Platygastroidea

Family Guides

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Platygastroidea is a superfamily of minute within Hymenoptera, comprising over 4,400 described with an estimated global diversity of approximately 10,000 species. Members range from 0.5 to 12 mm in body length, with most species measuring 1–2.5 mm. The superfamily has been recognized as independent from Proctotrupoidea since 1977 and currently includes eight : Platygastridae, Scelionidae, Geoscelionidae, Janzenellidae, Neuroscelionidae, Nixoniidae, Sparasionidae, and the extinct †Proterosceliopsidae. Fossil records extend from the Early Cretaceous to present.

Damaeus by (c) Alexis Tinker-Tsavalas, some rights reserved (CC BY), uploaded by Alexis Tinker-Tsavalas. Used under a CC-BY license.Epidermoptidae by (c) Cricket Raspet, some rights reserved (CC BY), uploaded by Cricket Raspet. Used under a CC-BY license.Psoroptidae by (c) Oleksii Vasyliuk, some rights reserved (CC BY), uploaded by Oleksii Vasyliuk. Used under a CC-BY license.

Pronunciation

How to pronounce Platygastroidea: /ˌplætɪɡæˈstrɔɪdiə/

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Identification

Distinguished from other Proctotrupomorpha by synapomorphies of the ovipositor structure and details of the mesosoma. Platygastridae can be diagnosed by combination of character reductions including mesofurcal pit and posteriorly shifted origin of first wing flexors. Scelionidae uniquely possess the cranio-antennal muscle, an extrinsic antennal muscle originating from the capsule. Separation from Proctotrupoidea supported by molecular data and morphological characters since 1977.

Images

Appearance

Extremely small , typically 1–2.5 mm in length, with some as small as 0.5 mm and others reaching 12 mm. Body form is highly variable and strongly influenced by : ranges from short and stocky to thin and elongated. Gross morphology (habitus) is diverse across the superfamily.

Habitat

specificity is largely determined by availability rather than . occur in terrestrial environments where their hosts (insect and spider , gall midge larvae) are present. No specific microhabitat requirements documented for the superfamily as a whole.

Distribution

distribution with records from all major biogeographic regions: Afrotropical, Australasian, Nearctic, Neotropical, Oriental, and Palearctic. Documented from British Isles (381 ), Finland (60 species, 52 newly recorded), Canary Islands and Madeira (22 species), Vietnam, New Zealand, Chile, Mexico, and Poland. Fossil evidence from Cretaceous amber (Burmese, other deposits) indicates ancient distribution.

Host Associations

Life Cycle

Development occurs as endoparasitoids within or larvae. Scelionidae and Sparasionidae are idiobiont endoparasitoids of eggs, killing the host immediately. Platygastridae are predominantly koinobiont egg-larval endoparasitoids, allowing host development to continue initially. Specific developmental stages and duration vary by and host association.

Behavior

Solitary . location and oviposition adapted to finding concealed of hosts. Some demonstrate unexpected host range expansion: Idris elba, historically associated with spider eggs, has been documented parasitizing eggs.

Ecological Role

Important regulators of insect and arachnid through . Some utilized as agents. Contribution to dynamics in terrestrial through top-down control of herbivore and populations.

Human Relevance

applications against agricultural pests: some Platygastridae deployed for management of gall midges and whiteflies. Idris elba shows potential for controlling the bagrada bug (Bagrada hilaris) in North America. Research significance in and evolutionary due to Cretaceous fossil record and phylogenetic position.

Similar Taxa

  • ProctotrupoideaHistorically treated as a lineage within Proctotrupoidea; separated by ovipositor synapomorphies and mesosomal characters since 1977
  • ChalcidoideaSimilar minute size and lifestyle; distinguished by wing venation, antennal structure, and mesosomal musculature

More Details

Taxonomic History

Scelionidae was briefly treated as a of Platygastridae, but subsequent analyses restored status. Chen et al. (2021) recognized five new extant families, increasing family-level diversity from three to eight.

Fossil Record

Extends from Early Cretaceous to present. Notable fossils include Archaeoteleia astropulvis (100 million years old, Burmese amber) placed in extant , and Proteroscelio expanding anatomical diversity of extinct genus.

Phylogenomics

Recent phylogenomic studies (e.g., Lahey 2021) using rigorous filtering and likelihood mapping have explored difficult nodes within the superfamily, supporting recognition of Scelionidae and new -level lineages.

Sources and further reading