Description
Myriolecis species grow as thin, crust-like patches that are usually sunk into the surface they inhabit, whether that is rock, bark or soil. Where the thallus (the lichen body) protrudes, it can crack into tiny island-like plates called areoles or break up into scattered granules , but it never forms the powdery eruptions known as soredia, the finger-like projections called isidia or the cyanobacterial swellings termed cephalodia. The photosynthetic partner is most often a single-celled green alga from the genus Trebouxia , although closely related algae may substitute in some species. [5]
The sexual fruit-bodies (apothecia) sit directly on the thallus and are occasionally lifted on a very short stalk. Each disc starts with a conspicuous rim of thallus tissue that is white or matches the thallus colour; this margin may become wavy or disappear as the apothecium ages. A distinct supporting wall ( true exciple ) is largely absent, but the disc's surface layer ( epithecium ) carries brown pigments that can clump into tiny grains. Beneath this, the spore-bearing layer (hymenium) is almost colourless and stains blue when treated with iodine, confirming the Lecanora -type ascus—a slender club that typically contains eight colourless, one-celled ascospores with smooth, sometimes thickened walls. Minute, flask-shaped pycnidia embedded in the thallus produce asexual spores: tiny rods that may be straight, curved or sickle-shaped. Across the genus, chemical composition is variable; individual species manufacture different suites of lichen products—depsides, depsidones, terpenoids or xanthones—that can help in species identification. [5]
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