Mesochorus gilvus 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 : 7-8

11. Mesochorus gilvus SCHWENKE, 1999

( Figs 10a–d )

Holotype: "() Guttau Zucht, 4295 Zoerner 7.1976" [, no. 4295, Germany: Saxony, Malschwitz, district Guttau, breeding, 7.1976, leg. K.H. Zoerner] ( SDEI?).

The holotype was studied by K. HORSTMANN some years ago who made some unpublished notes. I tried to locate the holotype but it was not found in SDEI, the ZSM or in the HORSTMANN collection. For the description and figures, I used a paratype from the reared type-series with similar features as noted for the holotype.

Paratype: () Guttau Zucht 4295 Zoerner 22.7.1976 ( ZSM) .

Description: Body length 3.6 mm. Flagellum with 30 flagellomeres; 1 st flagellomere 6.9x longer than wide and 0.85x as long as the eye; 2 nd flagellomere 5.0x longer than wide; preapical flagellomeres ca. 2.0x longer than wide. Temple short and strongly narrowed behind eye, 0.55x as long as the eye width. OOD 1.5. Face with moderately dense punctures, 1.05x wider than the length of clypeus+face and 1.05x wider than the length of eyes. Ventral 0.3 of facial orbit, base of mandible and malar space with fine striation. Mandible with two equally sizerd teeth. MI 0.9. Genal carina joining the hypostomal carina far from mandibular base. Mesoscutum almost completely with fine and scattered punctures; mesopleuron with moderately dense coarse punctures dorsally and ventrally; metapleuron with fine scattered punctures. Area basalis trapezoid, about as long as wide; area superomedia 1.6x longer than wide and 1.1x longer than the area petiolaris; area petiolaris 1.13x longer than wide. Hind femur 4.4x longer than wide; hind metatarsus 0.53x as long as the hind tibia; hind claws small, with 1 distinct basal tooth. Areolet shortly sessile, 2 nd recurrent vein in its middle; nervulus postfurcal (by 2x its width); postnervulus intercepted in its basal 0.3; radial vein reaching the pterostigma at its distal 0.6. 1 st tergite 2.8x longer than wide; postpetiolus 1.2x longer than wide, with some fine rugae; 2 nd tergite 0.88x as long as wide; thyridium transverse. Ovipositor sheath stab-shaped, pilose, ca. 10.0x longer than wide and 1.1x longer than the hind metatarsus, slightly narrowed apically.

Colour: Head yellowish-red; mandibular teeth and ocellar field black; clypeus, gena and inner orbit slightly paler. Mesosoma yellowish-red; mesoscutum with frontal parts of median field and central parts of lateral field pale brownish; propodeum yellowish-red, somewhat darker fronto-dorsally. 1 st tergite black, petiolus yellow basally, postpetiolus narrowly yellowish-red apically; 2 nd tergite black in the basal third, with large arched yellowish mark apically; 3 rd tergite yellowish basally, more reddish apically, following tergites reddish. Legs yellow; hind tibia narrowly dark brownish at apex (1/3 of tibial width); apical tarsomere slightly darkened at apex. Pterostigma very pale ochreous, margins not darkened.

Remark: This species is difficult to identify in the key of the dispar -group ( SCHWENKE, 1999: 48–51) since the ovipositor sheath is slightly longer (1.1x) than the hind metatarsus. In this key, it runs to no. 42 ( Mesochorus velox HOLMGREN ), but differs from M. velox by the different coloration of the 3 rd tergite and the narrower temples.

Figures

Fig. 10a-d: Paratype of Mesochorus gilvus SCHWENKE: a. face; b. mesosoma; c. metasoma; d. ovipositor sheath.