Homotropus Förster, 1869

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 : 51-52

publication ID	https://doi.org/10.11646/zootaxa.5588.1.2
publication LSID	lsid:zoobank.org:pub:D6A24D15-616C-4BEB-B7F9-132180AE0C12
persistent identifier	https://treatment.plazi.org/id/03D487FD-FF9A-8B6E-1BBA-20CD1BC4FF17
treatment provided by	Plazi (2025-02-19 22:05:08, last updated by Guilherme 2025-02-25 16:28:27)
scientific name	Homotropus Förster, 1869
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Treatment

Genus Homotropus Förster, 1869 View in CoL

Homotropus Förster, 1869: 162 View in CoL . Type species: Bassus elegans Gravenhorst, 1829 . Designated by Viereck (1912).

Homoporus Thomson, 1890: 1488 View in CoL . Lapsus for Homotropus View in CoL .

Homocidus Morley, 1911: 87 . New name for Homoporus View in CoL .

Diagnosis. According to Klopfstein (2014b), this genus can be distinguished from other genera by the following combination of character states. Face coriaceous and matt; without vertical impressions; entirely black or black with yellow central marking in female ( Figs 2 B View FIGURE 2 , 3 B View FIGURE 3 , 4 B View FIGURE 4 , 5 B View FIGURE 5 , 6 B View FIGURE 6 , 7 B View FIGURE 7 , 9 B View FIGURE 9 , 10 B View FIGURE 10 , 11 B View FIGURE 11 , 12 B View FIGURE 12 , 13 B View FIGURE 13 ); entirely yellow or black with yellow inner orbits and yellow central marking in male ( Figs 2 E View FIGURE 2 , 3 E View FIGURE 3 , 4 D View FIGURE 4 , 6 F View FIGURE 6 , 8 B View FIGURE 8 , 10 E View FIGURE 10 , 11 F View FIGURE 11 , 12 F View FIGURE 12 , 13 D View FIGURE 13 ). Clypeus usually with thin apical margin; impressed along apical margin; resulting in central area being convex. Antenna with apical flagellomeres usually longer than wide. Tyloids always present in male; linear and narrow and without long setae in most species (exceptions: H. tauriscorium and H. venustus ). Mesoscutum without notaulus; variously sculptured, ranging from entirely smooth and shining, with or without punctures, to being strongly coriaceous and matt; yellow shoulder markings present or absent; inner corners of markings (if present) sometimes extended into two parallel lines on mesoscutum. Scutellum only carinate basally. Mesopleuron sometimes entirely smooth and shining; often punctate and/or coriaceous at least on lower half; epicnemial carina complete ventrally. Propodeum sometimes with full set of carinae enclosing basal, petiolar, and lateral areas; carinae usually partly or fully reduced; spiracle inconspicuous. Areolet present or absent, if present, vein 3rs-m often interrupted or unpigmented. Hind wing with 2–4 basal hamuli. Hind tibia with various colouration, i.e., orange, yellow, or white with dark apex and subbasal spot, very rarely ( H. venustus ) even black-white-black banded. Female metasoma usually evenly tapered to apex ( Figs 3 D View FIGURE 3 , 6 D View FIGURE 6 ); sometimes strongly compressed posterior to third segment ( Fig. 12 D View FIGURE 12 ); posterior margins never concave; without transverse impressions. T I usually without latero-median carina, but if carina present, its two carinae converge over basal half, parallel, and widely separated on apical half ( Fig. 1 B View FIGURE 1 ). T II with spiracle above lateral fold. T III with spiracle usually above (but rarely below) or behind lateral fold. Metasoma black ( Fig. 3 D View FIGURE 3 ); sometimes with yellow markings, or marked with orange ( Figs 6 D, G View FIGURE 6 , 11 G View FIGURE 11 , 12 D View FIGURE 12 ). Ovipositor sheaths 0.3 × as long as hind tibia; either parallel-sided and fully enclosing ovipositor or tapered and diagonally truncate; with inconspicuous setae ventrally and apically. T VIII and T IX of male present as separate sclerites; hypopygium about 2.0 × wider than long, emarginated apically and forming two lobes; outer corners of lobes rounded.

Distribution. Holarctic, Neotropical, and Oriental regions ( Yu et al., 2016).

Key to the Japanese species of the genus Homotropus

(males of H. kuroashii and H. japonicum are unknown)

1. Face black with pair of yellow markings along each inner orbit ( Fig. 8 B View FIGURE 8 ). Propodeum with petiolar area surrounded by carinae ( Fig. 1 C View FIGURE 1 ).......................................................... Homotropus klopfsteinae Johansson, 2020

-. Face without pair of yellow markings along each inner orbit ( Figs 2 B, E View FIGURE 2 , 3 B, E View FIGURE 3 , 4 B, D View FIGURE 4 , 5 B View FIGURE 5 , 6 B, F View FIGURE 6 , 7 B View FIGURE 7 , 9 B View FIGURE 9 , 10 B, E View FIGURE 10 , 11 B, F View FIGURE 11 , 12 B, F View FIGURE 12 , 13 B, D View FIGURE 13 ). Character states of propodeum various.................................................... 2

3. Female............................................................................................. 3

-. Male.............................................................................................. 14

3. Fore and mid coxae mainly yellow to orange ( Figs 2 A View FIGURE 2 , 10 A View FIGURE 10 ). Metasoma entirely black (e.g., Fig. 3 D View FIGURE 3 )................. 4

-. Coloration of fore and mid coxae mainly black, at most with yellow apices ( Figs 3 A View FIGURE 3 , 4 A View FIGURE 4 , 5 A View FIGURE 5 , 6 A View FIGURE 6 , 7 A View FIGURE 7 , 9 A View FIGURE 9 , 13 A View FIGURE 13 ). If fore and mid coxae mainly yellow to orange, T II to T IV with orange markings (e.g., Fig. 12 D View FIGURE 12 )............................. 5

4. Face entirely black or black with small median marking ( Fig. 2 B View FIGURE 2 ). Scutellum black with yellow apical marking ( Fig. 2 C View FIGURE 2 )......................................................................... Homotropus areolaris ( Uchida, 1957)

-. Face with yellow marking confluent with yellow clypeus ( Fig. 10 B View FIGURE 10 ). Scutellum yellow with black basomedian marking which sometimes reduced ( Fig. 10 C View FIGURE 10 )............................................. Homotropus megaspis Thomson, 1890

5. Scutellum entirely black (e.g., Fig. 12 C View FIGURE 12 )................................................................... 6

-. Scutellum black with yellow marking (e.g., Figs 2C View FIGURE 2 , 10 C View FIGURE 10 , 11 C View FIGURE 11 )............................................... 10

6. Metasoma compressed apically ( Fig. 12 D View FIGURE 12 ). T II to T IV entirely orange ( Fig. 12 D View FIGURE 12 )................................................................................................... Homotropus signatus ( Gravenhorst, 1829)

-. Metasoma dorsoventrally depressed (e.g., Figs 3 D View FIGURE 3 , 6 D View FIGURE 6 ). Coloration of T II to T IV various.......................... 7

7. T II to T IV with brown markings ( Fig. 6 D View FIGURE 6 ). Punctures of mesopleuron usually absent, at most very sparsely punctate anteriorly and ventrally ( Fig. 6 C View FIGURE 6 ).................................................. Homotropus infuscatus ( Uchida, 1957)

-. Metasoma entirely black (e.g., Fig 3 D View FIGURE 3 ). Mesopleuron densely punctate ( Figs 3 C View FIGURE 3 , 5 C View FIGURE 5 , 9 C View FIGURE 9 ).......................... 8

8. Yellow shoulder markings of mesoscutum absent ( Fig. 3 A View FIGURE 3 ). Areolet usually absent ( Fig. 3 A View FIGURE 3 ). Latero-median carina present basal 0.7–0.9 of T I (e.g., Fig. 1 B View FIGURE 1 ). T II less than 0.65 × as long as maximum width.................................................................................................... Homotropus crassicornis Thomson, 1890

-. Yellow shoulder markings of mesoscutum present ( Figs 5 A View FIGURE 5 , 9 A View FIGURE 9 ). Areolet present (e.g., Fig. 13 C View FIGURE 13 ). Latero-median carina usually indistinct, at most present on less than basal 0.4 of T I (e.g., Fig. 1 A View FIGURE 1 ). T II more than 0.8 × as long as maximum width ................................................................................................... 9

9. Mesopleuron coriaceous and matt over entire surface; densely punctate except for small smooth area around speculum ( Fig. 5 C View FIGURE 5 ). Mesoscutum coriaceous and matt between punctures....................... Homotropus formosus Klopfstein, 2014

-. Mesopleuron smooth and polished except for coriaceous area on lower half of mesopleuron; densely punctate except for on and below speculum ( Fig. 9 C View FIGURE 9 ). Mesoscutum weakly coriaceous and polished between punctures........................................................................................... Homotropus kuroashii ( Uchida, 1957) (part)

10. Latero-median carina present basal 0.7–0.9 of T I ( Fig. 1 B View FIGURE 1 ). Propodeum coarsely rugulose ( Fig. 13 E View FIGURE 13 )..................................................................................... Homotropus sundevalli ( Holmgren, 1858)

-. Latero-median carina usually indistinct, at most present on less than basal 0.4 of T I (e.g., Fig. 1 A View FIGURE 1 ). Propodeum at most finely rugulose (e.g., Fig. 11 D View FIGURE 11 ).............................................................................. 11

11. T II to T IV entirely or largely orange (e.g., Fig. 12 D View FIGURE 12 )....................................................... 12

-. T II to T IV entirely black (e.g., Fig. 3 D View FIGURE 3 )................................................................. 13

12. Mesopleuron densely punctate except for on and below speculum (e.g., Fig. 9 C View FIGURE 9 ). Scutellum black with yellow apical marking (e.g., Fig. 2 C View FIGURE 2 ). Propodeum sometimes with some rugae centrally............... Homotropus elegans ( Gravenhorst, 1829)

-. Punctures on mesopleuron usually absent; at most with very sparse punctures anteriorly and ventrally (e.g., Fig. 6 C View FIGURE 6 ). Scutellum black with largely yellow marking ( Fig. 11 C View FIGURE 11 ). Propodeum without rugae......... Homotropus pallipes ( Gravenhorst, 1829)

13. Hind tibia black with subbasal white marking ( Fig. 7 C View FIGURE 7 ). Fore wing length 6.5–8.5 mm. T I 0.9–1.1 × as long as maximum width. T II 0.6–0.7 × as long as maximum width. T II 0.9–0.95 × as long as T I........... Homotropus japonicum sp. nov.

-. Hind tibia white; darkened basally and apically ( Fig. 9 D View FIGURE 9 ). Fore wing length 4.5–6.0 mm. T I 1.05–1.25 × as long as maximum width. T II 0.85–1.1 × as long as maximum width. T II 1.0–1.05 × as long as T I...... Homotropus kuroashii ( Uchida, 1957)

14. T III entirely or largely orange (e.g., Fig. 9 D View FIGURE 9 ).............................................................. 15

-. T III entirely or largely black (e.g., Figs 6 G View FIGURE 6 , 11 G View FIGURE 11 ).......................................................... 16

15. Malar space entirely yellow ( Fig. 4 D View FIGURE 4 ). Scutellum black with yellow apical marking (e.g., Fig. 2 C View FIGURE 2 ). Mesopleuron densely punctate except for on and below speculum (e.g., Fig. 9 C View FIGURE 9 ).................... Homotropus elegans ( Gravenhorst, 1829)

-. Malar space entirely black ( Fig. 12 F View FIGURE 12 ). Scutellum entirely black (e.g., Fig. 12 C View FIGURE 12 ). Punctures on mesopleuron usually absent, at most with very sparse punctures anteriorly and ventrally (e.g., Fig. 6 C View FIGURE 6 )......... Homotropus signatus ( Gravenhorst, 1829)

16. Scutellum entirely black (e.g., Fig. 12 C View FIGURE 12 ).................................................................. 17

-. Scutellum black with yellow marking (e.g. Figs 2C View FIGURE 2 , 10 C View FIGURE 10 , 11 C View FIGURE 11 )............................................... 19

17. Clypeus bicolour (yellow with basal brown marking) ( Fig. 6 F View FIGURE 6 ). Metasoma black with yellow to brown marking ( Fig. 6 G View FIGURE 6 )....................................................................... Homotropus infuscatus ( Uchida, 1957)

-. Clypeus unicolour (entirely yellow) ( Fig. 2 E View FIGURE 2 , 3 F View FIGURE 3 , 10 E View FIGURE 10 , 11F View FIGURE 11 ) Metasoma entirely black (e.g., Fig. 3 D View FIGURE 3 )................. 18

18. Areolet absent ( Fig. 3 A View FIGURE 3 ). Latero-median carina present basal 0.7–0.9 of T I (e.g., Fig. 1 B View FIGURE 1 ). Antenna with 20 flagellomeres..................................................................... Homotropus crassicornis Thomson, 1890

-. Areolet present (e.g., Fig. 13 C View FIGURE 13 ). Latero-median carina of T I usually indistinct, at most present on less than basal 0.4 of T I ( Fig. 1 A View FIGURE 1 ). Antenna with 23 flagellomeres....................................... Homotropus formosus Klopfstein, 2014

19. Latero-median carina present basal 0.7–0.9 of T I ( Fig. 1 B View FIGURE 1 ). Hind coxa entirely black ( Fig. 13 C View FIGURE 13 ). Propodeum coarsely rugulose ( Fig. 13 E View FIGURE 13 )........................................................... Homotropus sundevalli ( Holmgren, 1858)

-. Latero-median carina of T I usually indistinct, at most present on less than basal 0.4 of T I (e.g., Fig. 1 A View FIGURE 1 ). Hind coxa black or orange with yellow apex ( Figs 2 D View FIGURE 2 , 10 D View FIGURE 10 , 11 E View FIGURE 11 ). Propodeum at most finely rugulose (e.g., Fig 11 D View FIGURE 11 ).................. 20

20. T II to T IV with irregular orange markings ( Fig. 11 G View FIGURE 11 ). Mesopleuron punctures usually absent, at most with very sparse punctures anteriorly and ventrally (e.g., Fig. 6 C View FIGURE 6 )............................ Homotropus pallipes ( Gravenhorst, 1829)

-. T II to T IV entirely black (e.g., Fig. 3 D View FIGURE 3 ). Mesopleuron densely punctate except for on and below speculum (e.g., Fig. 9 C View FIGURE 9 ).. .................................................................................................. 21

21. Scutellum black with yellow apical marking (e.g., Fig. 2 C View FIGURE 2 )....................... Homotropus areolaris ( Uchida, 1957)

-. Scutellum yellow with black basomedian marking which sometimes reduced (e.g., Fig. 10 C View FIGURE 10 )............................................................................................... Homotropus megaspis Thomson, 1890

References

Forster, A. (1869) Synopsis der Familien und Gattungen der Ichneumonen. Verhandlungen des Naturhistorischen Vereins der Preussischen Rheinlande und Westfalens, 25 (1868), 135-221.

Gravenhorst, J. L. C. (1829) Ichneumonologia Europaea. Pars III. Sumtibus auctoris, Vratislaviae, 1097 pp. https://doi.org/10.5962/bhl.title.65750

Holmgren, A. E. (1858) Forsok till uppstallning och beskrifning af de isverige funna Tryphonider (Monographia Tryphonidum Sueciae). Kongliga Svenska Ventenskapsakademiens Handlingar Neue Folge, 1 (2), 305-394.

Johansson, N. (2020) Additions to the Swedish fauna of Diplazontinae (Hymenoptera: Ichneumonidae) with the descriptions of five new species. European Journal of Taxonomy, 724, 70-92. https://doi.org/10.5852/ejt.2020.724.1159

Klopfstein, S. (2014 b) Revision of the Western Palaearctic Diplazontinae (Hymenoptera, Ichneumonidae). Zootaxa, 3801 (1), 5-125. https://doi.org/10.11646/zootaxa.3801.1.1

Morley, C. (1911) Ichneumonologia Britannica. IV. The Ichneumons of Great Britain. Tryphoninae. H. & W. Brown, London, 344 pp.

Thomson, C. G. (1890) XLIII. Ofversigt af arterna inom slagtet Bassus (Fab.). Opuscula Entomologica, Lund, XIV, 1459-1525.

Uchida, T. (1957) Beitraege zur kenntnis der Diplazoninen fauna japans und seiner umgegenden (Hymenoptera, Ichneumonodae). Journal of Faculty Agricultural Hokkaido University, Sapporo, 50, 226-265.

Viereck, H. L. (1912) Tryphoninae - A review. Proceedings of the Entomological Society of Washington, 14, 175-178.

Yu, D. S., van Achterberg, C. & Horstmann, K. (2016) Taxapad 2016. Ichneumonoidea 2015. Database on flash-drive. Available from: http://www.taxapad.com (accessed 26 August 2024)

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 2. Homotropus areolaris (Uchida, 1957), female (A–C) and male (D, E)―A, D: lateral habitus; B, E: head, frontal view; C: scutellum, dorsal view.

FIGURE 3. Homotropus crassicornis Thomson, 1890, female (A–D) and male (E, F)―A, E: lateral habitus; B, F: head, frontal view; C: mesopleuron, lateral view; D: metasoma, dorsal view.

FIGURE 4. Homotropus elegans (Gravenhorst, 1829), female (A, B) and male (C, D)―A, C: lateral habitus; B, D: head, frontal view.

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

FIGURE 6. Homotropus infuscatus (Uchida, 1957), female (A–D) and male (E–G)―A, E: lateral habitus; B, F: head, frontal view; C: mesopleuron, lateral view; D, G: T II to apex of metasoma, dorsal view.

FIGURE 7. Homotropus japonicum sp. nov., female―A: lateral habitus; B: head, frontal view; C: hind tibia, lateral view.

FIGURE 8. Homotropus klopfsteinae Johansson, 2020, male―A: lateral habitus; B: head, frontal view.

FIGURE 9. Homotropus kuroashii (Uchida, 1957), female―A: lateral habitus; B: head, frontal view; C: mesopleuron, lateral view; D: hind tibia, lateral view.

FIGURE 10. Homotropus megaspis Thomson, 1890, female (A–C) and male (D, E)―A, D: lateral habitus; B, E: head, frontal view; C: scutellum, dorsal view.

FIGURE 11. Homotropus pallipes (Gravenhorst, 1829), female (A–D) and male (E–G)―A, E: lateral habitus; B, F: head, frontal view; C: scutellum, dorsal view; D: propodeum, dorsal view; G: T II to T IV, dorsal view.

FIGURE 12. Homotropus signatus (Gravenhorst, 1829), female (A–D) and male (E, F)―A, E: lateral habitus; B, F: head, frontal view; C: scutellum, dorsal view; D: T II to apex of metasoma, dorsal view.

FIGURE 13. Homotropus sundevalli (Holmgren, 1858), female (A, B) and male (C–E)―A, C: lateral habitus; B, D: head, frontal view; E: propodeum, dorsal view.