thallus fragmentation or sexually oogamously (Ettl & Gärtner 2013).

Two of the 34 described species (Guiry & Guiry 2022), P. borealis and P. delicata, enter lichen-like symbiosis with the bipolarly distributed fungus Mastodia tessellata ( Verrucariaceae; Garrido-Benavent et al. 2018). This unusual association, sometimes referred to as ‘borderline-lichen’, gives rise to a thallus, which is formed mainly by the algal partner, whose outer appearance is not changed, but its inner structure is significantly altered (Kováčik & Pereira 2001).

Free-living P. borealis and P. delicata specimens have been collected from coastal rock in Alaska (Garrido-Benavent et al. 2017). In addition, free-living P. delicata was observed in the intertidal of Hokkaido, Japan (Sutherland et al. 2016) and in Kamchatka, Russia (Klochkova et al. 2017).