Myriospora

Myriospora is a genus of crustose (crust-like), rock-dwelling lichens in the family Acarosporaceae. Its small, often mosaic-cracked thalli bear minute, blackish fruiting discs that each release dozens of colourless spores, a feature alluded to by the genus name—which means "countless spores". Following a 2024 transfer of Acarospora molybdina into the group, around thirteen species are accepted; the type species, M. smaragdula, is a common emerald-tinged "rock scale" on sun-exposed stone across the Holarctic realm. The genus was proposed in 1853 as a segregate of Acarospora but the original description fell short of the formal rules then in force. Wilhelm Uloth supplied a validating description in 1861, yet for more than a century lichenologists kept the group within Acarospora. Molecular studies in the early 2000s showed that the so-called A. smaragdula complex forms its own evolutionary lineage; competing names (Silobia, Trimmatothelopsis) were put forward, but in 2012 Arcadia and Knu......read more on Wikipedia.