Siccibythus robustus Wang, Rasnitsyn, Perkovsky & Vilhelmsen 2025, sp. nov.
Creators: name: Wang, Zhen
name: Rasnitsyn, Alexandr P.
name: Perkovsky, Evgeny E.
name: Vilhelmsen, Lars
name: Gao, Taiping
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Scolebythidae
Siccibythus
Siccibythus robustus

description: Siccibythus robustus Wang, Rasnitsyn, Perkovsky & Vilhelmsen sp. nov.
Diagnosis.
The length of the scape is less than 0.3 times the length of the flagellum. Fore wing with 2 Rs distal of r-rs several times as long as r-rs; Cu nebulous. Fore tibial spur long, thin and acute apically. Metabasitarsus longer than tarsomeres 2–4 combined. Propodeum outline angular. Anterior outline of 1 st metasomal tergum somewhat angular.
Etymology.
The species is named after the Latin adjective robustus, meaning “ thick ” and referring to the thick fore femur.
Type material.
Holotype • female. No. CNU-HYM-MA 2016212. A well-preserved and complete specimen (Figs 1, 2). Paratype • male. No. CNU-HYM-MA 2016213. A well-preserved and complete specimen (Figs 3, 4).
Type locality and horizon.
The amber specimens were collected from Kachin, northern Myanmar, lowermost Cenomanian, mid-Cretaceous, which was dated at 98.79 ± 0.62 Ma (Cruickshank and Ko 2003; Shi et al. 2012).
Description.
Female. Head globose, with eyes bulging, occupying most of lateral parts of head (except for wide, convex temples), almost reaching mandibular bases, occipital carina complete, reaching hypostomal carina well behind mandibular base, vertex and frons narrow, longer than wide, ocelli in small acute triangle well distant from eyes, interantennal space flat, clypeus short, simple. Antenna slender, with 12 antennomeres in female (13 in male), each antennomere is approximately 1–2 times longer than wide, scape slightly longer than pedicel and first flagellomere combined, pedicel longer than first flagellomere, flagellomeres slightly shortening gradually toward apex except for shorter first flagellomere and longer apical segment (Fig. 1 B). Labrum not visible externally, mandibles small, overlapping, maxillary and labial palps not visible (paratype can be observed mandibles with three teeth, maxillary palp with four palpomeres visible, three apical long, narrow).
Pronotum posterior margin extended, with pronotum accounting for 0.4 times the length of mesosoma, pronotum short declivitous part delimited by transverse groove posteriorly. Propleura long, slender, abutting throughout ventrally. Mesoscutum convex between notauli; notauli complete, parapsides and lateral edges incomplete; notauli widely spaced anteriorly, converging to almost meet posteriorly; transscutal articulation distinct; mesoscutellum triangular, narrow, the length is 0.4 times its maximum width, weakly convex, carinate laterally. Meso- and metapleuron smooth, metapleuron delimited from propodeum with incomplete row of pits (Fig. 2 A, B). Metanotum short, with indistinct metascutellum in female (metanotum short, with distinct metascutellum in male). Propodeum with clear dorsal and posterior surfaces meeting in angle, dorsal with longitudinal and one transverse carinae, posterior surface with lateral longitudinal carinae, sublateral longitudinal carinae and supracoxal transverse carinae (Fig. 2 B).
Fore wing distal of basal veins (1 Rs and 1 M), r-rs and 1 cu-a without tubular veins, except for pterostigma and half section of 2 Rs distal of r-rs, all other distal veins nebulous in female (fore wing distal of basal vein (1 Rs and 1 M) and cu-a with no tubular veins, except for pterostigma, r-rs and most of Rs distal of r-rs, all other veins nebulous in male). Pterostigma prominent, longer than wide; vein 1 Rs straight, shorter than 1 M, arise from Sc + R just proximal to pterostigma; 1 cu-a shorter than 1 M, placed distinctly before it, parallel to 2 cu-a; Cu parallel to A; vein A extending distal to 1 cu-a, and distal part tubular, extending distal to 2 cu-a as nebulous vein, both 1 cu-a and 2 cu-a reaching A; r-rs slightly curved, arising beyond midlength of pterostigma; r-m not present (Fig. 1 C). Hind wing with thin, tubular veins Rs arising from Sc + R; A present; other veins not visible. Seven hamuli present.
Fore coxa swollen, triangular, nearly as long as wide; fore trochanter short, fore trochantellus not visible in female (fore trochantellus trapezoidal, the ratio compared to the length of the fore femur is approximately 1: 17 in male); fore femur swollen in middle, twice as long as wide (calcar long, thin, gently curved and acute apically in male); fore tibia nearly as long as femur; fore tarsus shorter than fore tibia, basitarsomere shorter than combined length of remaining tarsomeres in female (basitarsomere longer than combined length of remaining tarsomeres in male). Mid coxa slender, smaller than both fore and hind coxa, twice as long as wide; mid trochanter short, mid trochantellus very short and ring-like, approximately 0.1 times as long as femur; mid femur swollen in middle, twice as long as wide; mid tibia slenderer than femur, three times as long as wide, tibia shorter than femur; mid tarsus nearly as long as mid tibia, basitarsomere shorter than combined length of remaining tarsomeres. Hind coxae elongate, swollen, three times as long as wide, with lamella dorsally, basally in female (no lamella in male); hind trochanter short, bulging dorsally, hind trochantellus very short and ring-like (ca. 0.02 as long as femur); hind femur swollen in middle, nearly three times as long as wide in female (nearly six times as long as wide in male); hind tibia very slender, slightly longer than femur; hind tarsus nearly as long as hind tibia, basitarsomere slightly shorter than combined length of remaining tarsomeres (Fig. 2 C). Claw simple, arolium small. Tibial spur formula 1 / 2 / 2.
First metasomal segment short, tergum node-like, female with anterior outline, low triangular, second metasomal segment longest and highest, following segments gradually smaller, apical metasomal sternum high, with dorsal sides overlapping (Fig. 2 D) (male first metasomal tergum with fore surface convex, dorsal surface short, rather flat, elevated above hind surface; seventh metasomal sternum with two long upcurved teeth).
Measurements (mm).
Holotype female. Total body length (excluding sting and antenna) 3.93; head length 0.47, width 0.61, height 0.53; scape length 0.25, pedicel length 0.13, the first flagellum length 0.08, total flagellum length 0.87; fore wing length 2.22; hind wing length 1.56; fore coxa length 0.30, fore trochanter length 0.57, fore femur length 0.58, fore tibia length 0.55, fore tarsal length 0.32; mid coxa length 0.31, mid trochanter length 0.09, mid trochantellus 0.05, mid femur length 0.50, mid tibia length 0.38, mid tarsal length 0.38; hind coxa length 0.44, hind trochanter length 0.14, hind trochantellus 0.02, hind femur length 0.67, hind tibia length 0.78, hind tarsal length 1.02; the first metasomal segment length 0.28, metasoma length 2.18.
Paratype male. Total body length (excluding antenna) 3.54; head length 0.50, width 0.42, height 0.50; scape length 0.25, pedicel length 0.16, the first flagellum length 0.09; total flagellum length 0.99; fore wing length 1.98; hind wing length 1.47; fore coxa length 0.21, fore trochanter length 0.08, fore trochantellus 0.03, fore femur length 0.50, fore tibia length 0.45, fore tarsal length 0.32; mid coxa length 0.12, mid trochanter length 0.10, fore trochantellus 0.02, mid femur length 0.40, mid tibia length 0.30, mid tarsal length 0.34; hind coxa length 0.28, hind trochanter length 0.12, hind femur length 0.55, hind tibia length 0.60, hind tarsal length 0.57; the first metasomal segment length 0.25, metasoma length 1.62.
Remarks.
The new species is classified in † Siccibythus Cockx & McKellar, 2016 based on the fore wing with no cells closed with tubular veins in its middle and distal part (Rasnitsyn et al. 2020). However, the new species is differentiated from Siccibythus martynovae, S. pallidus and S. oculatus by fore wing with 2 Rs distal of r-rs several times as long as r-rs, basitarsus longer than tarsomeres 2–4 combined (vs. 2 Rs distal of r-rs at most about as long as r-rs, basitarsus not longer than tarsomeres 2–4 combined in S. martynovae, S. pallidus and S. oculatus). It is distinguished from S. musculosus by the following characters: 1) Cu is nebulous (vs. Cu is tubular); 2) calcar long, thin and acute apical (vs. calcar short, bifid apically). It is differentiated from S. paulus by the length of the scape being less than 0.3 times the length of the flagellum (vs. the scape is longer than or equal to 0.3 times of the flagellum). It is distinguished from S. ohmkuhnlei by the following characters: 1) anterior outline of 1 st metasomal tergum somewhat angular (vs. straight); 2) propodeum outline angular (vs. more smoothly curved).
description: Published as part of Wang, Zhen, Rasnitsyn, Alexandr P., Perkovsky, Evgeny E., Vilhelmsen, Lars & Gao, Taiping, 2025, New wasps of † Falsiformicidae from mid-Cretaceous Kachin amber, pp. 1-18 in Journal of Hymenoptera Research 98 on pages 1-18, DOI: 10.3897/jhr.98.136200