Baltistena atronigra, Batelka & Rosová & Prokop, 2023

Batelka, Jan, Rosová, Kateřina & Prokop, Jakub, 2023, Diversity and morphology of Eocene and Oligocene Mordellidae (Coleoptera), Acta Entomologica Musei Nationalis Pragae 63 (2), pp. 451-478 : 469-472

Baltistena atronigra sp. nov.

( Figs 9G–K , 10F )

Type material. HOLOTYPE: PřfUK108, obtained from ‘vermiculosis’ – Poland: Baltic amber.

Description. Head subglobular, frons continuously convex, posterior edge of eye near posterior margin of head, elytra convex, metacoxae broad, comb formula 5//5/?/?/?, pygidium long. Main characters: Only right antenna almost complete, but poorly visible because of distortion; four basal antennomeres short and cylindrical; antennomere V as long as preceding two, with distal edge distinctly wider; antennomere IX almost cylindrical with apex slightly wider, antennomeres X and XI cylindrical. Maxillary palpomere IV small, malleiform (bean-shaped). Facetes moderatelly sized. Long interfacetal setae present. Form of scutellum indiscernible (dorsal view not available). Basal side of pronotum indiscernible (dorsal view not available), posterior angles of pronotal disc obtuse. Elytra about 3.5× as long as pronotal disc. Protarsomeres cylindrical, straight, length ratios not measurable. Shape of protibia not discernible. Mesotarsomere IV cylindrical, straight. Mesotibia as long as respective tarsus. Metatibia with five long transverse combs. Two subequal tibial spurs inserted on metatibia, but their length not measurable. Metatarsomere I with five long transverse combs, metatarsomeres II with two short combs, tarsomeres III–IV poorly visible. Pygidium 2.5× as long as hypopygium. Metanepisternum partly hidden behind middle leg. Metakatepisternum fully developed, suture between metakatepisternum and metaventrite straight, metacoxal margin distinctly concave ventrally. Pretarsal claws with distinct sharp long teeth. Tip of pygidium with setae similar to those on rest of pygidium.

Lengths (in mm): pronotal disc = 0.85, elytra = 3.0, mesotibia = 0.9, metatarsomere I = 0.6, pygidium = 1.3.

Etymology. The species name refers to the dull black colour of the body; adjective.

Differential diagnosis. This species is characterized by truncated pro- and mesotarsomere IV, antennomeres I–IV combined shorter than antennomeres V–VII combined, antennomere IV cylindrical, half the length of antennomere V, antennomere V robust, distinctly broader apically, maxillary palpomere IV small malleiform (bean-shaped), eyes with large facets with long interfacetal setae, posterior angles of pronotal disc obtuse, suture between metakatepisternum and metaventrite straight, metacoxal margin distinctly concave ventrally, combs short and transverse, complete comb formula indiscernible. For its features differing from the 12 extant genera and subgenera with truncated pro- and mesotarsomere IV see Table 2.

Figures

Figs 9. A–K – Mordellistenini, Baltic amber.A–F – Baltistena brevispina sp. nov., holotype, PřFUK95: A – habitus; B – hind leg; C – eye; D – hypopygium; E – middle leg; F – fore leg. G–K – Baltistena atronigra sp. nov., holotype, PřFUK108: G – habitus; H – eye; I – hind legs; J – hypopygium; K – base of pronotal disc and scutellum. Scale bars: A – 1.0 mm; B – 0.4 mm; C, J – 0.3 mm; D, I – 0.5 mm; E, F – 0.15 mm; G – 0.8 mm; H, K – 0.2 mm.

Figs 10. A–F – Metakatepisternum: A – Baltimorda, undescribed species A, PřfUK71. B – Palaeostena eocenica (Kubisz, 2003), PřfUK107. C – Baltistena hoffeinsorum sp. nov., holotype, PřFUK92. D – Baltistena concava sp. nov., holotype, PřFUK93. E – Baltistena brevispina sp. nov., holotype, PřFUK95. F – Baltistena atronigra sp. nov., holotype, PřFUK108. Scale bars: 0.2 mm.