The earliest Encyrtidae (Hymenoptera, Chalcidoidea)

The data on Encyrtidae of middle Eocene Sakhalinian amber are summarised. Archencyrtus rasnitsyni Simutnik, 2014, Sugonjaevia sakhalinica Simutnik, 2015 and Kotenkia platycera Simutnik, 2015 are redescribed here using supplementary diagnostic features, and high-resolution photos are provided. An additional new genus and species, Encyrtoides pronotatus, gen. et sp.n., is described and illustrated based on a single male. Encyrtids of the middle Eocene differ significantly from both late Eocene and extant ones. The cerci of the new fossil are close to each other and located at the very apex of the gaster. Such a close position of cerci is unknown in either extant or any late Eocene fossil Encyrtidae and is similar to the ground plan of Chalcidoidea. The closing setae (filum spinosum) at the linea calva of the forewing are absent in all known Sakhalinian amber genera, which are preliminarily considered unplaced within Encyrtidae. A comparative morphological analysis of known palaeontological data, including those from the late Eocene fossil record, allowed tracing character changes in some morphological structures in members of the family from the middle Eocene, through the late Eocene, to the present. In the center is E. pronotatus n. gen. and n. sp., male, surrounded by extant Encyrtidae females.

Automated summary

This study summarizes the data on Encyrtidae in middle Eocene Sakhalinian amber, redescribing several species and introducing a new genus and species. The differences between middle Eocene Encyrtids and late Eocene or extant species are highlighted, with a focus on a new fossil species with unique characteristics. Comparative morphological analysis of paleontological data reveals changes in morphological structures of Encyrtidae from middle Eocene to present day.