Burmalestes jingruoyaae Li & Cai, 2023

Li, Yan-Da, Huang, Di-Ying & Cai, Chen-Yang, 2023, A new species of Burmalestes Tomaszewska & Ślipiński from mid-Cretaceous Kachin amber (Coleoptera: Endomychidae), Zootaxa 5396 (1), pp. 105-111 : 106-108

Burmalestes jingruoyaae Li & Cai sp. nov.

( Figs 1–4 )

Material. Holotype, NIGP203386 .

Etymology. The specific name is dedicated to Ms. Ruoya Jing, aiming to inspire her interest in fossil insects and nature in general.

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. Burmalestes jingruoyaae sp. nov. differs from B. albertalleni Tomaszewska & Ślipiński primarily in the absence of sulci on the pronotal disc ( Fig. 4F ). The abdomen with six visible sternites ( Fig. 4C ) (also seen in several Cretaparamecus specimens; Arriaga-Varela et al., 2023) might be a potential differential character (five in the holotype of B. albertalleni ), although it might not necessarily be a natural state (like the outstretched genitalia seen in other amber fossils; e. g., Li et al., 2022b, 2022c). The tooth on the inner edge of protibia ( Fig. 4G ) is also a potential differential character (absent in the holotype of B. albertalleni ), although it could be only a sexually dimorphic character as well.

Description. Body elongate-oval, about 1.5 mm long (including the protruding abdominal apex), 0.5 mm wide; surface with scattered short hairs.

Head prognathous, not abruptly constricted behind eyes. Eyes moderately protuberant, coarsely facetted; interfacetal setae absent. Antennal insertions widely separated, dorsally concealed. Antennae 11-segmented; antennomeres 1 and 2 elongate; antennomeres 3 and 4 moniliform; antennomere 5 elongate and widened; antennomeres 6–8 moniliform, with antennomere 7 slightly larger than adjacent ones; antennomeres 9–11 forming loose and indistinct club. Mandibles apically bidentate. Apical maxillary palpomere subconical; galea with dense apical setae. Labial palp 3-segmented; apical palpomere subcylindrical, distinctly longer than palpomere 2.

Pronotal disc about 0.8 times as long as wide; widest near anterior 1/4, slightly constricted near basal 1/3; lateral edges sinuate; anterior and posterior edges almost straight; anterior angles broadly rounded; posterior angles nearly right-angled; surface flat, without any clear impressions. Procoxae subcontiguous (or contiguous).

Elytra about 1.5 times as long as width combined, finely and irregularly punctate; epipleuron incomplete apically. Mesocoxae narrowly separated. Metaventrite without clear postcoxal pits. Metacoxae broadly separated.

Legs elongate. Protibiae subapically with large tooth on inner edge; tibial spurs absent. Tarsi 4-4-4; protarsus with tarsomeres 1–2 thickened; meso- and metatarsi slender. Pretarsal claws simple.

Abdomen with six freely articulated sternites visible. Ventrite 1 almost as long as ventrites 2–5 combined, without postcoxal lines; intercoxal process broadly truncate. Ventrites 2–4 subequal in length. Ventrite 5 apically broadly rounded. Sternite VIII with apex emarginate.

Figures

FIGURE 1. General habitus of Burmalestes jingruoyaae Li & Cai sp. nov., holotype, NIGP203386, under incident light. A, Dorsal view. B, Ventral view. Scale bars = 500 μm.

FIGURE 2. General habitus of Burmalestes jingruoyaae Li &Cai sp. nov., holotype,NIGP203386, underwidefield fluorescence. A, Dorsal view. B, Ventral view. Scale bars = 500 μm.

FIGURE 3. General habitus of Burmalestes jingruoyaae Li & Cai sp. nov., holotype, NIGP203386, under confocal microscopy. A, Dorsal view. B, Ventral view. Scale bars = 500 μm.

FIGURE 4. Details of Burmalestes jingruoyaae Li & Cai sp. nov., holotype, NIGP203386, under confocal microscopy. A, Head, ventral view. B, Pro- and mesothorax, ventral view. C, Abdominal apex, ventral view. D, Antenna, ventral view. E, Head, dorsal view. F, Prothorax, dorsal view. G, Fore leg. H, Mid leg. I, Hind leg. Abbreviations: a1–5, antennomeres 1–5; gl, galea; lbp, labial palp; md, mandible; msc, mesocoxa; msf, mesofemur; mstb, mesotibia; mstc, mesotrochanter; msts, mesotarsus; mttb, metatibia; mtts, metatarsus; mxp, maxillary palp; pc, procoxa; pf, profemur; ps, prosternum; ptb, protibia; pts, protarsus; v1–5, ventrites 1–5. Scale bars = 100 μm.