Mesochorus sedis 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 : 13-14

23. Mesochorus sedis SCHWENKE, 1999

( Figs 22a–d )

Holotype: "() Rosslau 4,5 km NNO 1992 144/92 H. Zoerner; Fläming, feu. Waldwege" [, no. 144/92, Germany: Saxony-Anhalt, Fläming, 4.5 km NNE of the district Rosslau of town Dessau-Rosslau, moist forest trails, 1992, leg. K.H. Zoerner] ( SDEI).

Description: Missing: Right antenna completely. Body length 2.9 mm. Flagellum with 26 flagellomeres, preapical flagellomeres ca. 2.0x longer than wide; 1 st flagellomere 5.8x longer than wide and 0.7x as long as the eye; 2 nd flagellomere 3.9x longer than wide. Temple roundly narrowed behind the eye, 0.5x as long as the eye width. OOD 1.0. Face narrow, with fine dense punctures and distinct central ridge, 0.9x as wide as the length of clypeus+face and 0.73x as wide as the length of eye, sides slightly convergent ventrally. Clypeus with rather dense punctures. MI 0.4. Malar space and ventral 0.5 of facial orbit striate. Mandible with two equal teeth. Genal carina reaching the hypostomal carina far from mandibular base. Mesoscutum with fine scattered punctures; mesopleuron with fine punctures dorsally, almost smooth ventrally; metapleuron with superficial and scattered punctures. Area basalis trapezoid, wider than long; area superomedia 1.6x longer than wide and 0.8x as long as the area petiolaris, costula in the middle; area petiolaris very large, almost 0.5x as long as propodeum and 1.25x longer than wide. Hind femur 5.3x longer than wide; hind metatarsus short, 0.35x as long as the hind tibia; hind clwas without visible teeth. Areolet stalked, 2 nd recurrent vein slightly distal to its middle; nervulus interstitial; pterostigma 3.2x longer than wide, radial vein in its distal 0.55, distal part of radial vein long and weakly sinusoid. 1 st tergite 2.7x longer than wide; postpetiolus 1.5x longer than wide, with some rugae; 2 nd tergite 1.1x longer than wide; thyridium comma-shaped. Stylet stab-shaped, clubbed apically, 1.6x longer than the 2 nd hind tarsomere.

Colour: Face and orbits reddish-yellow; ocellar field and occiput dorsally brownish. Mesosoma reddish; hind edge of pronotum, tegula and wing base yellow; mesoscutum with two lateral and one frontomedial reddish-brown spots. 1 st tergite yellow-red, centrally brownish; 2 nd tergite brown, yellow in the apical 3/10 of tibial length; 3 rd tergite yellow, brownish in the apical 1/3; following tergites brown, with wide grey apical bands (slightly vespoid). Legs pale yellow; hind tibia not distinctly darkened apically. Pterostigma hyaline, apical margin ochreous.

Remark: The correct position of this species is questionable. SCHWENKE (1999) included Mesochorus sedis in the curvulus- group, but the ocelli are large and the distal part of radial veins only slightly sinusoid. In my opinion, it is better placed in the pectoralis -group. In the key for the males ( SCHWENKE, 1999: 115–118) it runs to no. 34 ( Mesochorus subfuscus SCHWENKE ), but differs from that species by its smaller size, rugose postpetiolus, and different colour of the metasoma.

Figures

Fig. 22a-d: Holotype of Mesochorus sedis SCHWENKE:a. face; b. mesosoma; c. metasoma; d. stylet.