Diadegma cinnabaritor Aubert, 1970

Verheyde, Fons, Hoekstra, Paul, Libert, Pierre-Nicolas, Meijer, Hilco, Ketelaere, Augustijn De, Vandaudenard, Thibaud, Belgers, Dick & Brosens, Edwin, 1880, Two hundred and five ichneumonid wasps reported for the first time in Belgium and the Netherlands (Hymenoptera: Ichneumonidae), Belgian Journal of Entomology 122, pp. 1-142 : 37-38

Diadegma cinnabaritor Aubert, 1970 (Fig. 10 A–C)

One of the rarest and more surprising findings in this study. Based on the remarkable red habitus, it was first identified as Chromoplex picticollis (Gravenhorst, 1829) . This monotypic genus has a rather long (hind) tibial spur, red mesosoma and metasoma with black ovipositor sheaths and yellow marks on its black face. Its speculum is smooth (HORSTMANN, 1986). However, closer examination of our specimen revealed some divergent characteristics. For example, the hind tibiae were not brown with a medial white band and the spot on the face was rather red than yellow (HORSTMANN, 1986; MOHAMMADI-KHORAMABADI et al., 2017; see Fig. 10A–B). It was thus considered to be a Diadegma sp. ( TOWNES, 1970b). The extend of the testaceous colouration (both mesosoma and metasoma) is unique within the genus.

AUBERT (1970) described the species. It is closely related to Diadegma grisecens (Gravenhorst, 1829) , which is known to be present in Belgium and the Netherlands. HORSTMANN (1973) even assumed it could be a rufous form of this species. The female holotype from Auberts collection (see KLOPFSTEIN & BAUR, 2011) was carefully compared to our specimen by Seraina Klopfstein and it looks nearly identical. This suggests it is a valid species, as it is accepted now, although future genetic analysis will provide a more decisive judgment. Next to the colouration, other characteristics (although variable) to distinguish D. cinnabaritor from D. grisescens are its speculum (shiny, as mentioned above) and its area superomedia (one and a half times as long as wide and more weakly closed at the apical end; see Fig. 10 C) (HORSTMANN, 1973a). AUBERT (1976) later added that D. cinnabaritor is slightly larger and more robust, with 38 instead of 33 antennal segments. Its head is deemed to be more transverse, the ocelli bigger, distanced from the compound eyes by only just their diameter. The apical margin of its clypeus is densely punctuated. Its malar space is shorter and the mandibles are narrowed apically. Finally, the radial cell is longer and the nervellus is postfurcal.

This specimen was gifted to the first author by the initial observer. He donated it to the Naturhistorisches Museum Basel, where it will be analysed genetically and is integrated in a forthcoming key on Campopleginae . As far as we know, our finding constitutes the third report and specimen of this species in collection, worldwide.

First report for the Netherlands; unreported in Belgium.

MATERIAL EXAMINED:

THE NETHERLANDS: • 1 ♀; Nieuwkoop , Nieuwkoopse Plassen (ZH); 52°08’57”N 4°48’57”E; 3/viii/2016; B. Koese leg.; coll. NMB; malaise trap (28.VII–3.VIII); S. Klopfstein det. (ObsID: 122316512); Fig. 10 A–C .