Species in genus
Megymenum have extended or greatly expanded
pronotal margins (as in the
type species M. dentatum) with a rounded
scutellum: characteristic of the Dinidoridae. In most species the second
valvifers are reduced, lightly sclerotised, and fused in the middle. Some species have reduced
hemelytra and are flightless. Female
Megymenum gracilicorne has distinctive sexual dimorphism in the hind legs, and females have a broadened part on the inner hind tibia which was thought to be a tympanal organ (with the ability to hear sound), but in 2025 it was discovered that this organ has a layer of secretory cells and the cavity contains special fungi. These fungi, mostly in the family
Cordycipitaceae, are transferred to eggs at the time of oviposition and the fungus is thought to provide protection to the eggs against parasitic wasps. ==Species==