Megacoxa, 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. Genus † Megacoxa gen. nov.

Type species.

† Megacoxa janzeni sp. nov.

Etymology.

The genus name refers to the size of the metacoxa, which is the key diagnostic feature of the genus; besides, the prefix Mega - alludes to the family name Megalyridae . Gender feminine.

Diagnosis.

Compound eye oval; scape wider than long; thin occipital carina slightly crenulate. Parapsidal line present and located on posterolateral part of mesoscutum (Figs 6C , 7B and E ); inner axillar groove crenulate (Fig. 8F ). Fore wing venation with R1, M+Cu, Sc+R, A and Cu fully pigmented; A connected to medial cell with cu-a; Rs closing marginal cell without bend (Figs 2D-F ). Metacoxa much enlarged, with dorsal surface rounded to angular, outer metacoxal surface posteriorly foveate, inner metacoxal surface almost entirely accommodated in anterolateral, shallow concavity of metasoma (Figs 6C , 7B , 8C and G ). Metatibia and metabasitarsus with ventral row of comb-like setae; two mesotibial and two metatibial spurs (Figs 6A and 7A ). Metasoma slightly shorter than mesosoma, tergites and sternites beveled (Figs 6B and 7A ).

Comments.

The enlarged metacoxa accommodated in the anterior metasomal concavity is the key diagnostic feature for † Megacoxa gen. nov. This condition is present in all five specimens assigned to this genus and the metacoxae are clearly symmetrical in the synchrotron-scanned specimen, thus ruling out a preservational artefact.

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 6. † Megacoxa chandrahrasa gen. et sp. nov., mid-Cretaceous, Kachin amber. A holotype female IGR. BU- 068, habitus in dorsal view; B habitus in lateral view; C mesosoma in lateral view; D head in frontal view; E paratype female CNU-HYM-MA 2016207, habitus in lateral view; F head and mesosoma in dorsolateral view; G hind legs; H ovipositor and its sheaths. Scale bars: 1 mm (A, B, E, F); 0.5 mm (C, D, G, H). Abbreviations: Cx = hind coxa; MeS = mesometapectal sulcus; MMS = median mesoscutal sulcus; OC = occipital carina; PpL = parapsidal line; sp = anterior thoracic spiracle.

Figure 7. † Megacoxa janzeni gen. et sp. nov., mid-Cretaceous, Kachin amber; A holotype female IGR. BU- 069, habitus in lateral view; B mesosoma in lateral view; C head in frontal view; D paratype male NIGP 203547, habitus in lateral view; E head and mesosoma in lateral view (scale bars: A, D = 2 mm; E = 1 mm; B, C = 0.5 mm). Abbreviations: Cx = hind coxa; MeS = mesometapectal sulcus; PpL = parapsidal line; sp = anterior thoracic spiracle.

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.