Archaenosodendron explanatum Li & Cai, 2021

Li, Yan-Da, Tihelka, Erik, Dahan, Loïc, Huang, Di-Ying & Cai, Chen-Yang, 2021, On the Nosodendridae from mid-Cretaceous amber of northern Myanmar (Coleoptera: Nosodendroidea), Zootaxa 5082 (3), pp. 223-244 : 227-230

Archaenosodendron explanatum Li & Cai sp. nov.

( Figs 5–8 )

Material. Holotype, NIGP177613 . The specimen seems to have been damaged before entrapment in amber, with many appendages (mouthparts, antennae, and tarsi) detached and head outstretched.

Etymology. The specific name refers to its flattened body.

Locality and horizon. Amber mine located near Noije Bum Village, Tanai Township, Myitkyina District, Kachin State, Myanmar; unnamed horizon, mid-Cretaceous, Upper Albian to Lower Cenomanian.

Diagnosis. Body flattened and relatively elongate ( Fig. 7 ). Lateral regions of mentum with somewhat longitudinally arranged larger punctures ( Fig. 8B ). Anterior angles of mentum produced anteriorly ( Fig. 8B ). Antennal grooves on prosternum longer than half-length of prosternum in front of coxae ( Fig. 8D ). Outer edge of protibia with about 21–23 denticles/stout setae ( Fig. 8E–G ). Medial and lateral portions of prosternum not separated by a ridge ( Fig. 8D ).

Description. Body flattened and relatively elongate, about 3.67 mm long, 1.4 mm wide.

Head prognathous. Eyes not strongly protuberant. Antennal insertions widely separated and concealed from above. Antennal grooves on head well developed. Frontoclypeal suture absent. Mandibles broad, unidentate. Maxillae with setose lacinia (galea and palp detached). Mentum subtrapezoidal, widest at base; lateral regions with somewhat longitudinally arranged larger punctures; anterior angles produced anteriorly.

Pronotal disc subtrapezoidal, widest at base; anterior margin with very shallow emarginations laterally, slightly protruding medially. Prosternum in front coxae transverse, not extremely shortened; medial and lateral portions of prosternum not separated by a ridge; antennal grooves on prosternum longer than half-length of prosternum in front of coxae; prosternal process relatively slender. Procoxae strongly transverse, well separated. Procoxal cavities broadly open posteriorly.

Scutellar shield triangular, posteriorly acute. Elytra elongate, subparallel in the anterior half, tapering apically; anterior corners almost right. Mesoventrite short, anteriorly with well-developed mesoventral cavity and procoxal rests. Mesocoxal cavities widely separated. Metaventrite transverse, flattened; anterolateral portion with curved line delimiting the impression. Metacoxae narrowly separated.

Femora with groove for receiving tibia. Tibiae expanded distally, with two apical spurs; outer edge of protibia with about 21–23 denticles/stout setae.

Abdomen with five ventrites. Ventrites 1 and 2 with a pair of impressions for receiving hind legs. Anterior margin of ventrites smooth, without notches.

Figures

FIGURE 5. General habitus of Archaenosodendron explanatum Li & Cai sp. nov., holotype, NIGP177613, under incident light. A, Dorsal view. B, Ventral view. Scale bars: 1 mm.

FIGURE 6. General habitus of Archaenosodendron explanatum Li & Cai sp. nov., holotype, NIGP177613, under widefield fluorescence. A, Dorsal view. B, Ventral view. Scale bars: 1 mm.

FIGURE 7. X-ray microtomographic reconstruction of Archaenosodendron explanatum Li & Cai sp. nov., holotype, NIGP177613. A, Dorsal view. B, Ventral view. C, Lateral view. Scale bar: 1 mm.

FIGURE 8. Details of Archaenosodendron explanatum Li & Cai sp. nov., holotype, NIGP177613, under confocal microscopy. A, Head, dorsal view. B, Head, ventral view. C, Head, lateral view. D, Prothorax, ventral view, showing the incomplete antennal groove on prosternum. E–G, Fore legs. H, Mid leg. I, Hind leg. Abbreviations: an1, antennomere 1; md, mandible; msv, mesoventrite; mt, mentum; mtf, metafemur; mttb, metatibia; mtts, metatarsus; mtv, metaventrite; pc, procoxa; pf, profemur; pn, pronotum; ps, prosternum; ptb, protibia; v1,2, ventrites 1,2. Scale bars: 200 μm.