Eucinetus debilispinus 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 : 218-220

Eucinetus debilispinus Li & Cai sp. nov.

( Figs 1–4 )

Material. Holotype, NIGP203939 , male.

Etymology. The specific name refers to its relatively small mesotibial spurs.

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. 3A ). Apical maxillary palpomere narrow and symmetrical, apically acute ( Fig. 3A,B ). Antennomere 3 about 0.70 times as long as 4 ( Fig. 3A ); antennomere 11 about 2.7 times as long as wide ( Fig. 3C ). Elytra about 1.8 times as long as combined width. Hind wings present. Metanepisternum at least twice as long as wide ( Fig. 3D ). Meso- and metatibiae at most with only one or two spines along outer edge ( Figs 2B,C , 3E ). Mesotibial spurs small; the smaller one not distinctly stouter than spines along apical fringe of mesotibia ( Fig. 3E ). Parameres distinctly bowed outwardly ( Fig. 3I ).

Description. Body fusiform and slender, about 1.7 mm long, 0.8 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 slightly longer than wide, somewhat submoniliform; antennomere 3 about 0.70 times as long as 4, distinctly narrower than 4; antennomere 11 about 2.7 times as long as wide, with distinct pattern of sensillae ( Fig. 3C ). Frontoclypeal suture straight anteriorly and with distinct anterolateral angles. Labrum weakly narrowed toward apex, apically emarginate. Mouthparts non-suctorial. Apical maxillary palpomere narrow and symmetrical, apically acute.

Prothorax widest at base. Lateral pronotal carinae complete, simple. Pronotal disc simple. Procoxae obliquely oriented, well-projecting, narrowly separated. Scutellar shield triangular, possibly with acute apex. Elytra about 1.8 times as long as combined width; transversely strigulate; sutural stria present; epipleuron narrow, incomplete. Hind wings present. 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 small; the smaller one not distinctly stouter than spines along apical fringe of mesotibia. Tarsi 5-5-5, simple. Meso- and metapretarsal claws with accessory lobes ( Fig. 3F ).

Abdomen with six ventrites. Aedeagus of trilobate type; penis shorter than parameres; parameres distinctly bowed outwardly.

Figures

FIGURE 1. General habitus of Eucinetus debilispinus Li & Cai sp. nov., holotype, NIGP203939, under incident light. A, Dorsal view. B, Ventral view. C, Lateral view. Scale bars: 500 μm.

FIGURE 2. General habitus of Eucinetus debilispinus Li & Cai sp. nov., holotype, NIGP203939, under confocal microscopy. A, Dorsal view. B, Ventral view. C, Lateral view. Scale bars: 500 μm.

FIGURE 3. Details of Eucinetus debilispinus Li & Cai sp. nov., holotype, NIGP203939, under confocal microscopy. A, Head, dorsal view. B, Head and prothorax, lateral view. C, Antennae. D, Meso- and metathorax, ventral view. E, Fore and mid legs. F, Hind legs. G, Scutellar shield, dorsal view. H, Elytral apex, dorsal view. I, Abdominal apex, dorsal view. Abbreviations: a1–11, antennomeres 1–11; lb, labrum; msem, mesepimeron; mstb, mesotibia; msts, mesotarsus; mtes, metanepisternum; mttb, metatibia; mtts, metatarsus; mxp, maxillary palp; pm, paramere; pts, protarsus; sc, scutellar shield. Scale bars: 100 μm.

FIGURE 4. X-ray microtomographic reconstruction of Eucinetus debilispinus Li & Cai sp. nov., holotype, NIGP203939. A, Dorsal view. B, Ventral view. C, Lateral view. Scale bar: 500 μm.