Serratichneumon Riedel & Sheng, 2023

Sheng, Mao-Ling, Riedel, Matthias & Wang, Zhong, 2023, A new genus and species of Ichneumonini Latreille (Hymenoptera, Ichneumonidae, Ichneumoninae) from Oriental Region, European Journal of Taxonomy 910, pp. 14-24 : 15-16

Serratichneumon Riedel & Sheng gen. nov.

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Type species

Serratichneumon maculatus Sheng & Riedel gen. et sp. nov.

Etymology

The name of the new genus is based on the male’s serrated flagellomeres. The gender is masculine.

Diagnosis

Flagellum of female slightly lanceolate, of male strongly serrate ( Fig. 14 ). Clypeus flat, with slightly widened and leaf-like lateral parts, apical margin almost straight. Mandible ( Fig. 3 ) with two rather distinctly separated teeth, lower tooth smaller than upper tooth and slightly bent inwards. Genal carina reaching hypostomal carina close to the base of mandible. Gena ( Figs 4–5 ) not or slightly narrowed behind the eye. Occiput strongly concave medially. Notaulus short, pit-like impressed on frontal margin of mesoscutum. Mesoscutum densely punctate. Scutellum slightly to moderately convex and wider than long, not carinate laterally. Mesopleuron rugose-punctate; sternaulus not impressed. Epicnemial carina low, dorsally reaching center of mesopleuron at or close to its frontal margin. Juxtacoxal carina absent. Propodeum rounded in profile but slightly differentiated in a shorter basal ± horizontal and longer apical vertical part, coarsely rugose-punctate, without apophysis; propodeal spiracle oval or slit-shaped; carination of propodeum largely obsolete, at least in females. Area basalis with a small median tubercle. Area superomedia absent or incomplete; anterior transverse carina (costula) absent or weak. Hind coxa without scopa. Claws simple. Metasoma strongly amblypygous. Gastrocoelus distinctly impressed, with some fine longitudinal ridges. Thyridium oblique, ca 0.7 × as wide as the interval between thyridia. 2 nd to 4 th sternites with median membranous folds. Ovipositor sheath short, not surpassing metasomal apex. Hypopygium of female very similar to male, not modified, apical margin wide, slightly rounded.

This new genus belongs to the group of amblypygous genera (subtribe Amblytelina sensu Heinrich, 1967a ) of the tribe Ichneumonini . It is characterized by the structure of the head and propodeum, and in males also by the strongly serrate flagellum (similar to Pristiceros Heinrich, 1961 ). In the keys to the Oriental Ichneumoninae ( Townes et al. 1961) and Palaearctic genera of Amblytelina ( Tereshkin 2011) , this genus runs to Hepiopelmus Wesmael, 1845 , but strongly differs by several morphological features such as carination of propodeum, lack of median tubercle of area basalis, and strongly serrate flagellum of males.

Overall, the new genus is similar to Hepiopelmus and Tricholabus Thomson, 1894 in having a pentagonal areolet; notauli vestigial at anterior end; hind margin of metanotum with lateral projections; gastrocoeli rather large and deep, thyridia present; propodeum without apophyses; hind tibiae without white rings; 2 nd and 3 rd sternites with longitudinal fold or unsclerotized predominantly. These three genera can be distinguished by the following key.

Key to similar genera, Serratichneumon gen. nov., Hepiopelmus and Tricholabus

1. Propodeum of female without distinct carinae. Scutellum slightly convex. 4 th sternite predominantly sclerotized. Hypopygium ( Figs 3–4 ) not distally produced, only slightly concave in the middle. Flagellum of male without tyloids, and strongly serrate. Oriental ..................................................... ...................................................................................... Serratichneumon Riedel & Sheng gen. nov.

– Propodeum of female with distinct carinae. Scutellum strongly convex. 4 th sternite predominantly unsclerotized. Hypopygium more or less medially produced. Flagellum of male with or without tyloids, and not serrate ...................................................................................................................... 2

2. Occipital carina joining hypostomal carina at base of mandible. Thyridium narrower than the distance between thyridia. Area basalis with tubercle. Area superomedia approximately square, or narrowed posteriorly. Flagellum of male with tyloides.Hypopygium of males slightly produced medio-distally, but without a knoll-shaped swelling. Palaearctic and Oriental ............ Hepiopelmus Wesmael, 1845

– Occipital carina joining hypostomal carina above base of mandible. Thyridium wider than the distance between them. Area basalis of propodeum without tubercle. Area superomedia hexagonal. Flagellum of male without tyloides. Hypopygium of male slightly produced medio-apically with characteristic knoll-shaped swelling. Holarctic ..................................... Tricholabus Thomson, 1894

Figures

Figs 12–14. Serratichneumon maculatus Sheng & Riedel gen. et sp. nov.12–13. Holotype, ♀ (CBDPC). 12. Apical portion of metasoma, lateral view. 13. Apical portion of metasoma, ventral view.14. Paratype, ♂ (CBDPC), head, anterior view.

Figs 1–3. Serratichneumon maculatus Sheng & Riedel gen. et sp. nov., holotype, ♀ (CBDPC). 1. Habitus, lateral view. 2. Head, anterior view. 3. Mandibles.

Figs 4–7. Serratichneumon maculatus Sheng & Riedel gen. et sp. nov., holotype, ♀ (CBDPC). 4. Head, lateral view. 5. Head, dorsal view. 6. Mesoscutum and scutellum, dorsal view.7. Mesosoma, lateral view.