Homotropus formosus Klopfstein, 2014

Morishita, Shunsuke & Watanabe, Kyohei, 2025, Review of the genera Homotropus Förster and Syrphoctonus Förster (Hymenoptera, Ichneumonidae, Diplazontinae) from Japan, Zootaxa 5588 (1), pp. 49-76 : 56-59

Homotropus formosus Klopfstein, 2014

( Figs 5 A–C )

Homotropus formosus Klopfstein, 2014: 23 .

Specimens examined. JAPAN: [Hokkaido] 1F, Kamikawa Town, Ginsendaisen , 1. VIII. 2021, K. Watanabe leg. (KPMNH); 1F, Chitose City, Bifue, Kusabue-rindo , 8–21 VII 2012, N. Kuhara leg. (MsT) ( EUM). [Honshu] 1F, Gunma Pref., Tsumagoi Vil., Kanbara, Takamine-kogen , 3. IX. 2015, K. Watanabe leg. ( KPMNH); 1F, ditto , 23. VIII . 2016 , S. Shimizu leg. (KPMNH); 1F, Kanagawa Pref., Mt. Hinokiboramaru , 23. VI . 2013 , (FIT) (KPMNH); 1F, Kanagawa Pref., Odawara City, Kamisoga , 29. IV. 2017, K. Watanabe leg. ( KPMNH); 1F, Toyama Pref., Toyama City, Arimine, Inonedani , 25 VIII –1 IX 2009 , M. Watanabe leg. (MsT) (KPMNH); 1F, ditto, 15–22 IX 2009, M. Watanabe leg. (MsT) ( KPMNH); 4F, Nagano Pref., Otaki Vil., Mt. Ontakesan, Hakkaisan , 7. VIII . 2010 , K. Watanabe leg. (KPMNH); 2F, ditto, 4. VIII . 2017 , K. Watanabe leg. (KPMNH); 2F, Nagano Pref., Otaki Vil., Mt. Ontakesan , 25 VI –15 VII 2015 , S. Shimizu leg. (MsT) (KPMNH); 1F, Aichi Pref., Shitara Town, Tsuguhonsawa , 26 V–23 VI 2020 , S. Morishita leg. (MsT) (TMNH). [Kyushu] 1F, Kagoshima Pref., Takachihonomine , 27. VII. 1973, K. Kusigemati leg. ( SEHU) .

Diagnosis. Antenna with 21–22 (in female) or 23 (in male) flagellomeres. Tyloids on FL VII to FL XV in male. Face coriaceous and matt; densely punctate. Clypeus depressed apically; robes rounded at outer corners. Mesoscutum coriaceous and matt in female; coriaceous and polished in male; densely punctate in both sexes. Mesopleuron coriaceous and matt; densely punctate except for small smooth area around the speculum ( Fig. 5 C ). Propodeum finely rugulose; posterior part of lateromedian longitudinal carina and pleural carina present. Fore wing length 5.0–7.0 mm. Areolet present. Dorsal part of hind coxa coriaceous and matt. Metasoma dorsoventrally depressed in both sexes. Latero-median carina usually indistinct; at most present on basal 0.4 of T I ( Fig. 1 A ). T I 1.1–1.3 × as long as maximum width; rugulose laterally, otherwise coriaceous. T II 0.8–0.9 × as long as maximum width. Face without pair of yellow markings along each inner orbits ( Fig. 5 B ). Face black with yellow median marking which separated from clypeus in female ( Fig. 5 B ); entirely yellow in male. Clypeus entirely yellow to brown in both sexes ( Fig. 5 B ). Malar space entirely black in female ( Fig. 5 B ); entirely yellow in male. Yellow shoulder markings of mesoscutum present ( Fig. 5 A ). Scutellum entirely black. All coxae entirely black in female ( Fig. 5 A ). Fore and mid coxae entirely yellow; hind coxa black with yellow apices in male. Hind tibia white; darkened basally and apically; often with a black subbasal marking. Metasoma entirely black in female. T III sometimes with pair of yellow to brown basal marking in male. T IV sometimes each with transverse yellow basal band in male.

Distribution. Japan (Hokkaido, Honshu, and Kyushu). Outside Japan, this species is distributed in Russia ( Yu et al. 2016).

Bionomics. Host is unknown. In Japan, adults were collected in broad-leaved forest.

Remarks. This is the first record of this species from Honshu and Kyushu. Japanese specimens share the character states defined in the original description ( Klopfstein 2014a), while female Japanese specimens collected in Honshu differ from the original description in the following character states: clypeus yellowish-brown to brown ( Fig. 5 B ) (entirely yellow in the original description); fore and mid femora, tibiae, and tarsomeres brown to blackish-brown ( Fig. 5 A ) (entirely orange in the original description); hind femur entirely black ( Fig. 5 A ) (entirely orange in the original description); fore wing length 5.0–7.0 mm (5.1–5.5 mm in the original description). However, as no significant differences were found in other character states, we conclude that the observed variation is intraspecific variation within a single species.

Figures

FIGURE 1. Japanese Homotropus spp., females—A, B: T I, dorsal view; C: propodeum, dorsal view.A: H.formosus Klopfstein, 2014; B: H. sundevalli (Holmgren, 1858); C: H. klopfsteinae Johansson, 2020.

FIGURE 5. Homotropus formosus Klopfstein, 2014, female―A: lateral habitus; B: head, frontal view; C: mesopleuron, lateral view.