The Mymarommatidae are a very small family of microscopic hymenopteran insects. Only 10 living species in one genus have currently been described (others are known only as fossils), but they are known from all parts of the world. Undoubtedly, many more await discovery, as they are easily overlooked and difficult to study due to their extremely small size (most have an overall length of around 0.3 mm).
Virtually nothing is known about the biology of these insects, but because of their size, and simple ovipositors, entomologists assume they are idiobiont parasitoids on the eggs of various insects. They were originally treated as an aberrant subfamily of the chalcidoid family Mymaridae but because of morphological differences, are now usually considered in their own superfamily, Mymarommatoidea, and their similarity to Mymaridae is thought to be a result of convergent evolution.
As taxonomists have examined this group more closely, they have become less certain about which other group of wasps represents the nearest living relatives of the Mymarommatidae. In recent years, some have claimed the nearest relatives are the extinct family Serphitidae, and therefore claim the Mymarommatidae are essentially "living fossils", the sole surviving lineage of an otherwise extinct superfamily Serphitoidea. It remains to be seen whether this change in classification will be accepted, but it has some significant support.