Megymenum

Megymenum is a genus of Asian and Australian shield bugs in the family Dinidoridae and typical of the subfamily Megymeninae. It was erected by Félix Édouard Guérin-Méneville in 1831 and species have been recorded from India through to Japan, Indochina, Malesia, New Guinea and Australia.

==Description== 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.