What's a sceliotracheline? (Hymenoptera, Platygastridae, Sceliotrachelinae)

In 1908, Charles Brues erected the subfamily Sceliotrachelinae for a new, morphologically bizarre genus endemic to South Africa. Since then, 27 genera have been added to the subfamily on the 'hunch' that they all belong to the same monophyletic unit. Masner & Huggert (1989) acknowledged the shortcomings of this classification when they admitted that the main difference between platygastrines and sceliotrachelines was their choice of host, rather than morphological/molecular synapomorphies that support their common ancestry. The purpose of this contribution is to begin answering the question of what a sceliotracheline is, while serving as a primer on the natural history and importance of this ill-defined group of platygastroid wasps.