Baltistena longistrigata, 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 : 462-468

Baltistena longistrigata sp. nov.

( Figs 7A–D )

Type material. HOLOTYPE: PřfUK69, obtained from rmvveta (www. ambertreasure4u.com) (original number 293822360959): Baltic amber.

Description. Head subglobular, frons continuously convex, posterior edge of eye near posterior margin of head, elytra convex, metacoxae expanded, comb formula 1+2//3/1/0/0, pygidium long. Male genitalia partly extruded. Main characters: Form of antennae: five or six basal antennomeres visible, cylindrical, about 2× as long as wide. Structure of maxillary palpi indiscernible. Eyes rounded, with about 20 facets across middle of eye. Interfacetal setae absent. Form of scutellum indiscernible. Form of basal side of pronotum indiscernible. Elytra 4× as long as pronotal disc. Form of protarsomeres indiscernible. Protibia straight and robust. Mesotarsomere IV shortest, oblique at apex, deeply dilated. Length ratio of mesotibia and respective tarsus unknown. Type of combs on metatibia: preapical comb shortest, two subsequent combs about 2× as long as preapical one, straight, formed by shorter and finer setae. Presence or absence of outer tibial spurs on metatibia indiscernible. Type of combs on metatarsus: metatarsomere I with three short transverse combs, metatarsomere II with one short comb formed by four scale-like setae situated close to posterior edge of tarsomere. Pygidium 3.3× as long as hypopygium.Anterior edge of metanepisternum 1.7× as long as its posterior edge, ventral edge 4.5× as long as its posterior edge. Metakatepisternum absent. Pretarsal claws without visible teeth. Tip of pygidium with setae similar to those on rest of pygidium.

Lengths (in mm): pronotal disc = 0.8, elytra = 2.4, mesotibia = 2.0, metatarsomere I = 0.5, pygidium = 1.35. Etymology. The species name refers to the remarkably long lateral combs on metatibia; adjective.

Differential diagnosis. Among Eocene Mordellistenini this species is unique in terms of its long and strongly oblique tibial combs (excluding preapical one). Among the extant genera with penultimate pro- and mesotarsomeres emarginated or bilobed and similar long and oblique metatibial combs are the monotypic African Fahraeusiella Ermisch, 1953 , worldwide distributed Glipostenoda Ermisch, 1950 , Mordellistenoda Ermisch, 1941 from the Oriental and Australian Realm, Morphomordellochroa Ermisch, 1969 with two African species, and Xanthomorda Ermisch, 1969 from Africa and Papua New Guinea. However, the comb formula and shape and length of the combs of Baltistena longistrigata sp. nov. are different from species of the above-mentioned genera depicted in ERMISCH (1941b, 1950b, 1953, 1969), FRANCISCOLO (1958) and SHIYAKE (1997). For more affinities and differences from the above-mentioned genera the obscured mouthparts and antennae of the holotype (if preserved) have to be investigated using microtomography.

Figures

Figs 7. A–I – Mordellistenini, Baltic amber. A–D – Baltistena longistrigata sp. nov., holotype, PřFUK69: A – habitus; B – hypopygium; C – hind leg; D – head and pronotum laterally. E–I – Baltistena hoffeinsorum sp. nov., holotype, PřFUK92: E – habitus; F – hind legs; G – metatarsomere IV and serrate pretarsal claws; H – hypopygium; I – eye. Scale bars: A, F – 0.5 mm; B – 0.15 mm; C, D, H – 0.2 mm; E – 0.8 mm; G – 0.05 mm; I – 0.3 mm.