Chelonastichus Ranjith & Quicke 2025, gen. nov.
Creators: name: Ranjith, Avunjikkattu Parambil
name: Quicke, Donald L. J.
name: Chansri, Kittipum
name: Butcher, Buntika A.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Eulophidae
Chelonastichus

description: Chelonastichus Ranjith & Quicke gen. nov.
Figs 1, 2, 3
Type species.
Chelonastichus hanssoni Ranjith & Quicke, sp. nov.
Comparative diagnosis.
The new genus Chelonastichus can be distinguished from all other eulophids by the autapomorphic character, Gt 5 modified into a distinct carapace. The new genus is tentatively placed in the subfamily Tetrastichinae based on the following characters; axillae strongly angularly advanced, postmarginal vein of fore wing absent and submarginal vein of fore wing not smoothly continuous with parastigma. Most tetrastichines have submedian longitudinal grooves on mesoscutellum, but in Chelonastichus, gen. nov., these are almost indistinct. Apart from the metasomal carapace, the new genus distantly related to the following genera, Aceratoneura Girault from Australia and the widespread Old World genus Sigmophora Rondani based on the presence of transverse carina behind lateral ocelli (Bouček 1988). It differs from Aceratoneura by the number of funicular segments of the antennae and from Sigmophora by the number of anelli, and from both through the enlarged Gt 5. In the key to European eulophid genera (Graham 1987) the new genus runs to Nesolynx Ashmead in having scattered setae on the middle lobe of the mesoscutum, mesoscutellum without submedian grooves and vertex with transverse ridge. In addition to its greatly enlarged and coarsely sculptured Gt 5, Chelonastichus, gen. nov., differs from Nesolynx in not having a metallic tinge on head and mesosoma, antennal funiculars longer than wide, not distinctly transverse and mesoscutellum with an anterior row of strong setae.
Description.
Female. Head. Antennae attached slightly below middle of frons, halfway between anterior ocellus and mouth margin; scape not reaching to upper level of vertex (Fig. 1 B); pedicel stout (Figs 1 E, 2 E); antenna with two anelli and three funiculars, and three clavomeres with a weak constriction between C 1 and C 2 (Fig. 2 E). Head with malar sulcus complete and straight (Figs 1 E, 2 E); without subocular fovea and genal carina (Figs 1 E, 2 E); clypeal margin convex without teeth (Fig. 1 B, C); mandible bidentate, upper tooth wide, lower tooth acute (Fig. 1 B, C); frons shiny, transversely striae antero-laterally associated with fine reticulations and with transverse carina medially (Fig. 1 B, D); vertex finely reticulate with more or less complete transverse carina, rest of vertex unevenly sculptured (Fig. 1 D); occipital margin rounded (Fig. 1 D).
Mesosoma. Pronotum with long setae, distinctly reticulated and shiny, without transverse carina (Fig. 1 D, F). Mesoscutum reticulated with a distinct median groove in anterior 2 / 3 rd; with one pair of long and strong adnotaular setae posteriorly (Fig. 1 F). Notauli complete without crenulations (Fig. 1 F). Axillae advanced by half their length in front of transscutal articulation (Fig. 1 F). Mesoscutellum slightly convex in lateral view; with indistinct submedian grooves in posterior half; with sublateral grooves; with four pairs of setae sublaterally and a single pair of setae antero-medially; frenal groove present, wide and crenulated (Figs 1 F, 2 A). Dorsellum smooth and shiny, without median carina or groove (Fig. 2 B). Propodeum with a wide and short fovea just behind dorsellum and a complete and strong narrow median carina that expands to a triangular shape posteriorly; without paraspiracular carinae; spiracles large, rounded and not covered by a flap; callus with three setae; plica distinct in apical half of propodeum (Fig. 2 B). Wings. Fore wing entirely hyaline (Fig. 2 F); with four setae on the dorsal surface of a submarginal vein (Fig. 3 D, E); postmarginal vein absent (Figs 2 F, 3 F); costal cell very narrow, 13.0 × as long as wide (Figs 2 F, 3 D, E); speculum open (Figs 2 F, 3 D, E); stigmal vein with four companiform sensillae (Fig. 3 F); posterior margin of hind wing with long setae (Fig. 3 E). Legs. Coxae with weak reticulation (Fig. 1 A).
Metasoma. Petiole transverse, with irregular sculpture, smooth medially (Fig. 2 B). Gaster 2.0 × as long as wide, setose (Figs 1 A, 2 C, D, 3 A – C). Gt 1 smooth faintly reticulated, sparsely setose laterally (Fig. 2 D); Gt 2–4 faintly reticulated with transverse rows of setae (Fig. 2 C, D); Gt 5 modified into a carapace, strongly reticulate without interspaces, setose (Figs 1 A, 2 C, D, 3 A – C); Gt 6–7, strongly reticulate and retracted under Gt 5 (Fig. 3 A, B). Gt 7 produced into a triangular process posteriorly (Fig. 3 B). Ovipositor sheaths setose throughout (Fig. 3 A – C). Female hypopygium reaching half the length of gaster, acute in lateral view (Fig. 3 A, C).
Distribution.
Oriental region (Thailand).
Hosts / biology.
Unknown.
Etymology.
The genus name derived from a combination of a generic name from the family Braconidae, ‘ Chelonus ’ because of the first instance of carapace-like metasoma in the family Eulophidae and ‘ astichus ’ from the subfamily name Tetrastichinae where this genus is provisionally included.
description: Published as part of Ranjith, Avunjikkattu Parambil, Quicke, Donald L. J., Chansri, Kittipum & Butcher, Buntika A., 2025, Chelonastichus Ranjith & Quicke, gen. nov. (Hymenoptera, Eulophidae, Tetrastichinae) from Thailand: the first eulophid with a metasomal carapace, pp. 499-507 in Journal of Hymenoptera Research 98 on pages 499-507, DOI: 10.3897/jhr.98.144864