Leptochidium Massalongia Polychidium Massalongiaceae is a small family of lichen-forming fungi in the order Peltigerales.

Species in this family have cyanobacteria as their primary symbiotic partner (cyanobiont), so they belong to the group known as "cyanobacterial lichens".

Molecular phylogenetic analysis showed that the three genera formed a well-supported monophyletic group that was distinct from other similar families in the Peltigerales.

The ascomata are in the form of apothecia, and they are usually biatorine (where the outer layers of the apothecium are light-coloured and contain no algae).

The hamathecium (a collective term for all kinds of hyphae or other tissues between asci) consists of unbranched to branched paraphyses, and is amyloid.