Elasontagius dorbnickensis, Alekseev & Bukejs, 2020

Alekseev, Vitalii I. & Bukejs, Andris, 2020, A new genus of Hallomeninae Gistel, 1848 (Coleoptera: Ttenebrionoidae: Tetatomidae) from Eocene Baltic amber, Baltic Journal of Coleopterology 20 (2), pp. 189-195 : 191-194

Elasontagius dorbnickensis sp. nov.

( Figs. 1 –3)

Type material. Holotype: collection number 6702 [ MAIG] (ex. coll. Jonas Damzen JDC 8772) , Holotype / Elasontagius dorbnickensis gen. et sp. nov. / Alekseev et Bukejs des. 2020" [red printed label]; adult, sex unknown. A complete beetle included in a transparent, yellow amber piece with approximate dimensions of 35 mm × 23 mm and a maximum thickness of 10 mm; preserved without supplementary fixation. The ventral left part of the specimen is densely obscured by milky foam. Syninclusions (organic): few small stellate trichomes.

Type stratum. Baltic amber from Eocene amberbearing blue Earth layers, mostly Bartonian age is interpreted for the extinct central European resin-producing forests (Bukejs et al. 2019).

Type locality. Yantarny settlement (formerly Palmnicken), Sambian (Samland) Peninsula, Kaliningrad Region, Russia .

Description. Measurements: body length 3.6 mm, body maximum width 1.4 mm; pronotum length 0.6 mm, pronotum maximum width 1.4 mm; elytra length 2.9 mm, elytra maximum width 1.4 mm.

Body elongate, oval, slightly convex; total body length / maximum body width = 2.6; integument unicolorous brown (as preserved). Pubescence homogenous, strongly recumbent, fine and rather dense. Punctation irregular, fine and very dense.

Head slightly convex. Compound eyes large, entire, slightly convex, vertical, about 1.8× as height as long, with distinct facets, without interfacetal setation; interocular frontal distance about 1.5× vertical diameter of one eye. Frontoclypeal suture distinct, almost straight. Antennae filiform, 11-segmented, rather short, extending to basal 1/6 of elytra; scape elongate oval, about 3× as long as wide; pedicel as long as wide, smallest, 0.3× as long as scape; antennomeres 3–7 elongate, trapezoidal, slightly dilated apically; antennomeres 8–10 elongate oval, equal in length and shape, about 2× as long as wide; antennomere 11 spindle-shaped with pointed apex, about 3.2× as long as wide. Relative length ratios of antennomeres 1–11 equal to 15:5:6:7:7:7:8:10:10:10:16. Maxillary palps 4-segmented; palpomere 1 smallest (poorly visible in studied specimen), palpomeres 2–3 subequal in length and shape, elongate, about 1.8× as long as wide, triangular, with slightly oblique apex; palpomere 4 slightly dilated apically, obliquely truncate, about 1.2× as long as palpomere 3. Labial palps with small, narrowly elongate terminal palpomere.

Pronotum strongly transverse, 2.3× as wide as long, slightly convex dorsally, about 1.7× as wide as head including eyes; widest in basal 1/4, dis- wide as pronotum maximum width; lateral martinctly narrowed anteriad; basal pits or impres- gins subparallel in anterior 2/3 than gradually sions absent; posterior margin straight, lateral narrowed posteriad; elytral apices separately margins slightly convex and non-crenulate; an- rounded. Elytral punctation uniform, homogterior and posterior angles rounded. Prosternal enous, dense, fine; elytral disc without longituprocess narrow, distinctly narrower than diam- dinal impressions, striae or distinct rows of punceter of procoxa, longitudinally impressed. tures. Epipleura narrow, reaching posterior mar- Procoxal cavities open posteriorly. gin of abdominal ventrite 2.

Metepisternum long, reaching metacoxae,

subtriangular, widest anteriorly, entire. Scutellum Legs slender and rather long. Procoxae widely with widely rounded apex, strongly transverse, oval, about 1.3× as wide as long, narrowly sepa- 3.3× as wide as long. rated by procoxal process. Protrochantin not clearly visible. Metacoxae oval, strongly trans- Elytra elongate oval, slightly convex, 2.1× as long verse, contiguous. Femora spindle-shaped, flatas wide; about 4.8× as long as pronotum, and as tened. Tibiae simple, straight, narrower than femora; protibiae with fringe of stout, dark setae apically, without spines; meso- and metatibiae with two non-serrate spurs of equal length, spurs of metatibia about 0.3× as long as metatarsomere 1. Tarsi long, metatarsus about as long as metatibia; tarsal formula 5-5-4; tarsomeres of all legs cylindrical, simple (non-lobed). Relative length ratios of mesotarsomeres 1–4 equal to 7:6:4:8. Relative length ratios of metatarsomeres 1–4 equal to 17:11:6:9. Tarsal claws simple, long, equal in length, slightly swollen at base.

Abdomen with five visible ventrites; abdominal sutures entire, straight; ventrite 5 with slightly emarginate apical margin. Relative length ratios of abdominal ventrites 1–5 equal to 15-15-15-13- 10 (measured medially).

Note. Mesocoxae not visible in the studied specimen. Very fine and not complete sutural stria appears to be visible in apical half of elytra only.

Differential diagnosis. As for the genus (vide supra).

Derivatio nominis. The species name “dorbnickensis ” is toponymic and derived from the non-existent small East Prussian settlement Dorbnicken, on the ground of which the presentday amber mine “Primorskoe” is situated.

Note. The data on the presence of Hallomenus in European Eocene was not supported in present study. The newly described fossil strongly resembles this Holarctic genus, but the peculiar morphological character of the pronotum hinders Bouchard P., Bousquet Y., Davies A.E., Alonsous to place it in that recent genus. The feeding Zarazaga M.A., Lawrence J.F., Lyal C.H.C., Newassociation of this extinct Hallomenus-like bee- ton A.F., Reid C.A.M., Schmitt M., Ślipiński A. tle with any Polyporales and rotten wood is very 2011. Family-group names in Coleoptera ( Insecta). possible, but we cannot discuss the habitat con- ZooKeys 88: 1–972. nection with more confidence because the taxon is considered morphologically different from ex- Bukejs A., Alekseev V.I., Pollock D.A. 2019. tant relatives. Elasontagius dorbnickensis gen. Waidelotinae, a new subfamily of Pyrochroidae et sp. nov. is the second described member of ( Coleoptera : Tenebrionoidea) from Baltic amber Tetratomidae from Eocene Baltic amber. of the Sambian peninsula and the interpretation of Sambian amber stratigraphy, age and location.

Zootaxa 4664 (2): 261–273.

ACKNOWLEDGEMENTS

Cai C., Hsiao Y., Huang D. 2016. A new genus and

The authors are sincerely grateful to Dr. Elżbieta species of polypore fungus beetle in Upper Cre- Sontag (Museum of Amber Inclusions, Univer- taceous Burmese amber ( Coleoptera , sity of Gdańsk, Poland) for the loan of interest- Tetratomidae , Eustrophinae ). Cretaceous Reing fossil specimen, and to Mr. Jonas Damzen search 60: 275–280. (Vilnius, Lithuania) for assistance during our amber research and permission to use photo- Hsiao Y., Ślipiński A., Yu Y., Deng C., Pang H. graphs. We thank Dr. Marcin Jan Kamiński (Mu- 2018. Allostrophus cretaceus gen. et sp. nov.: a seum and Institute of Zoology, Polish Academy new polypore fungus beetle ( Coleoptera , of Sciences, Warszawa, Poland) and one anony- Tetratomidae ) from the Cretaceous Myanmar mous reviewer for their helpful comments and amber. Cretaceous Research 92: 195–200. corrections to an earlier version of this manuscript. The study of VIA was done with the sup- Kaszab Z. 1969. Familie: Serropalpidae port of the state assignment of IO RAS (Theme ( Melandryidae ). In: Freude, H., Harde, K.W. & No.0149–2019–0013). Lohse, G.A. (eds.), Die Käfer Mitteleuropas.

Band 8, Goecke & Evers, Krefeld, 196–213.