Megacoxa synchrotron, Brazidec & Vilhelmsen & Boudinot & Richter & Hammel & Perkovsky & Fan & Wang & Wu & Wang & Perrichot, 2024

Brazidec, Manuel, Vilhelmsen, Lars, Boudinot, Brendon E., Richter, Adrian, Hammel, Joerg U., Perkovsky, Evgeny E., Fan, Yong, Wang, Zhen, Wu, Qiong, Wang, Bo & Perrichot, Vincent, 2024, Unveiling ancient diversity of long-tailed wasps (Hymenoptera: Megalyridae): new taxa from Cretaceous Kachin and Taimyr ambers and their phylogenetic affinities, Arthropod Systematics & amp; Phylogeny 82, pp. 151-181 : 151

3.1.1.3.3. † Megacoxa synchrotron sp. nov.

Figures 2F and 8

Etymology.

The specific epithet is an adjective and refers to the µ-CT technique used at the Deutsches Elektronen-Synchrotron (DESY; Hamburg, Germany) to reconstruct the external surface of the specimen, as well as the internal features for a later study.

Material studied.

Holotype male CASENT0753237; housed in the collection of the Phyletisches Museum Jena , Germany (PMJ).

Type locality.

Noije Bum Hill, Hukawng Valley, Kachin State, Myanmar.

Age.

Upper Albian to lower Cenomanian, mid-Cretaceous.

Diagnosis.

Flagellomeres 1-7 distinctly longer than wide; flagellomeres 8-12 slightly longer than wide (Fig. 8A ); median mesoscutal sulcus crenulate (vs. smooth in † Megacoxa chandrahrasa gen. et sp. nov. and † Megacoxa janzeni gen. et sp. nov.); axillae contiguous medially (Figs 8D and F ; vs. separated medially in † Megacoxa janzeni gen. et sp. nov.); fore wing with medial cell wide (Fig. 2F ; vs. narrow in † Megacoxa chandrahrasa gen. et sp. nov.); posterior margin of metacoxa straight, with large foveae (Figs 8C and G ; vs. rounded with small foveae in † Megacoxa chandrahrasa gen. et sp. nov. and rounded with large foveae in † Megacoxa janzeni gen. et sp. nov.); comb-like setae reduced on the metabasitarsus (Fig. 8A ; vs. more developed on metatibia and metabasitarsus in † Megacoxa chandrahrasa gen. et sp. nov. and † Megacoxa janzeni gen. et sp. nov.).

Description.

Body length 2.89 mm. - Head globular, higher than long (length 0.45 mm; height 0.53 mm), glabrous; frons convex, shagreened; compound eye oval, higher than long, without postocular carina; vertex convex, shagreened; clypeus short, shagreened; subantennal groove present; antenna filiform, reaching metacoxa; scape short and wide (length 0.09 mm); pedicel thinner than scape, shorter than flagellomeres (length 0.07 mm); flagellomeres cylindrical, elongate; flagellomeres 1-7 distinctly longer than wide (length ca. 0.11-0.14 mm); flagellomeres 8-11 slightly longer than wide (length 0.09 mm); flagellomere 12 longest (length 0.16 mm); mandible with three teeth; occipital carina minutely crenulate. - Mesosoma longer than metasoma (length 1.27 mm); mesoscutum (length 0.48 mm) convex, shagreened, divided by crenulate median mesoscutal sulcus; parapsidal lines present; axillae contiguous medially; inner axillar groove crenulate; mesoscutellum diamond-shaped, with blunt posterior margin; pronotum shagreened, with posteromedial part moderately high as viewed laterally; anterior thoracic spiracle not fully surrounded by pronotal cuticle; mesometapectal sulcus crenulate; propodeum carinate, carinae delimiting large fovea on median anterior region, smaller foveae laterally, large foveae on lateral median region and large triangular foveae on posterior region. - Fore wing hyaline, uniformly micropubescent (length 2.04 mm); venation complete with R1, Sc+R, M+Cu, A, Rs+M, Rs, M and Cu fully pigmented; Rs+M aligned with M+Cu; medial cell wide; Rs present between Rs+M and r-rs, closing first submarginal cell; marginal cell narrow, closed in straight line by Rs. - Legs with metacoxa enlarged, posterior margin straight with upper corner angularly produced, bearing row of large foveae along posterior margin; metafemur and metatibia swollen; two mesotibial and two metatibial spurs; metabasitarsus with row of sparse comb-like setae along ventral margin. - Metasoma smooth, fusiform (length 1.17 mm); tergites inserted in bevel.

Figures

Figure 2. Drawings of fore wing venation for the taxa described in the present paper. A † Cretolyra noijebumensis gen. et sp. nov.; B † Cretolyra shawi gen. et sp. nov.; C † Genkyhag innebula gen. et sp. nov.; D † Megacoxa chandrahrasa gen. et sp. nov.; E † Megacoxa janzeni gen. et sp. nov.; F † Megacoxa synchrotron gen. et sp. nov.; G † Kamyristi exfrigore gen. et sp. nov.; H † Kamyristi yantardakhensis gen. et sp. nov. Scale bars: 0.5 mm (A - H).

Figure 8. † Megacoxa synchrotron gen. et sp. nov., holotype male CASENT 0753237, mid-Cretaceous, Kachin amber (E - H: reconstructed using synchrotron radiation-based micro-computed tomography). A habitus in lateral view; B head and anterior mesosoma in lateral view; C metacoxa in lateral view; D habitus in dorsal view; E habitus in dorsal view; F mesosoma in dorsal view; G mesosoma in lateral view; H head in frontal view, with antennae numerically removed. Scale bars: 1 mm (A, D, E); 0.5 mm (B, F, G, H); 0.25 mm (C). Abbreviations: AG = inner axillar groove; Cx = hind coxa; MeS = mesometapectal sulcus; MMS = median mesoscutal sulcus; PpL = parapsidal line; sp = anterior thoracic spiracle.