Coelichneumon opulentus (Taschenberg, 1871)

Riedel, Matthias & Watanabe, Kyohei, 2021, The genus Coelichneumon Thomson in Japan (Hymenoptera, Ichneumonidae, Ichneumoninae), Zootaxa 4948 (4), pp. 501-545 : 533-534

Coelichneumon opulentus var.?

Materials examined: JAPAN: 1 ♂, Tochigi Pref., Nasushiobara City, Shiobara, Utou-sawa , 700 m alt., 22– 28.v.2008, T. Matsumura leg., MT ; 1 ♂, Niigata Pref., Sado Is., Kanaishinbo, Hakundai to Mt. Myouken-zan , 38.520°N 138.2015°E, 830–1000 m alt., 10.xi.2010, K. Watanabe leg.

Description: ♂: Body length 13‒14 mm. Flagellum with 37 flagellomeres; 1 st flagellomere 2.8× longer than wide. Tyloids on flagellomeres 9‒16, linear, maximally 0.4× as long as their flagellomere. Temple strongly and almost linearly narrowed behind eye. OED 1.0× and OOD 1.2× ocellar diameter. Frons with fine transverse rugae. Face densely punctate and granulate. Clypeus smooth, with dense punctures. Gena 0.7× as wide as eye, with rather dense punctures. MI 0.2.

Mesosoma with pale hairs. Notaulus impressed in frontal 1/3 of mesoscutum. Mesoscutum with rather dense punctures and fine granulation but shining. Mesopleuron and metapleuron with rather dense punctures; juxtacoxal carina present. Scutellum slightly elevated, slightly longer than wide, with scattered punctures and with lateral carina in basal 0.2. Area basalis slightly bulged forward medially. Area superomedia sickle-shaped, c.2× wider than long, fine rugose. Area externa with fine granulation. Fore metatarsus with blunt apical tooth. Hind femur 4.0× longer than wide.

Areolet almost quadrangular, frontal distance between veins 2rs-m and 3rs-m 1× their width; vein 2m-cu in its middle. Vein 1cu-a postfurcal by 1× its width.

Lateral field of postpetiolus 0.7× as wide as median field, punctate; median field coarsely aciculate. 2 nd tergite 1.05× longer than wide. Gastrocoelus strongly impressed. Thyridium almost transverse, 1.5× wider than the interval. 2 nd to 4 th tergites densely punctate; 2 nd and 3 rd tergites with strong medial aciculation.

Color: Black, metasoma with distinct bluish shine. Palps, mandible except teeth, labrum, clypeus, face, wide frontal orbit, triangular spot on vertex, gena and outer orbit, scape ventrally, collare, propleuron, upper margin and ventral edge of pronotum, tegula, subtegular ridge, two longitudinal stripes on mesoscutum, two roundish spots on mesopleuron, caudal spot on mesosternum, scutellum and postscutellum, large spot on metapleuron, roundish spot on area petiolaris and posterolateral spots or apical band on postpetiolus ivory. Legs black; fore and mid coxae and trochanters ivory; hind coxa with dorsal and ventral ivory spots; central ring of hind femur, subbasal rings of all tibiae and fore and mid legs frontally ivory. Wings hyaline; pterostigma black.

Remarks: The males are much smaller than typical males of C. opulentus and differ by entirely black flagella and black hind tarsi, but have a typical structure and color pattern otherwise. They might represent a small variant of C. opulentus rather than a separate species.

Distribution: Japan (Honshu and Sado Is.).