Mesochorus diluvius SCHWENKE, 1999

Riedel, Matthias, 2018, The types of Mesochorus GRAVENHORST (Hymenoptera, Ichneumonidae, Mesochorinae) described by W. SCHWENKE and deposited in the Senckenberg Deutsches Entomologisches Institut, Beiträge Zur Entomologie = Contributions to Entomology 68 (1), pp. 1-29 : 5

6. Mesochorus diluvius SCHWENKE, 1999

( Figs 6a–d )

Holotype: "() Köthen 46/88 19.5. Zoerner" [, no. 46/88, Germany: Saxony-Anhalt, Köthen , 19.5.1988, leg. K.H. Zoerner] ( SDEI).

Description: Missing: Left flagellomeres from 6 th on, right antenna completely. Body length 4.2 mm. Basal flagellomeres short; 1 st flagellomere 4.6x longer than wide and 0.6x as long as the eye, 2 nd flagellomeres 3.2x longer than wide. Temple roundly narrowed behind eyes, 0.63x as long as the eye width. OOD 1.5. Face coarsely punctate, with parallel sides, about as wide as the length of clypeus+face length and 0.86x as wide as the eye length. Ventral 0.5 of facial orbit and malar space widely striate. MI 0.5. Mandible with two equal teeth. Genal carina reaching the hypostomal carina far from mandibular base. Mesoscutum with rather dense punctures apico-medially and with finer scattered punctures laterally; mesopleuron with fine dense punctures dorsally and very scattered fine punctures ventrally; metapleuron with fine scattered punctures. Area basalis triangular, about as long as wide; area superomedia 1.6x longer than wide and 1.4x longer than the area petiolaris, costula in frontal 4/10 of length of area superomedia; area petiolaris 0.8x as long as wide. Hind femur 4.3x longer than wide; distal fore tarsomere slightly swollen, ca. 2.4x longer than wide; hind metatarsus 0.45x as long as the hind tibia; hind claws with four teeth (2 nd basal tooth longest). Areolet pointed sessile, 2 nd recurrent vein slightly distal to its middle; nervulus interstitial; pterostigma 3.2x longer than wide, radial vein in its distal 0.67. 1 st tergite 2.5x longer than wide; postpetiolus 1.15x longer than wide, smooth; 2 nd tergite 0.86x as long as wide; thyridium roundish. Ovipositor sheath completely pilose, sabre-shaped, 5.5x longer than wide and 1.03x longer than the hind metatarsus, slightly narrowed in the apical 4/10 of tibial length.

Colour: Black. Flagellum yellow-brown. Face blackish; orbit and clypeus reddish-yellow, pale colour widened on vertex. Frons medially, ocellar field and occiput black. Palps, mandible except teeth, gena, hind edge of pronotum, tegula, and wing base yellow. Mesosoma black, mesoscutum with H-sized dark reddish suffusion centrally. Legs reddish-yellow; hind femur with indistinct brownish suffusion; hind tibia yellow, brownish in the apical 2/10 of tibial length (1.5x of tibial width). Tergites blackish; 2 nd tergite with yellow-red band in the apical 2.5/10 of tibial length; 3 rd tergite reddish basally and apically, blackish centrally; following tergites blackish basally and reddish apically. Pterostigmas hyaline-ochreous.

Remark: This species is not placed correctly in the key of the pectoralis -group ( SCHWENKE, 1999: 95–98) since the ovipositor sheath is about as long as the hind metatarsus and the pterostigma is hyaline with a light brownish tint. If the pterostigma is accepted as hyaline, this species would run to no. 10 ( Mesochorus septentrionalis SCHWENKE ) but differs by its brownish face and stouter ovipositor sheath. If the pterostigma is valued as darkened, it runs to no. 92 ( Mesochorus ovimaculatus SCHWENKE ). Comparison of the holotypes of both taxa does not reveal significant differences in morphology and coloration and are synonymized here.

Valid name: Mesochorus ovimaculatus SCHWENKE, 1999 ,

syn. nov. Mesochorus diluvius SCHWENKE, 1999 .

Figures

Fig. 6a-d: Holotype of Mesochorus diluvius SCHWENKE:a. face; b. mesosoma; c. metasoma; d. ovipositor sheath.