Megacoxa mjoelner Vilhelmsen, Wu, Wang, Gao & Ren, 2025, sp. nov.
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 mjoelner

description: † Megacoxa mjoelner sp. nov.
urn:lsid:zoobank.org:act: 215840BF-F89F-4A1B-98F1-A738E89B3299
Fig. 4
Diagnosis
Body comparatively slender (Fig. 4A), metasoma longer than mesosoma (shorter in † M. chandrahrasa and † M. gungner sp. nov.). Antennae shorter than head + mesosoma (longer in † M. brazideci sp. nov.). Median mesoscutal sulcus smooth (crenulate in † M. synchrotron), axillae not contiguous (contiguous in † M. brazideci). Hind coxa without carina or foveae along posterior margin (coxa carinate and foveate in † M. janzeni and † M. synchrotron).
Etymology
The new species takes its name after Mjølner (or Mjolnir), the magic hammer that was the chief weapon and primary attribute of Thor, the thunder god in Norse mythology. Like the ovipositor in † M. mjoelner sp. nov. (see below), the shaft of the hammer was shorter than it was originally supposed to be, due to the interference of the trickster god Loke in the form of a fly; he viciously stung the dwarven smith Brokk as Mjølner was being finalized, thus confirming the timeless malevolence of Diptera.
Type material
Holotype
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-2016209.
Description
Female BODY. Length (except ovipositor) 4.3 mm, fore wing length 3.3 mm, ovipositor length 1 mm as preserved (Fig. 4A), probably broken (see below). Specimen in mostly clear amber piece, with small midge (Diptera) syninclusion. Exudate covers lower part of head and a few diffraction planes extend from dorsal part of mesosoma.
HEAD (Fig. 4D). Globular, slightly wider than long, without prominent sculpture or setation; eyes oval, cover most of lateral surface of head; ocelli situated on top of head in approx. equilateral triangle; postocular carina absent; occipital carina well developed (Fig. 4D), smooth, area around occipital foramen deeply concave; antenna clearly shorter than head + mesosoma combined, scapus curved, pedicellus short, antennomeres 3–13 cylindrical (Fig. 4D), slightly longer than wide, decreasing in length distally, antennomere 14 approx. twice as long as wide, tapering distally; mouthparts difficult to observe, mandible apparently broad, teeth not visible; short palps can be observed.
MESOSOMA. With elongate, extended propectus; pronotum narrow medially, triangular laterally, with anterior thoracic spiracle in notch in lateral margin (Fig. 4C); fore femur spindle-shaped, fore tibia slightly expanded distally (Fig. 4D), 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 distinct (Fig. 4B–C), smooth, extends to transscutal articulation; axillae distinct, triangular, not abutting medially, separated from mesoscutellum by oblique foveate scutoscutellar sulcus; mesoscutellum flat, smooth with small punctures, diamond-shaped; mesopleuron smooth, with depression medially, mesopleuro-metapleural sulcus distinct, crenulate (Fig. 4C); mid femur spindle-shaped, mid tibia slender, with two short apical spurs; hind coxa broad, with carina along posterior margin but without foveae; hind femur spindle-shaped; hind tibia (Fig. 4A) flattened, expanded distally, without fringe of setae, with two apical spurs of subequal length, inner spur shorter than distal tibial width; hind basitarsus slightly longer than remaining tarsomeres, tarsal claws simple, slender.
WINGS. Fore wing (Fig. 4B) 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 (Fig. 4A). 1.27 × as long as mesosoma, slender, fusiform, without prominent sculpture or pilosity; metasomal segment 2 largest, metasoma widest there; sternum 7 tapered apically, folded over medially along longitudinal axis; ovipositor (Fig. 4A) bent ventrally, apparently broken, 1 st and 2 nd valvulae separated at tip and no teeth observed on tip of 2 nd valvula.
Male
Unknown.
Remarks
† Megacoxa mjoelner sp. nov. mostly resembles † M. brazideci sp. nov., from which it differs in having a smooth frons, shorter antennae and the axillae not being contiguous.
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 246-248, DOI: 10.5852/ejt.2025.976.2793, http://zenodo.org/record/14981651