Megarhyssa rixator (Schellenberg, 1802)

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 : 114

Megarhyssa rixator (Schellenberg, 1802) (Fig. 60)

Megarhyssa spp. are huge parasitoids of Siricidae (Symphyta) . The females have important adaptations for their long ovipositor, for example grooves on the hind coxae and a membranous sac at the position of the apical sternites ( QUICKE, 2015). All four western European Megarhyssa -species have recently colonized the Low Countries and are now fully present and reproducing ( VERHEYDE et al., 2020a).

M. rixator was the last species to be reported in the Low Countries. Furthermore, it is the only species associated with conifers (as the larvae of their hosts live there). It can be distinguished from R. persuasoria (Linnaeus, 1758) by its mesoscutum (often with two white lines). Its metasoma has white cylindrical or rectangular stains laterally, instead of smaller more roundish spots (Fig. 60). The apical tergites have a different shape, with the abovementioned membranous sac visible when females are ovipositing.

First report for Belgium and the Netherlands.

MATERIAL EXAMINED:

BELGIUM: • 1 ♀; Geel , Belsbroekbos (AN); 51°09’25”N 5°04’18”E; 26/v/2017; J. Eykmans leg.; field observation; K. Zwakhals det. (ObsID: 139115219) . • 1 ♂; Bonheiden (AN); 51°01’15”N 4°31’57”E; 12/v/2019; W. Deleus leg.; field observation; F. Verheyde det. (ObsID: 172136425) . • 1 ♀; Dessel , Achter Grootbosheide (AN); 51°16’10”N 5°10’30”E; 22/v/2019; J. De Witte leg.; field observation; F. Verheyde det. (ObsID: 172879635) . • 10 ♀♀; Beernem , Bossen Lindeveld (WVL); 51°06’44”N 3°19’04”E; 26/v/2020; A. De Ketelaere & L. Lams leg.; coll. ADK; field observation, oviposition on Pinus sylvestris ; A. De Ketelaere & F. Verheyde det. (ObsID: 192789472) . • 1 ♀; Oud-Turnhout , Landschap De Liereman (AN); 51°19’37”N 5°01’19”E; 9/vi/2020; G. Loos leg.; coll. GL; field observation; F. Verheyde det. (ObsID: 197942234) […] .

THE NETHERLANDS: • 1 ♂; Monfort (LIN); 51°07’42”N 5°56’14”E; 7/v/2018; H. Schmitz leg.; field observation; F. Verheyde det. (ObsID: 156087791) . • 1 ♀; Eindhoven , Stratumse heide (NB); 51°24’26”N 5°30’14”E; 24/v/2019; R. Aussems leg.; field observation; F. Verheyde det. (ObsID: 173604105) . • 1 ♀ 1 ♂; Ede , Noord Ginkel / Zandbosch (GE); 52°02’17”N 5°45’24”E; 27/v/2019; J. Groenleer leg.; field observation in copula; F. Verheyde det. (ObsID: 183266327) . • 1 ♂; Tilburg , De Sijsten (NB); 51°32’40”N 5°00’40”E; 3/v/2020; R. van den Broek leg.; field observation; F. Verheyde det. (ObsID: 190335658) . • 6 ♀♀; Eindhoven , Stratumse heide (NB); 51°24’26”N 5°30’14”E; 7/v/2020; F. Neijts leg.; field observation, oviposition on Pinus sp. ; F. Verheyde det. (ObsID: 190677110) […] .