Dieneremia rueckeri, Reike, Hans-Peter, Alekseev, Vitaly I. & Bukejs, Andris, 2013

Reike, Hans-Peter, Alekseev, Vitaly I. & Bukejs, Andris, 2013, Dieneremia rueckeri, a new genus and species of minute brown scavenger beetle from Baltic amber, with notes on other fossil Latridiidae (Coleoptera: Cucujoidea), Zootaxa 3686 (3), pp. 381-388 : 383-385

Dieneremia rueckeri sp. nov.

( Figs. 1–5 )

Material examined. Holotype: Nr. AWI-008, sex unknown; deposited in the private collection of V.I. Alekseev (Kaliningrad, Russia). The type will be deposited in the Paleontological Institute, Russian Academy of Science (Moscow) for permanent preservation. The beetle is included in a small and thin subquadrate amber piece 20 mm x 15 mm (L:W). Prior to examination, the amber piece was subjected to thermal and high-pressure processing in an autoclave.

Type strata. Baltic Amber, Upper Eocene, Prussian Formation.

Type locality. Baltic Sea coast, Yantarny village [formerly Palmnicken], Kaliningrad Region, Russia.

Etymology. The epithet of this new species is devoted to our dear friend and colleague, Wolfgang H. Rücker (Neuwied, Germany), acknowledged specialist on the Latridiidae and Merophysiinae (Endomychidae) .

Description. Body length: 1.7 mm; max. width: 0.55 mm. Elongate, somewhat flattened; dorsal surface brown, glabrous.

Head dorsally covered with dense and large punctation and coarse rugosity; approximately as long as wide; head together with eyes approximately as wide as the pronotum at its widest part. Frons with four distinct longitudinal carinae, outer carinae apically toothed. Head in basal part with deep, wide impression. Mandibles not visible, dorsally obscured by the labrum. Labrum transverse, anterior margin widely rounded. Clypeus with straight anterior and posterior margins. Mentum relatively large, approximately as wide as the scape length; subtrapezoidal, with emarginated anterior margin. Eyes large, strongly convex, with distinct facets; interocular distance 3.5 times as long as width of eye. Temples parallel, with right angles posteriorly, pointed, very large, approximately half of eye width. Antennae 11-segmented, moderately long, reaching basal 1/3 of pronotum. Scape large, subtriangular, strongly widened distally, inner anterior angle pointed and possessing a sharp spine. Pedicel elongate, more slender, 0.5 times as long as scape but longer than antennomere 3, inserted into scape asymmetrically (insertion located lateroapically). Antennomeres 3–8 elongate, subequal, slightly widened distally. Antennal club 3-segmented, relatively loose; antennomere 11 large, as long as pedicel, oval; antennomere 9 widened distally, approximately half as long as 11; antennomere 10 shorter than 9, approximately as long as wide. Distance between antennal insertions large, approximately as long as scape.

Pronotum cordiform, widest in anterior 1/3, approximately as long as wide, slightly narrowed anteriorly, strongly narrowed posteriorly; lateral margins weakly crenulate, rounded in anterior half, subparallel in basal 1/3; posterior margin straight, 0.59 times as wide as base of elytra; anterior angles prominent and rounded, posterior angles obtuse and pointed. Posterolateral impression near the posterior angles round, distinct, connected by an impression, interrupted medially by two subparallel carinae. Dorsal surface of disk with two longitudinal carinae transected by three pairs of transverse carinae, bounding two deep impressions on each side as well as one large impression in the central anterior third. Punctation indistinct but visible in the anterior pronotum, similar in size and density to that of head. Hypomera broad, flattened.

Scutellum about twice as wide as long. Elytra oblong, subparallel, about 1.9 times as long as wide, with maximal width approximately at midlength; humeri strongly prominent anteriorly with sharp carinae. Each elytron with three longitudinal carinae interspaced by double striae of coarse punctures. Elytral punctures large, dense; distance between striae distinctly smaller than diameter of punctures (exact number of striae not discernible due to opacity of the amber, especially near elytral apex). Lateral margins of elytra broadly flattened.

Ventral side indistinctly visible ( Fig. 2 ), partly covered with secretion (remains of this secretion visible medially on ventral side of head, anterior part of prosternal process, around mesocoxae, ventrad to metacoxae, and at the base of each abdominal ventrite). Basal part of the head and anterior pronotum with dense and large punctation, coarse rugosity. Procoxae nearly round, cone-shaped, separated by relatively wide prosternal process (only slightly narrower than procoxal diameter), distinctly raised relative to prosternal process; meso- and metacoxae transverse, oval. Posterior to mesocoxae with fine, nearly parallel grooves (where secretion appears to originate similar to recent members of Cartodere , Enicmus or Latridius ) that reach the metacoxa. Central part of these grooves with a larger, coarsely punctured, longitudinal impression. Similar grooves located anterior to mesocoxae as well as on abdominal ventrite 1. Abdomen with five ventrites; ventrite 1 longest, approximately 1.5 times longer than 2; ventrite 2 longer than 3; ventrites 3 and 4 subequal; ventrite 5 shorter. Metaventrite separated from the first abdominal ventrite by metacoxae.

Legs moderately long and narrow. Trochanters long, slender, obliquely attached to femur. Femora spindleshaped, thickest at middle and 1.5–2.5 times as wide as tibiae. Tibiae slender; tibiae and femora subequal in length. Tarsomeres 1 and 2 subequal; tarsomere 3 markedly (2.2 times) longer than the preceding segments combined. Claws simple, small, thin.

Figures

FIGURES 1 – 3. Dieneremia rueckeri gen. et sp. nov., holotype. 1, dorsal habitus; 2, ventral habitus; 3, closeup of head and prothorax, dorsal view.

FIGURES 4 – 5. Dieneremia rueckeri gen. et sp. nov., holotype. 4, dorsal habitus; 5, ventral habitus.