| Hymenopterans, Stenotritidae, Sierolomorphidae, Ampulicidae, Scolebythidae|Heterogyna Wikipedia
Heterogynaidae is a minor family (only eight described species in a single genus, Heterogyna) of small spheciform wasps occurring in Madagascar, Botswana, Turkmenistan, Oman, the United Arab Emirates, and the Eastern Mediterranean area. The majority are dark in color and range in size from approximately 1.5 to 5.0 mm. Most specimens have been collected in arid climates, but one species from Madagascar is known to occur in a humid forest habitat. Although males have functional wings, heterogynaid females are typically brachypterous, a trait which is unique among spheciform wasps. Wing venation is reduced in both sexes. All species are diurnal, with the exception of H. nocticola. Other aspects of their biology are completely unknown, but details of their morphology have prompted researchers to hypothesize that they may be non-fossorial parasitoids adapted to hunt in tight spaces, such as under tree bark. This is speculative and has not yet been confirmed by actual observations of behavior. It is also possible that modifications of the female metasomal tergum VI and gonostyli may represent a unique prey transport mechanism, but this is also unconfirmed.
The Heterogynaidae are generally considered the sister taxon to the remainder of the Apoidea. However, the results of recent studies utilizing molecular characters suggest that this hypothesis may be incorrect. A preliminary study by Ohl and Bleidorn (2006) suggested that the heterogynaids arose from within the Crabronidae, but a later study by Debevec et al. (2012) showed very weak support for this hypothesis. Their results much more strongly suggested that the Heterogynaidae are the sister taxon to a clade composed of the Sphecidae, the Crabronidae, and the Anthophila. Monophyly of the family is strongly supported.