Baltocar sontagae, Bukejs & Legalov, 2021

Bukejs, Andris & Legalov, Andrei A., 2021, Two new species of the family Rhynchitidae (Coleoptera: Curculionoidea) from Eocene Baltic amber, with key to species and assumed trophic relationships, Fossil Record 24 (1), pp. 117-127 : 118-120

Baltocar sontagae sp. nov.

urn:lsid:zoobank.org:act:1B0A90AB-068E-4D98-976E-291FC55B410A

Figs. 1–2 .

Etymology

Patronymic. This new species is named in honour of our colleague Elżbieta Sontag (Gdańsk, Poland), who provided us the opportunity to study this interesting fossil specimen.

Type material

Holotype. Collection number “6703” ( MAIG) (ex. coll. Jonas Damzen JDC 9012), “ Holotype / Baltocar / sontagae sp. nov. /Bukejs et Legalov des. 2021” (red printed label); adult, sex apparently female. A complete beetle included in a transparent, yellow amber piece with approximate dimensions of 24 mm × 5 mm and a maximum thickness of 4 mm, preserved without supplementary fixation. The right part of the specimen is partially obscured by milky amber. Syninclusions: one Brachycera (Diptera) specimen.

Type stratum

A predominantly Bartonian age (41.3–37.9 Ma) is interpreted for the extinct central European resin-producing forests, which produced the amber that has eroded out of Eocene Blue Earth layers (Bukejs et al., 2019). However, the vast majority of Baltic amber derives from the geological amber-bearing strata of the certainly Priabonian age (37.8– 33.9 Ma) ( Sadowski et al., 2017, 2020).

Type locality

Baltic Sea coast, Yantarny settlement (formerly Palmnicken), Sambia (Samland) Peninsula, Kaliningrad Region, Russia.

Description

Measurements. Body length (without rostrum) about 2.4 mm, body maximum width 1.1 mm; rostrum length 0.82 mm, rostrum width basally 0.16 mm, medially 0.12 mm, apically 0.20 mm; pronotum length 0.7 mm, pronotum maximum width 0.6 mm; elytra length 1.7 mm, elytra maximum combined width 1.1 mm.

Body. Unicolourous black (as preserved). Pubescence: pronotum with sparse, short, semierect thin setae; elytra with sparse, short, recumbent to slightly semierect setae; and ventral side of body with sparse, fine, recumbent setae.

Head. Forehead flat, with middle furrow; vertex convex, covered with sparse and fine punctation; temples 0.6× as long as horizontal diameter of one eye, with sparse and fine punctation. Rostrum rather long, 1.1 times as long as pronotum, slightly curved (in lateral view), widened apically (in dorsal view), about 5.1× as long as wide basally, 6.8× as long as wide medially, and 4.1× as long as wide apically; covered with very fine and sparse punctures. Compound eyes large, oval, strongly convex, vertical diameter about 0.7× as horizontal diameter. Maxillary palpi with four palpomeres.

Antennae. With 11 antennomeres, not geniculate, with distinct three-antennomered club; moderately long, about 1.2× as long as rostrum, reaching elytral posterior margin, inserted at base of rostrum; scape cylindrical, 2.4× as long as wide, and almost as long as antennomere 2; antennomere 2 subcylindrical, about 2.2× as long as wide, as wide as scape and 1.7× as wide as antennomere 3; antennomeres 3–6 subconi-

A. Bukejs and A. A. Legalov: Two new species of the family Rhynchitidae ( Coleoptera : Curculionoidea ) 119

cal, elongate, 3.3× as long as wide, equal in size and shape; antennomere 7 conical, about 2.7× as long as wide, slightly shorter than antennomere 6; antennomere 8 shortest, 2× as long as wide; antennal club (antennomeres 9–11) about 0.5× as long as flagellum (antennomeres 2–8); antennomere 9 about 1.1× as long as wide, dilated apically, about 2.2× as wide as antennomere 8; antennomere 10 about 1.1× as long as wide, slightly wider than antennomere 9, slightly dilated apically; antennomere 11 spindle-shaped with pointed apex, 1.6× as long as wide; relative length ratios of antennomeres 1–11 equal to 12: 11: 10: 10: 10: 10: 8: 6: 8: 9: 13.

Pronotum. Bell-shaped, elongate, 1.6× as long as wide at apex, 1.4× as long as wide in middle and at base, widest in posterior one-fifth, gradually narrowed anteriad; moderately densely covered with small punctuation; irregularly rugose; disc flat; lateral margins straight, posterior margin distinctly convex, anterior margin convex in dorsal view.

120 A. Bukejs and A. A. Legalov: Two new species of the family Rhynchitidae ( Coleoptera : Curculionoidea )

Figures

Figure 1. Photomicrographs of Baltocar sontagae sp. nov., holotype, 6703 (MAIG): (a) habitus, left lateral view; (b) details of forebody, lateral view. Scale bars = 0.25 mm. Abbreviations: a1–a11 denote antennomeres 1–11.

Figure 2. X-ray micro-CT renderings of Baltocar sontagae sp. nov., holotype, 6703 (MAIG), habitus: (a) dorsal view; (b) dorso-frontal view; (c) left lateral view. Scale bar = 0.5 mm.