Montichneumon Chen & Kikuchi, 2025

Genus Montichneumon Chen & Kikuchi gen. nov.

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Figs 2–5 View Fig View Fig View Fig View Fig

Type species

Montichneumon immortalibestia Chen & Kikuchi gen. et sp. nov., designated herein.

Diagnosis

This genus is identified as belonging to the Amblyteles genus-group (previous Amblytelina subtribe) based on the key of Tereshkin (2009) and can be separated from other Ichneumoninae tribes based on the following characters: face and clypeus divided by a groove ( Fig. 3B View Fig ); clypeus flat ( Fig. 3B, D View Fig ); propodeum with horizontal and declivous surfaces, the apex of the area dentipara distant from the base of the hind coxa ( Figs 2A View Fig , 3A View Fig ); propodeal spiracle linear ( Fig. 3A View Fig ); areolet pentagonal ( Fig. 4A View Fig ); female metasomal apex amblypygous ( Fig. 2 View Fig ); thyridium indistinct ( Figs 3G View Fig , 5D View Fig ); male abdominal sternum 9 usually medially convex on the apical margin ( Fig. 5E View Fig ).

Montichneumon gen. nov. can be diagnosed from other genera of the Amblyteles genus-group in having the following combination of characters: flagellum lacking white annulus or semi-annulus ( Fig. 2 View Fig ); malar space long in anterior view ( Fig. 3B View Fig ); mandible long and bidentate, evenly narrowed to apex with upper tooth longer than lower tooth ( Fig. 4B View Fig ); second segment of maxillary palps enlarged ( Fig. 3D View Fig ); scutellum weakly convex without lateral carina ( Fig. 3H View Fig ); propodeum at apex of area dentipara with small teeth, lacking strong teeth or apophysis ( Fig. 3A View Fig ); area basalis of propodeum lacking medial tubercle ( Figs 3F View Fig , 5C View Fig ); anterior transverse carina of propodeum present medially and absent laterally ( Figs 3F View Fig , 5C View Fig ); postpetiole of T1 flat and smooth with sparse punctures, lacking striae or rugae ( Figs 3A, G View Fig , 5D View Fig ); gastrocoelus long and narrow, shallowly impressed, thyridium indistinct ( Figs 3G View Fig , 5D View Fig ); T7 normal, not bending downwards laterally ( Fig. 2B View Fig ); metasomal sternites weakly sclerotized, with S2 and S3 unsclerotized with fold medially ( Fig. 4D View Fig ); male abdominal sternum 9 lacking medial process ( Fig. 5E View Fig ).

This genus is morphologically similar or closely related phylogenetically ( Fig. 1 View Fig ) to the following genera: Achaius , Achaiusoides , Amblyteles , Diphyus , Eutanyacra , Hepiopelmus , Limerodops, Serratichneumon , Spilichneumon , and Tricholabus . Montichneumon gen. nov. is morphologically most similar to Hepiopelmus in having a smooth postpetiole and narrowed gastrocoeli but differs in the weakly convex scutellum and completely sclerotized female S4 (scutellum highly elevated and female S4 unsclerotized in Hepiopelmus ); Limedrodops in having narrowed gastrocoeli and a similar metasoma shape but differs in the weakly convex scutellum and normal female T4–7 (scutellum highly elevated and lateral sides of female T4–T7 strongly bending downward ventrally in Limedrodops); Achaiusoides in having smooth and sparsely punctate postpetiole and enlarged second segment of maxillary palps but differs in the long area superomedia with lateral part of anterior transverse carina absent (area superomedia wide with lateral part of anterior transverse carina present in Achaiusoides ); it is also similar to some Oriental species of Diphyus (e.g., D. charlottae (Heinrich, 1965) , D. malaisei (Heinrich, 1965) , D. victoriae (Heinrich, 1965) , and D. uliae Sebalt, 2013 ) in having a yellow and black color pattern, weakly convex scutellum or narrowed gastrocoeli but differs in the smooth and sparsely punctate postpetiole and narrowed T1 (postpetiole striate and T1 wider in Diphyus ).

The differential diagnosis between Montichneumon gen. nov. and its morphologically similar genera (genera mentioned above except Amblyteles , Eutanyacra , and Spilichneumon ) is summarized in Table 2.

Etymology

The generic name ‘ Montichneumon ’ is derived from the Latin dative singular noun ‘ monti -’ (‘mountain’) plus ‘ ichneumon ’, reflecting that this new genus was collected from the high-elevation mountain of its type locality in Taiwan. The gender is masculine.

Description

HEAD ( Fig. 3B–D View Fig ). Mandible long and bidentate, evenly narrowed to apex with upper tooth longer than lower tooth; malar space longer than basal mandibular width; clypeus separated from face, flat and truncated in ventral margin; occipital carina strong and complete, meeting hypostomal carina above mandibular base; female flagellum bristle-shaped, slightly flattened medially and tapered apically; male flagellum with tyloids present on segments 9–19; flagellum lacking white annulus or semi-annulus.

MESOSOMA ( Fig. 3A, E–F View Fig ). Epomia present; notaulus indistinct; scutellum weakly convex without lateral carina, not strongly elevated above postscutellum; sternaulus indistinct; posterior transverse carina of mesosternum only present laterally; juxtacoxal carina present; propodeal carinae indistinct with anterior transverse carina only present medially, and longitudinal carinae weakly developed to posterior apex; area basalis without medial tubercle.

LEGS ( Fig. 2 View Fig ). Legs slender; female hind coxa without scopa; tarsal claws simple, without pecten.

WINGS ( Fig. 4A View Fig ). Fore wing with areolet pentagonal. Hind wing nervellus inclivous and intercepted below.

METASOMA ( Figs 3F–G View Fig , 4C–D View Fig , 5D–G View Fig ). Metasoma slender, parallel-sided and weakly tapering posteriorly; T1 flat in lateral view and smooth with sparse punctures; T2 polished, evenly (or sparsely) and minutely punctate; gastrocoelus indistinct, long and narrow, shallowly impressed; thyridium indistinct, transverse and narrower than interval between thyridia; female metasomal apex amblypygous; ovipositor not significantly projecting beyond metasomal apex; male abdominal sternum 9 convex on apical margin, without medial process; gonostyle simple.

Distribution

Taiwan.

Bionomics

See the Bionomics section of M. immortalibestia gen. et sp. nov. below.

Remarks

Sexual dimorphism in this genus is limited to body coloration (see Description of M. immortalibestia gen. et sp. nov. below).

Key to Palearctic and Oriental genera of the Amblyteles genus-group related to Montichneumon

Chen & Kikuchi gen. nov. (modified from Tereshkin (2011) and Sheng et al. (2023))

1. Propodeum with strong, upcurved apophysis at apex of area dentipara ............................................. .................................................................................................................. Amblyteles Wesmeal, 1845 View in CoL

– Propodeum toothless or with small or broad tooth at apex of area dentipara ................................... 2

2. Postpetiolus distinctly striate or longitudinally rugose ..................................................................... 3 – Postpetiolus not distinctly striated, smooth, sparsely punctate, or weakly rugose ........................... 7

3. Gastrocoeli distinct and deeply impressed, with interspace strongly arcuate; thyridia absent; anterior sternites of metasoma completely or strongly sclerotized; abdominal sternum 9 of male (hypopygium) without median process at apex ...................................................... Ctenichneumon Thomson, 1894

– Gastrocoeli variable from shallowly to deeply impressed, with interspace not arcuate; thyridia present, at least vestigial; anterior sternites of metasoma variable; abdominal sternum 9 of male with median process at apex ..................................................................................................................... 4

4. Mandibles of females normal or enlarged medially, with teeth blunt, flattened, or shortened; abdominal sternum 9 (hypopygium) of male with median process at apex long ............................. 5

– Mandibles of females normal, gradually narrowed apically with upper tooth longer than lower tooth; abdominal sternum 9 with median process at apex normal .............................................................. 6

5. S6 (hypopygium) of female with bunch of hard setae apically; propodeum in lateral profile with dorsal surface shorter than posterior surface; area superomedia wider than long or square ..................................................................................................... Eutanyacra Cameron, 1903

– S6 of female without bunch of hard setae apically; propodeum in lateral profile with dorsal surface longer than posterior surface; area superomedia always longer than wide ........................................ .......................................................................................................... Spilichneumon Thomson, 1894

6. Metasoma strongly elongate and narrowed posteriorly in female, but parallel-sided in male; scutellum highly elevated above postscutellum; T2–T3 longer than width; sides of T4–T7 strongly bending downward ventrally; T7 long, with dorsal profile convex in lateral view .......................................... ................................................................................................................. Limerodops Heinrich, 1949

– Metasoma wide, T3–T6 not elongate; scutellum slighly elevated above postscutellum; T7 normal ... .............................................................................................................. Diphyus Kriechbaumer, 1890

7. Gastrocoeli large and deep; S4 of female separated by median unsclerotized area with longitudinal fold (except Serratichneumon) ......................................................................................................... 8 – Gastrocoeli not distinctly deep; S4 of female completely sclerotized ............................................ 10

8. Propodeum of female without distinct carinae; scutellum slightly elevated above postscutellum; S4 sclerotized; flagellum of male without tyloids, strongly serrate ......................................................... ............................................................................................ Serratichneumon Riedel & Sheng, 2023 – Propodeum of female with distinct carinae; scutellum highly elevated above postscutellum; S4 largely unsclerotized; flagellum of male with or without tyloids, not serrate .................................. 9

9. Occipital carina joining hypostomal carina above base of mandible; thyridium narrower than interval between them; propodeum with tubercle in area basalis, area superomedia square or narrowed apically; flagellum of male with tyloids; abdominal sternum 9 of male without knoll-shaped swelling ................................................................................................ Hepiopelmus Wesmael, 1845

– Occipital carina joining hypostomal carina at base of mandible; thyridium wider than interval between them; propodeum with area basalis lacking tubercle, area superomedia hexagonal; flagellum of male without tyloids; abdominal sternum 9 of male with knoll-shaped swelling .......................... ............................................................................................................... Tricholabus Thomson, 1894

10. Second segment of maxillary palp not enlarged; T1 with postpetiole coriaceous or weakly rugose ... ...................................................................................................................... Achaius Cameron, 1903 – Second segment of maxillary palp enlarged; T1 with postpetiole smooth and sparsely punctate; T2 minutely or coarsely punctate between gastrocoeli .........................................................................11

11. Propodeum with area dentipara having carina transforming to broad tooth-like projection apically, area superomedia wider than long, with anterior transverse carina present laterally; mandibles short, with upper tooth longer than flattened, rounded lower tooth; T2 coarsely punctate between gastrocoeli ........................................................................................... Achaiusoides Tereshkin, 2011 – Propodeum with area dentipara having small tooth apically, area superomedia longer than wide, with anterior transvers carina absent laterally; mandibles long and evenly narrowed apically, with upper tooth longer than lower tooth; T2 minutely punctate between gastrocoeli ......................................... ....................................................................................... Montichneumon Chen & Kikuchi gen. nov.