Mesochorus weigeli, Riedel, 2019

Riedel, Matthias, 2019, Contribution to the Mesochorinae (Hymenoptera, Ichneumonidae) of Nepal, Linzer biologische Beiträge 51 (2), pp. 1163-1174 : 1167-1168

Mesochorus weigeli nov.sp. ( figs 13-19 )

Holotype: (♀) Nepal, P: Mahakali, D: Darchula, Denli village, 2400 m, 27.VI.2017, LDD, leg. A. Weigel, # 17-15, 29°48´45´´N, 80°47´0´´E ( Erfurt )

Paratype:(♀) with same data (coll. Riedel ).

Description: ♀: Body length 3.5-3.7 mm. Flagellum with 29-31 flagellomeres; 1 st flagellomere length 7.5-7.8x width and 0.71x eye length; 2 nd flagellomere length 4.8- 5.0x width; preapical flagellomere c. 2x longer than wide. Temple strongly and roundly narrowed behind eye, dorsally c. 0.35x as long as eye. Distance of lateral ocellus to eye 1.0-1.1x ocellar diameter. Vertex and frons with fine scattered punctures. Face densely punctate, with weak central rim in dorsal half, 1.0x as wide as length of face+clypeus and 0.9x as wide as eye length; inner eye margins parallel. Subantennal transverse carina dipped medially. Ventral 1/3 of facial orbit and malar space with oblique striae. Clypeus with scattered punctures. Malar space 0.5x as long as width of mandibular base. Mandible with two equal teeth. Genal carina reaching hypostomal carina away from mandibular base, both carinae low.

Mesoscutum with superficial punctures, apico-medially with dense and longitudinal rugose-punctation. Mesopleuron with fine dense punctures dorsally and scattered setiferous punctures ventrally, speculum smooth. Metapleuron with finer dense punctures. Scutellum without lateral carina or apical tubercle, rounded in profile. Propodeum completely carinate. Area basalis shortly triangular, with long apical stalk. Area superomedia 1.6x longer than wide and 1.2x longer than area petiolaris; costula reaching area superomedia in its frontal 0.3. Area petiolaris 1.1-1.2x longer than wide, smooth. Hind femur 4.8-5.2x longer than wide; hind metatarsus 0.5x as long as hind tibia; hind claw with 3 basal and widely spaced teeth, 2 nd tooth longest.

Areolet quadrangular, shortly sessile; 2 nd recurrent vein in its middle. Nervulus interstitial. Pterostigma c. 3.6x longer than wide. Nervellus of hind wing slightly reclivous, not intercepted; discoidella absent.

1 st tergite 3.1x longer than wide. Postpetiolus with coarse striation, without lateral carina. 2 nd tergite 1.05x wider than long; thyridium transversely oval. Ovipositor sheath completely pilose, 6.8-7.5x longer than wide and 0.95-1.0x as long as hind metatarsus, moderately narrowed in apical 0.25.

Colour: Mainly reddish. Antenna reddish-brown. Head reddish; stemmaticum and occiput partly black; palps, mandible except teeth and malar space cream-yellow. Mesosoma reddish; two lateral stripes and one small anteromedial spot on mesoscutum, pronotum centrally, propleuron, mesopleuron and metapleuron blackish. Metasoma reddish; 1 st tergite brown to black, red basally; 2 nd tergite brown or black, ± reddish centrally, with narrow apical yellow band; following tergites reddish, ± brown laterally. Legs reddish; fore and mid coxae and all trochanters cream-yellow; hind coxa and hind femur with brownish-red suffusion; hind tibia cream-yellow, narrow base and subbasal ring weakly infuscate, apical 0.2 blackish (1.5x tibial width). Pterostigma brown, proximally and distally hyaline.

♂ unknown.

Remark: This species belongs to the declinans -group of Mesochorus (sensu SCHWENKE 1999). It is characterized by the stalked area basalis, partly rugose-punctate surface of mesoscutum, strongly striate postpetiolus, and pectination of hind claw. In the key of Nepalese Mesochorus ( KUSIGEMATI 1988), it runs to M. nepalensis KUSIGEMATI and M. interruptus KUSIGEMATI, but differs by many features, such as the surface structure of mesoscutum, striated postpetiolus, stalked area basalis and different colouration.

Figures

Figs 13-19: Mesochorus weigeli nov.sp. ♀: (13) habitus, (14) face, (15) propodeum, (16) ovipositor sheath, (17) mesopleuron, (18) postpetiolus, (19) head from dorsal.