Isadelphus nigrus Watanabe, 2021, sp. nov.
Creators: name: Watanabe, Kyohei
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Ichneumonidae
Isadelphus
Isadelphus nigrus

description: Isadelphus nigrus sp. nov.
(New SJN: Omagari-chibi-togari-himebachi)
(Figs 46A–E, 62I, 65P, 66P)
Etymology. The specific name is from the black (= Latin “ nigrus ”) body and legs.
Type series. Holotype: KPM-NK 82003, F, JAPAN, Kanagawa Pref., Yokohama City, Midori-ku, Niiharu, 28. III. 2007, M. Konishi leg. Paratypes: JAPAN, KPM-NK 81996, F, Hokkaido, Kuriyama Town, 8. VI. 2007, 22. VI. 2007, A. Ueda leg.; KPM-NK 81998, F, Fukushima Pref., Tajima Town, Tonyu, 8. VIII. 1999, 21. VIII. 1999, A. Shimizu leg.; KPM-NK 81991, 81992, 2 F, Saitama Pref., Yorii Town, 30. V. 2013, T. Nambu leg. (MsT); KPM-NK 81990, F, Kanagawa Pref., Hadano City, Mt. Koubou-yama, 5. IV. 2007, K. Watanabe leg.; KPM-NK 81995, F, Kanagawa Pref., Atsugi City, Funako, Tokyo University of Agriculture, 22. IV. – 16. V. 2016, Y. Kato & S. Koizumi leg. (MsT); KPM-NK 81999, F, Toyama Pref., Nanto City, Togamura, Kamimomose, 4–11. VIII. 2009, M. Watanabe et al. leg. (MsT); KPM-NK 81993, F, ditto, 15–29. IX. 2009; KPM-NK 82002, F, Toyama Pref., Nanto City, Togamura, Kamimomose, 21. VII. 2009, 28. VII. 2009, M. Watanabe et al. leg. (MsT); KPM-NK 82001, F, Hyogo Pref., Sayo Town, Funakoshi, 1. – 8. V. 2010; KPM-NK 81997, F, Kagoshima Pref., Yakushima Is., Hanyama, 1. V. – 5. VI. 2007, T. Yamauchi leg. (MsT); KPM-NK 82000, F, Kagoshima Pref., Yakushima Is., Kankake, 2. III. – 28. III. 2007, T. Yamauchi et al. leg. (MsT); KPM-NK 81994, F, ditto, 1. V. – VI. 2007.
Description. Female (n=14). Body length 4.3–7.3 (HT: 7.0) mm. Body polished, covered with silver setae.
Head. Clypeus 2.1 times as wide as maximum length, sparsely punctate, its anterior margin rounded, with a pair of weak teeth medially (Fig. 62I). Face matt, densely and finely punctate (Fig. 46B). MSL 0.9–1.0 (HT: 1.0) times as long as BWM. Frons matt, densely and finely punctate except for transverse striae on area above antennal socket. Gena and vertex densely punctate, inter space of punctures coriaceous. OOL slightly shorter than POL. OOL and POL longer than OD. Occipital carina complete, its lower end joined with hypostomal carina distant from mandibular base. Upper tooth of mandible slightly longer than lower tooth. Base of mandible slightly convex. Antenna with 22–24 (HT: 22) flagellomeres. FL III 3.3–4.0 (HT: 4.0) times as long as maximum depth in lateral view.
Mesosoma. Lateral part of pronotum densely punctate and coriaceous dorsally, longitudinally striate ventrally. Epomia short and weak. Mesoscutum matt, finely and densely punctate. Notaulus short and weak. Scutellum densely punctate, without a lateral longitudinal carina except for base. Mesopleuron punctate and longitudinally striate except for smooth speculum and smooth areas below speculum. Epicnemial carina strongly developed dorsally, reaching subtegular ridge. Posterior transverse carina of mesosternum largely absent in front of mid coxae. Metapleuron punctate, with a weak juxtacoxal carina. Propodeal carinae complete (Fig. 65P). Area basalis indistinct anteriorly (Fig. 65P). Area superomedia present, hexagonal (Fig. 65P). Anterior and median parts of propodeum irregularly rugulose and punctate. Posterior part of propodeum transversely rugulose. Length of fore wing 3.6–5.2 (HT: 5.2) mm. Areolet absent (Fig. 46D). Vein 2m-cu of fore wing with a single bulla (Fig. 46D). Nervellus inclivous, intercepted behind the middle (Fig. 46D). Hind femur 3.6–4.0 (HT: 4.0) times as long as maximum depth in lateral view. Hind TS I: II: III: IV: V = 2.0: 0.9–0.95 (HT: 0.95): 0.6: 0.3–0.4 (HT: 0.35): 0.45–0.5 (HT: 0.5). Tarsal claws simple.
Metasoma. T I 1.6–1.8 (HT: 1.7) times as long as maximum width, coriaceous except for smooth posterior margin, posterior part usually with some short and weak longitudinal striae. Median dorsal carina of T I present basally, weak. Dorsolateral carina of T I complete. T II to T VI wider than long. T II granulate (Fig. 46E). T III granulate anteriorly, sparsely and finely punctate posteriorly. T IV to T VII sparsely and finely punctate. Ovipositor sheath 1.3–1.35 (HT: 1.3) times as long as hind tibia. Ovipositor decurved (Fig. 46A), with an indistinct nodus and ventral teeth (Fig. 66P).
Coloration (Figs 46A–E). Body (excluding wings and legs) black to blackish brown. Palpi dark brown. Posterior margins of T II to T IV narrowly tinged with reddish brown. Posterior margins of T V to T VII with a conspicuous white band. Membranous part of metasomal sternites yellowish brown. Ovipositor reddish brown. Wings hyaline. Veins and pterostigma dark brown to blackish brown. Legs blackish brown to black except for apex and base of each segment more or less narrowly tinged with reddish brown to yellowish brown.
Male. Unknown.
Distribution. Japan (Hokkaido and Honshu).
Bionomics. Host unknown. KPM-NK 81991 and 81992 collected in the malaise trap in Bamboo forest.
Remarks. This species resembles I. compressus in the body structures and coloration but can be distinguished by the above key.
description: Published as part of Watanabe, Kyohei, 2021, Taxonomic and Zoogeographic Study of the Japanese Phygadeuontinae (Hymenoptera, Ichneumonidae), with Descriptions of 17 New Species, pp. 55-136 in Bulletin of the Kanagawa Prefectural Museum (Natural Science) 50 on pages 108-110, DOI: 10.32225/bkpmnh.2021.50_55, http://zenodo.org/record/12774639