[2] Proposed by Dutch lichenologist Harrie Sipman in 1983, the genus is characterised by its thick, ecorticate thallus ranging from pale whitish-grey to yellowish, and its disc-like fruiting bodies (apothecia) that can be biatorine or lecideine.

Megaloblastenia lichens form a symbiotic relationship with Dictyochloropsis algae, produce hyaline, bicellular ascospores with polaribilocular structure, and contain chemical compounds such as zeorin, pannarin, or usnic acid.

Found in Australasia and South America, these lichens typically grow as epiphytes on trees in moist forests within temperate to tropical oceanic climates.

The asci have a distinctive blue-staining outer layer and a well-developed blue tholus (a thickened region at the tip), but lack internal divisions.

[5] Confined to oceanic climates in temperate to tropical regions of Australasia and South America, Megaloblastenia species typically grow as epiphytes on trees in moist forests.