Baltistena brevispina, 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

Baltistena brevispina sp. nov.

( Figs 9A–F , 10E )

Type material. HOLOTYPE: PřfUK95, obtained from Jonas Damzen (original number JDC4109 ): Baltic amber.

Description. Head subglobular, frons continuously convex, posterior edge of eye near posterior margin of head, elytra convex, metacoxa broad, comb formula 7//6/2/0/0, pygidium long. Main characters: Both antennae almost completely visible, length ratios of antennomeres: 2-1.3- 1-1.3-2-1.6-1.3-1.6-1.6-1.6-2.3, basal antennomere robust, flagellomeres cylindrical with both margins almost parallel. Structure of maxillary palpi indiscernible. Eyes with small facets. 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 sharply pointed. Elytra about 3.7× as long as pronotal disc. All protarsomeres cylindrical, straight, length ratios: 4-3-1.8-1.4-1.5. Protibia seemingly shallowly curved in lateral view. Mesotarsomere IV straight. Mesotibia longer than respective tarsus. Metatibia with seven short transverse combs. Two subequal tibial spurs on metatibia, outer one half as long as inner one. Metatarsomere I with six short transverse combs, metatarsomere II with two short combs, tarsomeres III and IV without combs. Pygidium 2.2× as long as hypopygium. Anterior edge of metanepisternum 1.6× as long as its posterior edge, ventral edge 3.0× as long as posterior edge. Metakatepisternum fully developed, suture between metakatepisternum and metaventrite almost parallel with metacoxal margin. Pretarsal claws with two or three widely spaced teeth. Tip of pygidium with very short black scale-like setae.

Lengths in mm: pronotal disc = 1.2, elytra = 3.3, mesotibia = 1.1, metatarsomere I = 0.75, pygidium = 1.7.

Etymology. The species name refers to the short spiniform setae on the ventral edge of metatibia.

Differential diagnosis. This species is characterized by truncated pro- and mesotarsomere IV, antennomeres I–IV combined shorter than antennomeres V–VII combined, antennomere IV shorter than antennomere V, eyes small with small facets, posterior angles of pronotal disc sharp and suture between metakatepisternum and metaventrite almost parallel with metacoxal margin. Characters of Baltistena brevispina sp. nov., including the shape of antennomeres, with some reservations fit the definition of the genus Mordellistena (s. str.), particularly the M. pumila or M. pentas species-group. ERMISCH (1963: 16) defines the M. pumila species-group as follows: antennomere IV shorter than antennomere V, metatibia with 3–4 short combs, metatarsomere I with 2–5 short combs, metatarsomere II with only two similar combs (unlike the M. pentas species-group where three combs are present on metatarsomere II). In Baltistena brevispina sp. nov. the number of combs is, however, slightly different (see description above).

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.