Platystoma species are small flies reaching a length of 4–10 millimeters. The body is black speckled with small whitish or yellowish markings, while the eyes are usually red. They have a quite broad proboscis (hence the Latin name Platystoma, meaning "broad mouth"). The wings are blackish with clear speckles. These flies show a complex mating ritual.
Species belonging to this genus are present in most of Europe, in the eastern Palearctic realm, in the Near East and in North Africa.
The genus is in need of revision to clarify the position of many subspecies that are currently listed. Most of these subspecies were designated by Hennig,[3] but some have been raised to full species since.[4][5] The list below incorporates those names more recently upgraded to species, but leaves the remainder of the subspecies designated by Hennig as subspecies until their position can be rectified by revision.