Heterogynaidae is a minor and disputed lineage (only eight described

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

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

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, the

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, and the

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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 A fossorial animal () is one that is adapted to digging and which lives primarily (but not solely) underground. Examples of fossorial vertebrates are Mole (animal), moles, badgers, naked mole-rats, meerkats, armadillos, wombats, and mole salamand ...

parasitoids In evolutionary ecology, a parasitoid is an organism that lives in close association with its host (biology), host at the host's expense, eventually resulting in the death of the host. Parasitoidism is one of six major evolutionarily stable str ...

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 (biology), 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 sy ...

tergum A ''tergum'' (Latin for "the back"; : ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton wi ...

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 (of over 30 000 species) within the Hymenoptera, which includes two traditionally recognized lineages, the "sphecoid" wasps, and the bees. Molecular phylogeny demonstrates that the bees arose from ...

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

monophyly In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria: # the grouping contains its own most recent comm ...

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

Crabronidae The Crabronidae is a large family of wasps within the superfamily Apoidea. Taxonomy and phylogeny This family has historically been treated as a subfamily in the now-defunct Spheciformes group under the family Sphecidae. The Spheciformes inclu ...

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