Megacoxa synchrotron Brazidec 2024
Creators: name: Vilhelmsen, Lars
name: Wu, Qiong
name: Wang, Zhen
name: Gao, Tai-Ping
name: Ren, Dong
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Australomicroprotopidae
Megacoxa
Megacoxa synchrotron

description: † Megacoxa synchrotron Brazidec et al., 2024
Fig. 5
Diagnosis
See Brazidec et al. (2024).
Material examined
MYANMAR • ♀; Kachin State, Myitkyina District, Hukawng Valley; [26°20′ N, 96°36′ E]; unnamed horizon, mid-Cretaceous, upper Albian to lower Cenomanian, 98.79± 0.62 Ma (Cruickshank & Ko 2003; Shi et al. 2012); CNU-HYM-MA-2016208.
Description
Female
BODY. Length (except ovipositor) 5.4 mm, fore wing length 3.4 mm. Specimen in slightly gritty amber piece together with small beetle (Coleoptera) and midge (Diptera); wasp well preserved except for right foreleg cut off at base of tibia and ovipositor (Fig. 5A) cut off approx. 0.5 mm from tip of abdomen.
HEAD. Wider than long, head capsule without prominent sculpture or setation; eyes oval (Fig. 5B), higher than long, without postocular carina; antennal insertions in depressions, frons overhangs them above; occipital carina well developed (Fig. 5A), crenulate, area around occipital foramen deeply concave; clypeus short and wide, triangular with tip between antennal insertions; antenna (Fig. 5B) slightly shorter than head + mesosoma combined, with short globular scapus and short flat pedicellus, antennomeres 3–14 flattened (probably an artefact), antennomeres 3–6 longer than 7–13, antennomere 14 approx. twice as long as wide, strongly tapered apically; labrum a small narrow flap below clypeus, concealed when mandibles are closed; mandibles broad, with three teeth (Fig. 5B) each, apical tooth longest.
MESOSOMA. With elongate, extended propectus (Fig. 5A–B); pronotum narrow medially, triangular laterally; fore femur spindle-shaped, fore tibia slender, with elongate, curved calcar; mesoscutum strongly arched in lateral view, angled between vertical anterior surface and horizontal surface; horizontal surface flat, level with mesoscutellum, not prominently sculptured; median mesoscutal sulcus (Fig. 5A) distinct, crenulate, extends to transscutal articulation; axillae distinct, triangular, abut medially, separated from mesoscutellum by oblique foveate scutoscutellar sulcus; mesoscutellum flat, smooth, pointed anteriorly, rounded posteriorly; mesosoma difficult to observe laterally because of position of legs and curvature of amber piece; mid femur spindle-shaped, mid tibia slender; hind leg much larger than fore and mid legs, hind femur strongly swollen, hind tibia (Fig. 5C) strongly expanded distally, widest at approx. two-thirds from proximal end, with distinct fringe of setae distally on median ventral margin, two apical tibial spurs inserted just distally of fringe, inner spur longer than outer; hind basitarsomere approx. equal in length to remaining tarsomeres; tarsal claws slender, simple.
WINGS. Fore wing (Fig. 5D) hyaline with veins C, R1, Sc+R, M+Cu, A, Rs+M, Rs, M and Cu fully pigmented; Rs+M aligned with M+Cu; medial cell wide distally; Rs present between Rs+M and r-rs, closing first submarginal cell; marginal cell narrow, closed in straight line by Rs; hind wing could not be observed.
METASOMA. 1.68 × as long as mesosoma, fusiform, with weak sculpture and setation in ventral view; sternum 2 tapering anteriorly, broadening posteriorly to broadest point of metasoma, approx. twice as long as sternum 3; sternum 7 strongly tapered apically, folded over medially along longitudinal axis; base of ovipositor (Fig. 5A) extends straight from dorsal part of metasomal tip and beyond tips of wings.
Male
See Brazidec et al. 2024.
Remarks
† Megacoxa synchrotron was described from a male and the holotype was deposited in Phyletisches Museum Jena, Germany (CASENT0753237; Brazidec et al. 2024: figs 2f, 8). The female we describe here resembles the holotype in a number of features: the antennal configuration, the crenulate median mesoscutal sulcus, the medially abutting axillae, the uniquely enlarged hind tibia (Fig. 5C; Brazidec et al. 2024: fig. 8a). The wing venation is virtually identical in the holotype and the present female (compare Fig. 5D with fig. 2f in Brazidec et al. 2024). The main difference between the two specimens is in their size, the female being almost twice as long as the holotype. However, such sexual dimorphism is not unusual in wood-living wasps (L. Vilhelmsen, pers. obs.). In most of the phylogenetic analyses (Fig. 1), the female specimen CNU-HYM-MA-2016208 comes out in a polytomy with the three previously described species of † Megacoxa, including † M. synchrotron.
description: Published as part of Vilhelmsen, Lars, Wu, Qiong, Wang, Zhen, Gao, Tai-Ping & Ren, Dong, 2025, Three new species of the long-tailed wasp genus † Megacoxa Brazidec et al., 2024 (Hymenoptera: Megalyridae) from Kachin amber, pp. 238-254 in European Journal of Taxonomy 976 (1) on pages 248-250, DOI: 10.5852/ejt.2025.976.2793, http://zenodo.org/record/14981651