Diplazontinae Viereck, 1918

Manukyan, Andranik R. & Zhindarev, Leonid A., 2021, Fossil Darwin wasps (Hymenoptera: Ichneumonidae) from Baltic amber, Palaeoentomology 4 (6), pp. 637-647 : 640

Subfamily Diplazontinae Viereck, 1918

( Fig. 2A–H )

Twenty-two recent genera of Diplazontinae are currently recognized in the world fauna, with 355 species described to date ( Broad et al., 2018). Most species have been described from the Holarctic region, with boreal and alpine areas of especially high species richness ( Manukyan, 1995; Klopfstein, 2014). All diplazontines are koinobiont endoparasitoids of aphidophagous Syrphidae (Diptera) . Oviposition occurs into the egg or larva of the host, and emergence occurs from the puparium.

The only fossil species, Lithotorus cressoni Scudder, 1890 , was described from the Green River, and preliminarily placed in Diplazontinae by Townes (1966). However, subsequent research has shown an uncertain taxonomic position of this species ( Spasojevic et al., 2018a). Therefore, there are no confirmed records of fossil Diplazontinae up to the present.

In the collection of KAM, we found a puparium with an emergence hole typical of Diplazontinae ( Fig. 2A, B ). Diplazontinae emerge from the puparium of the host from the head end. The mechanism of cutting through the puparium, the shape of the holes and the semicircular flaps left are similar in all diplazontines ( Rotheray, 1981) (see Fig. 2C–F ), while in other parasitoids of syrphid flies, the cutouts are not semi-circular. Species of the genus Callaspidia Dahlbom ( Hymenoptera , Figitidae ) cut out irregular holes on the lateral surface of the puparium and Cryptinae cut irregularly rounded holes in the center of the dorsal surface ( Fig. 2G ). The gregarious Bothriothorax Ratzeburg , Syrphophagus Ashmead (Encyrtidae) , and Asaphes Walker (Pteromalidae) cut a small hole on the lateral surface of the puparium ( Fig. 2H ), which is then used by all emerging specimens.

Our finding is the first record of subfamily Diplazontinae in the upper Eocene.

Figures

FIGURE 2. A, Puparium of aphidophagous syrphid in Baltic amber (Diptera: Syrphidae: Syrphinae) (KAM No. 6361) with an emergence hole typical for Diplazontinae, ventral view. B, Right lateral view; Emergence holes of various recent parasitoids of aphidophagous syrphids (Diptera, Syrphidae, Syrphinae). C, Diplazon pectoratorius. D, Syrphoctonus sp. E and F, Diplazon laetatorius. G, Cryptinae (gen. et sp. indet). H, Asaphes sp. (Pteromalidae). Scale bars = 1 mm.