Nygma
A nygma (plural nygmata) is a spot on the wings of certain insects which have a peculiar dense cuticular structure.
Nygmata are found in caddisflies, scorpionflies, saw-flies and in some families of Neuroptera (e.g. Megaloptera and Ithonidae).
The function of nygmata are unknown: they do not connect with nerves or glands.
Nygmata show up even in fossil Osmylidae from China.
The positions and structure of nygmata are often used in the descriptions of insect species that bear them.
nygmata marked with "ng"