Eucinetus panghongae Li & Cai, 2024

Li, Yan-Da, Engel, Michael S., Huang, Di-Ying & Cai, Chen-Yang, 2024, Three new species of the extant genus Eucinetus from mid-Cretaceous amber of northern Myanmar (Coleoptera: Eucinetidae), Zootaxa 5492 (2), pp. 214-230 : 220-222

Eucinetus panghongae Li & Cai sp. nov.

( Figs 5–8 )

Material. Holotype, NIGP203940 , male.

Etymology. The species is named after the coleopterist Dr. Hong Pang.

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. Labrum emarginate ( Fig. 7A ). Apical maxillary palpomere asymmetrical, apically with aciculate tip ( Fig. 7A ). Antennomere 3 about 0.85 times as long as 4 ( Fig. 7A ); antennomere 11 about 2.5 times as long as wide ( Fig. 7B ). Scutellar shield rounded at apex ( Fig. 7F ). Elytra about 1.8 times as long as combined width. Hind wings present. Metanepisternum at least twice as long as wide. Meso- and metatibiae at most with only one or two spines along outer edge ( Figs 6B , 7E ). Mesotibial spurs large; both distinctly stouter than spines along apical fringe of mesotibia ( Fig. 7D ). Metatibial spurs equal ( Fig. 7F ).

Description. Body fusiform and slender, about 1.6 mm long, 0.7 mm wide; surface with fine short setae.

Head deflexed against ventral side of prothorax; entirely concealed from above by pronotum. Compound eyes weakly emarginate anteriorly, with interfacetal setae. Antennae 11-segmented, filiform; antennomere 2 elongate; antennomeres 3–10 moderately longer than wide; antennomere 3 about 0.85 times as long as 4; antennomere 11 about 2.5 times as long as wide. Frontoclypeal suture straight anteriorly and with distinct anterolateral angles. Labrum weakly narrowed toward apex, apically emarginate. Mouthparts non-suctorial. Apical maxillary palpomere asymmetrical, apically with aciculate tip.

Prothorax widest at base. Lateral pronotal carinae complete, simple. Pronotal disc simple. Procoxae obliquely oriented, well-projecting, narrowly separated. Scutellar shield rounded at apex. Elytra about 1.8 times as long as combined width; transversely strigulate; sutural stria present; epipleuron narrow, incomplete. Hind wings present. Metaventral posterior process with distinct median discrimen. Metanepisternum at least twice as long as wide. Metacoxae contiguous; metacoxal plates well-developed and greatly enlarged.

Mid and hind legs with fringe of spines at apices of tibiae and tarsomeres; fore legs without apical fringes of spines. Meso- and metatibiae at most with only one or two spines along outer edge. Mesotibial spurs large; both distinctly stouter than spines along apical fringe of mesotibia. Metatibial spurs equal. Tarsi 5-5-5, simple. Meso- and metapretarsal claws with accessory lobes ( Fig. 7G ).

Abdomen with six ventrites. Posterior margin of ventrite 5 subtruncate, not emarginate.

Remarks. The sternite VIII of NIGP203940 (and also NIGP203939) is densely covered with setae like the preceding ventrites ( Fig. 7F ). It should be normally exposed when alive, representing the sixth ventrite. In some recent comprehensive coleopteran compendia, the abdomen is described as having only five ventrites for the whole Eucinetidae ( Lawrence & Ślipiński 2013; Leschen 2016). However, the sternite VIII is actually commonly exposed in many extant members of Eucinetus ( Vit 1977a) .

Figures

FIGURE 5. General habitus of Eucinetus panghongae Li & Cai sp. nov., holotype, NIGP203940, under incident light. A, Dorsal view. B, Ventral view. Scale bars: 500 μm.

FIGURE 6. General habitus of Eucinetus panghongae Li & Cai sp. nov., holotype, NIGP203940, under confocal microscopy. A, Dorsal view. B, Ventral view. Scale bars: 500 μm.

FIGURE 7. Details of Eucinetus panghongae Li & Cai sp. nov., holotype, NIGP203940, under confocal microscopy. A, Head, dorsal view. B, Antennae. C, Mid leg. D, Fore and mid legs. E, Mid leg. F, Abdominal apex, ventral view. G, Hind leg. H, Scutellar shield, dorsal view. I, Abdominal apex, dorsal view.Abbreviations: a2–11, antennomeres 2–11; cl, clypeus; lb, labrum; mstb, mesotibia; mttb, metatibia; mtts, metatarsus; mtv, metaventrite; mxp, maxillary palp; pts, protarsus; sc, scutellar shield; v5–6, ventrites 5–6. Scale bars: 100 μm.

FIGURE 8. X-ray microtomographic reconstruction of Eucinetus panghongae Li & Cai sp. nov., holotype, NIGP203940. A, Dorsal view. B, Ventral view. C, Lateral view. Scale bar: 500 μm.