Isadelphus Förster, 1869

Watanabe, Kyohei, 2021, Taxonomic and Zoogeographic Study of the Japanese Phygadeuontinae (Hymenoptera, Ichneumonidae), with Descriptions of 17 New Species, Bulletin of the Kanagawa Prefectural Museum (Natural Science) 50, pp. 55-136 : 108

Genus Isadelphus Förster, 1869

Isadelphus Förster, 1869: 177 . Type: Hemiteles inimicus Gravenhorst, 1829 . Designated by Viereck (1914).

Perosis Förster, 1869: 169 . Type: Echthrus armatus Gravenhorst, 1829 . Designated by Viereck (1914).

Cecidonomus Bridgman, 1880: 264 . Type: Cecidonomus gallicola Bridgman, 1880 .Designated by Viereck (1914). In this study, I record a new species, I. nigrus sp. nov., from Japan. This is the first record of this genus from Japan. Key to Eastern Palearctic species can be distinguished by the following key.

Key to Eastern Palearctic species of the genus Isadelphus (♀)

1. Hind coxa red to reddish yellow. Anterior part of clypeus with a tongue-like protrusion, its apex more or less truncate. Metasomal tergites at least partly red. .......................................... I. inimicus ( Gravenhorst, 1829)

-. Hind coxa brown to black ( Fig. 46A ). Anterior part of clypeus with two weak or indistinct teeth ( Fig. 62I ). Metasomal tergites at most tinged with brown. ............................................................................................ 2

2. Hind coxa and T II brown. Ovipositor sheath 1.8 times as long as hind tibia. .................................................. I. compressus Sheng, 2001

-. Hind coxa and T II black ( Figs 46A, C, E ). Ovipositor sheath 1.35 times as long as hind tibia. ................................................................... I. nigrus sp. nov.

Figures

Fig. 46. Isadelphus nigrus sp. nov., KPM-NK 82002 (A, B, paratype) and 82003 (C-E, holotype), females ― A, lateral habitus; B, head, frontal view; C, head, mesosoma, and metasoma, dorsal view; D, wings; E, T I to T III, dorso-lateral view.

Fig. 62. Bathythrix kuwanae Viereck, 1912 (A, KPM-NK 81718), Ba. margaretae Sawoniewicz, 1980 (B, KPM-NK 55017), Ba. thomsoni (Kerrich, 1942) (C, KPM-NK 81675), Diaglyptidea conformis (Gmelin, 1790) (D, KPM-NK 81645), Nipponaetes haeussleri (Uchida, 1933) (E, KPM-NK 81832), Acrolyta japonica sp. nov. (F, N, KPM-NK 54996, holotype), Acr. rufocincta (Gravenhorst, 1829) (G, KPM-NK 81732), Surculus japonicus sp. nov. (H, KPM-NK 81861, holotype), Isadelphus nigrus sp. nov. (I, KPM-NK 82003, holotype), Lochetica japonica sp. nov. (J, KPM-NK 81989, holotype), Megacara similis Sheng, 1999 (K, KPM-NK 81837), Gnotus chionops (Gravenhorst, 1829) (L, KPM-NK 82100), Gn. striatus (Uchida, 1930) (M, KPM-NK 82060), and Acr. flavicoxis Sheng & Sun, 2014 (O, KPM-NK 81837), females from Japan ― A–C, head, frontal view; D, E, head, lateral view; F–K, anterior margin of clypeus; L, M, mandible; N, O, basal part of antenna, lateral view.