The earliest Encyrtidae (Hymenoptera, Chalcidoidea)

ABSTRACT

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., ♂, surrounded by extant Encyrtidae females.

GRAPHICAL ABSTRACT

KEYWORDS:

• Encyrtidae
• Chalcidoidea
• Eocene
• Sakhalinian amber
• cerci
• filum spinosum

Acknowledgments

I am sincerely grateful to Alexander P. Rasnitsyn (PIN), Alexander G. Radchenko (SIZK), Kateryna V. Martynova (SIZK), Evgeny E. Perkovsky (SIZK), and Lars Vilhelmsen (ZMUC) for discussion, valuable comments, improving English and the material provided, and to Sarah C. Crews (California Academy of Sciences) for final editing of the English text.

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Funding

The study was supported by the National Research Foundation of Ukraine grant “Leading and Young Scientists Research Support” (registration number 2020.02/0369).