Heterogynaidae is a minor and disputed lineage (only eight described

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

in a single genus, ''Heterogyna'') of small spheciform wasps occurring in

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

Botswana Botswana (, ), officially the Republic of Botswana ( tn, Lefatshe la Botswana, label= Setswana, ), is a landlocked country in Southern Africa. Botswana is topographically flat, with approximately 70 percent of its territory being the Kalaha ...

Turkmenistan Turkmenistan ( or ; tk, Türkmenistan / Түркменистан, ) is a country located in Central Asia, bordered by Kazakhstan to the northwest, Uzbekistan to the north, east and northeast, Afghanistan to the southeast, Iran to the sout ...

Oman Oman ( ; ar, عُمَان ' ), officially the Sultanate of Oman ( ar, سلْطنةُ عُمان ), is an Arabian country located in southwestern Asia. It is situated on the southeastern coast of the Arabian Peninsula, and spans the mouth of ...

, the

United Arab Emirates The United Arab Emirates (UAE; ar, اَلْإِمَارَات الْعَرَبِيَة الْمُتَحِدَة ), or simply the Emirates ( ar, الِْإمَارَات ), is a country in Western Asia ( The Middle East). It is located at t ...

, 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 Brachyptery is an anatomical condition in which an animal has very reduced wings. Such animals or their wings may be described as "brachypterous". Another descriptor for very small wings is microptery. Brachypterous wings generally are not functi ...

, 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 In evolutionary ecology, a parasitoid is an organism that lives in close association with its host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionary strategies within parasi ...

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

metasoma The metasoma is the posterior part of the body, or tagma, of arthropods whose body is composed of three parts, the other two being the prosoma and the mesosoma. In insects, it contains most of the digestive tract, respiratory system, and circul ...

tergum A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'ma ...

VI and gonostyli may represent a unique prey transport mechanism, but this is also unconfirmed. The Heterogynaidae were historically considered the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to the remainder of the

Apoidea The superfamily Apoidea is a major group within the Hymenoptera, which includes two traditionally recognized lineages, the " sphecoid" wasps, and the bees. Molecular phylogeny demonstrates that the bees arose from within the traditional " Crabroni ...

, but recent studies utilizing molecular characters do not support this hypothesis. While

monophyly In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...

of the genus is strongly supported, it is now considered to be related to the

Crabronidae The Crabronidae are a large paraphyletic group (nominally a family) of wasps, including nearly all of the species formerly comprising the now-defunct superfamily Sphecoidea. It collectively includes well over 200 genera, containing well over 9 ...

or, most recently, a lineage within the Bembicidae.Manuela Sann, Oliver Niehuis, Ralph S. Peters, Christoph Mayer, Alexey Kozlov, Lars Podsiadlowski, Sarah Bank, Karen Meusemann, Bernhard Misof, Christoph Bleidorn and Michael Ohl (2018) Phylogenomic analysis of Apoidea sheds new light on the sister group of bees. ''BMC Evolutionary Biology'' 18:71.

References

* *Goulet, H., Huber, J.T. (1993) Hymenoptera of the World. Agriculture Canada Research Branch, publication 1894/E. 668pp. *Ohl, M. & Bleidorn, C. (2006) "The phylogenetic position of the enigmatic wasp family Heterogynaidae based on molecular data, with a new description of a new, nocturnal species (Hymenoptera: Apoidea)". ''Systematic Entomology'', 31, 321–337. Apoidea genera {{Apoidea-stub