Syzeuctus flavitarsis Watanabe & Riedel, 2024, sp. nov.
Creators: name: Watanabe, Kyohei
name: Riedel, Matthias
Publisher: name: Zenodo
Year: 2024
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Ichneumonidae
Syzeuctus
Syzeuctus flavitarsis

description: Syzeuctus flavitarsis sp. nov.
(Figs 1 D, 2 D, O, 8 A–H, 9 A–C)
Type series. Holotype: F, JAPAN, Honshu, Tochigi Pref., Nasushiobara City, Ohkawa-rindo, 11–25. VIII. 2010, T. Nakayama leg., MsT (KPMNH). Paratypes: JAPAN: [Honshu] 1 F, Yamagata Pref., Mamurogawa Town, 21. VIII. 2012, Y. Matsubara & K. Fukuda leg., MsT (ZSM); 1 F, Shiga Pref., Otsu City, Biwako-Ballay, 29. VI. 2011, M. Ito leg. (KPMNH); 1 F, Nara Pref., Totsukawa Vil., Mt. Shakagatake, 20. VII.–11. VIII. 2013, S. Fujie & T. Hirooka leg. (OMNH); 1 F, Tottori Pref., Wakasa Town, Mt. Hyonosen, 6. VIII. 2011, K. Watanabe leg., light trap (KPMNH); [Shikoku] 1 M, Ehime Pref., Uchico Town, Mt. Kasatori, 30. VI. 2012, E. Yamamoto leg. (EUM).
Description. Female (n = 5). Body polished and covered with punctures and silvery setae; length 8.1–9.2 (HT: 9.1) mm. Setae on head and mesosoma not exceptionally long and erect.
Head 0.6 × as long as wide. Combined length of clypeus and face 1.0–1.05 (HT: 1.05) × facial width. Clypeus smooth except for dorsal margin sparsely punctate, slightly convex in lateral view, without central transverse ridge. Face densely punctate, slightly convex medially in lateral view, without a pair of convexities just above of each anterior tentorial pit. Frons slightly concave, without horns or convexities. Malar space 0.5 × as long as basal mandibular width. Genal carina lamella-like ventrally, reaching mandibular base. POL 1.5–1.7 (HT: 1.7) × as long as OD. OOL 1.2–1.4 (HT: 1.2) × as long as OD. Temple weakly roundly narrowed behind eye in dorsal view (Fig. 8 E). Antenna with 42–45 (HT: 42) flagellomeres. FL I 4.3–4.6 (HT: 4.6) × as long as maximum depth in lateral view and 1.5–1.6 (HT: 1.6) × as long as FL II. Preapical flagellomere 1.1 × as long as maximum width.
Mesosoma coarsely and densely punctate, 1.45 × as long as maximum height. Pronotum with small smooth area just behind of epomia. Epomia present, its dorsal end not reaching dorsal margin. Mesopleuron densely punctate; speculum with a large smooth area (Fig. 2 F). Punctures on upper part of mesopleuron irregular and sparser than on lower part. Epicnemial carina present latero-ventrally and ventrally, its dorsal end remote from anterior margin of mesopleuron, without angulation (Fig. 1 D). Dorsal surface of propodeum without transverse rugae. Posterior transverse carina of propodeum largely absent medially, obsolete laterally. Fore wing length 7.0–7.3 (HT: 7.0) mm. Areolet receiving vein 2m-cu slightly basal to the outer angle, petiolated anteriorly; petiole as long as areolet (Fig. 8 G). Fore wing vein 1cu-a subvertical, slightly postfurcal to vein M&RS. Nervellus reclivous, intercepted posterior to the middle. Hind femur 5.5–6.0 (HT: 5.8) × as long as maximum depth in lateral view. Ratio of length of first to fifth hind tarsomeres 4.2–4.3 (HT: 4.2): 2.0: 1.4: 0.8: 0.9. Hind tarsal claws simple except for minute subbasal teeth, strongly bent apically (ca. 90°) (Fig. 2 D).
Metasoma. T I 2.2–2.4 (HT: 2.4) × as long as maximum width, finely punctate laterally, smooth medially. T II 1.25–1.5 (HT: 1.5) × as long as maximum width, finely and densely punctate. T III to T V coriaceous with fine and dense punctures. Ovipositor sheath 2.0 × as long as hind tibia, ca. 0.8 × as long as fore wing, and shorter than body length.
Colouration (Figs 8 A–H). Body (excluding wings and legs) black. Clypeus, mandible except for teeth, malar space, a pair of small yellow spots below antennal sockets (sometimes absent as Fig. 8 D), orbits on face, frons, vertex and gena, and palpi yellow. Antenna blackish-brown to reddish-brown. Scape and pedicel usually partly tinged with yellow ventrally. Two spots of collar, a L-shape marking of dorsal margin of pronotum, a pair of antero-lateral markings and a median marking of mesoscutum, subtegular ridge, antero-dorsal and postero-ventral spots of mesopleuron, scutellum except for a median black spot, postscutellum, posterior spot of metapleuron, a pair of antero-lateral spots of propodeum, and a posterior triangle marking of propodeum yellow. Scutellum sometimes entirely yellow. Metasomal tergites black except for a basal band of T I and posterior margins of T I to T V yellow. Membranous parts of metasomal sternites largely yellow. Subgenital plate blackish-brown, usually partly tinged with yellowish-brown. Ovipositor reddish-brown. Wings hyaline. Apical clouded area of fore wing slightly to weakly present. Veins and pterostigma blackish-brown except for yellowish-brown wing base. Fore and mid legs yellow; mid coxa partly tinged with blackish-brown basally. Hind coxa black except for a dorsal spot and apex yellow to yellowish-brown. Hind trochanter black to blackish-brown. Hind trochantellus yellow. Hind femur reddish-brown except for apex tinged with yellow. Hind tibia and tibial spurs ivory except for apical part of tibia blackish-brown. Hind tarsus ivory to yellowish white part except for black fifth tarsomere.
Male (n = 1). Similar to female (Figs 9 A–C). Body length 7.8 mm. Malar space 0.8 × as long as basal mandibular width. Tergal spiracles not enlarged (Fig. 2 O). Ratio of length of hind first and second tarsomeres 4.0: 2.0. Face entirely yellow. Bases of T II to T IV each with yellow marking.
Distribution. Japan (Honshu and Shikoku).
Etymology. The specific refers to the yellowish (flavi-) coloration of first to fourth hind tarsomeres.
Bionomics. Unknown.
Remarks. In the key provided by Riedel (2021), the female runs to couplet 37 (S. flavomaculatus) but differs by the T I 2.2–2.4 × as long as maximum width (1.95 × in S. flavomaculatus), the ovipositor shorter than fore wing (longer than fore wing in S. flavomaculatus), and hind tarsus ivory except fifth tarsomere (reddish-brown in S. flavomaculatus). This species closely resembles S. yamatonis sp. nov. but can be distinguished by the punctuation of mesopleuron and the colour patterns of hind leg and metasomal tergites (see key above).
description: Published as part of Watanabe, Kyohei & Riedel, Matthias, 2024, Revision of the genus Syzeuctus Förster, 1869 (Hymenoptera, Ichneumonidae, Banchinae) from Japan, pp. 35-71 in Zootaxa 5496 (1) on pages 47-49, DOI: 10.11646/zootaxa.5496.1.2, http://zenodo.org/record/13331013