Vulgichneumon trifarius (Berthoumieu, 1892)

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 : 77-78

Vulgichneumon trifarius (Berthoumieu, 1892) (Fig. 39 A–B)

Vulgichneumon is a complex genus within Ichneumonini , which is sometimes difficult to discern from the closely related genus Virgichneumon . In contrast to the latter genus, the gastrocoeli are very small, sometimes punctiform or obsolete. The thyridia are less deeply impressed in Vulgichneumon ( VALEMBERG, 1983) and the central part of the postpetiole is somewhat less densely punctuated. Many species are sexually dimorph.

Both females and males (which are not well known) closely resemble Ichneumon oblongus Schrank, 1802 . The main differences lay in the abovementioned characteristics for the genus, the propodeal carination and in the colouration of the scutellum, which is white in V. trifarius . Vulgichneumon trifarius has a closely punctuated and matt frons ( RASNITSYN & SIITAN, 1981). Otherwise the female species have many similarities: tricoloured antennae, last two apical tergites with white dots, head and mesosoma black, metasoma reddish and black. Even the hind femora and the hind tibiae, which are red with an apical black band, are identical (Fig. 39 A). We also collected several male specimens (Fig. 39 B). They measured approximately 6.5 mm, had 28 flagellomeres and tyloids on flagellomeres 4–11. Coloured rings on the antennae were missing. These numbers are very similar to those for Ichneumon oblongus . Hilpert mentions 26–30 flagellomeres with tyloids on 5–11(12) (HILPERT, 1992). More research is necessary to confirm the status of this species (and those of the males). It seems to be rather common and clearly flies late in the year (October-November). One host is known: the common lepidopteran Bupalus piniaria (Linnaeus, 1758) ( Lepidoptera : Geometridae ) ( MEYER, 1933).

First report for Belgium and the Netherlands.

MATERIAL EXAMINED:

BELGIUM: • 1 ♀; Sint-Lambrechts-Herk, Mombeekvallei ( LIB); 50°53’16”N 5°19’47”E; 19/xi/2010; K. Windmolders leg.; field observation; J. Valemberg det. (ObsID: 50995879) . • 9 ♂♂; Sint-Andries , Ter Heyde (WVL); VII–X.2016; W. Dekoninck et al. (KBIN) leg.; coll. KBIN/RBINS (project Bruges heathlands); yellow pan trap & pitfall trap; F. Verheyde det. ; Fig. 39 B . • 1 ♀; Tessenderlo , Averbode Bos en Heide ( LIB); 51°02’40”N 5°00’04”E; 11/x/2018; G. Van den Heuvel leg.; light trap; F. Verheyde det. (ObsID: 163626762) . • 1 ♀; Zedelgem , Militair domein Vloethemveld - Relict natte heide (WVL); 25/x/2019; W. Dekoninck et al. (KBIN) leg.; coll. KBIN/RBINS (project Bruges heathlands); pitfall trap (11-25); F. Verheyde det. • 1 ♀; Koksijde , Doornpanne (WVL); 51°06’59”N 2°39’11”E; 15/xi/2020; A. Beidts leg.; coll. ADK; light trap; A. De Ketelaere det. (ObsID: 203249317) ; Fig. 39 A .

THE NETHERLANDS: • 1 ♀; Bergen (NH); 52°40’02”N 4°42’21”E; 11/x/2014; T. de Graaf leg.; field observation; F. Verheyde det. (ObsID: 89137865) . • 1 ♀; Veenendaal , Kwintelooyen (UT); 51°59’32”N 5°33’03”E; 21/x/2016; J. Bouwmans leg.; field observation; F. Verheyde det. (ObsID: 125768011) . • 1 ♀; Arcen , Walbeckheide (LIN); 51°30’47”N 6°11’41”E; 12/iii/2020; J. Bouwmans leg.; field observation; F. Verheyde det. (ObsID: 186502407) . • 1 ♀; Zwolle , Westerveldse Bos (OR) ; 52°32’47”N 6°05’19”E; 19/viii/2020; G. Reitsma leg.; field observation; F. Verheyde det. (ObsID: 198735413) .