Omineus febribilis, Alekseev & Pollock & Bukejs, 2019

Alekseev, Vitalii I., Pollock, Darren A. & Bukejs, Andris, 2019, Two new fossil representatives of Eurypinae (Coleoptera: Tenebrionoidea: Mycteridae) from Eocene Baltic amber and placement of Neopolypria nigra Abdullah, 1964, Zootaxa 4551 (1), pp. 67-78 : 71-74

Omineus febribilis sp. nov.

( Figs. 6–10 )

Material examined. Holotype: No. AWI-142 [ CVIA], adult, female (protruding ovipositor; sex patches on ventrite 2 absent), almost complete specimen (left antennomeres 6–11 missing). The beetle inclusion is preserved in a small polished piece of transparent amber with a yellowish shade. The amber piece is embedded in a block of polyester resin (total measurements are: 14 × 8 × 4.5 mm). Syninclusions are absent.

Type strata. Baltic amber, Upper or mid-Eocene.

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

Diagnosis. The habitus of the new fossil species is similar to O. humeralis Lewis, 1895 and O. toyoshimai Young & Saitô, 2017 but differs from these species in having sparser and finer dorsal pubescence, distinctly longer antennae, intervals of elytra without definitive transverse rugosities, sparsely and finely punctate abdominal ventrites, shorter body length (3.8–5.4 mm in O. humeralis and 4.3–4.9 mm in O. toyoshimai ), metatarsomere 1 longer than metatarsomeres 2–4 combined, comparatively narrower frons, and unicolorous dark body and appendages.

Description. Body elongate, slightly convex dorsally, unicolorous dark brown. Elytral surface evenly covered with fine, decumbent pubescence. Pubescence of pronotum and head almost inconspicuous, very fine and short. Body length 3.1 mm; maximum body width 1.25 mm (elytra postmedially); pronotal length 0.50 mm; maximum pronotal width 0.75 mm; elytral length 2.33 mm.

Head. Slightly narrowed posterior of eyes. Eyes large, hemispherical, without intrafacetal setae, widely separated, anterior margin entire, with distinct facets equal in size to punctures on head. Clypeus flat, evenly depressed; frons convex. Minimum distance between eyes 1.2× as wide as longitudinal eye diameter measured laterally. Labrum distinctly transverse, with convex anterior margin. Mandibles apically bidentate. Terminal maxillary palpomere weakly securiform. Antennae 11-segmented, reaching base of pronotum. Antennomeres 1–6 oblong, filiform; antennomeres 7–10 conical, as wide as long; antennomere 11 longest, elongate, tapered.

Thorax. Pronotum transverse, distinctly narrower than width across elytral bases or head across eyes. Anterior pronotal margin arcuate, posterior margin straight; lateral margins slightly sinuate. Anterior angles obtuse, posterior angles almost rectangular. Lateral carina absent. Pronotal disc indistinctly convex, with four symmetrical transverse depressions: very shallow oblique pair slightly anterior of pronotal midlength, and deeper oval pair in posterior half of pronotum. Pronotal punctation rounded, coarse, dense. Intercoxal process not discernible (procoxae contiguous); procoxal cavities open.

Elytra elongate, with margins subparallel (slightly widened postmedially) and disc moderately convex. Humeri and elytral apices rounded. Dorsal surface evenly and irregularly punctate and setose. Setae decumbent, fine. Punctation shallow, dense, with distance between punctures equal to 0.5–1.5× diameter of one puncture. Scutellar shield transverse, oval. Mesocoxal cavities closed. Epipleura narrow, widest in basal part and then gradually narrowing posteriorly, extended to third ventrite. Metathoracic wings fully developed, distal areas partially exposed on specimen. Metaventrite convex, sparsely punctate medially. Discrimen extended anteriorly to near one third of metaventrite.

Legs slender. Procoxae conical, projecting, contiguous. Tibiae straight, subequal in length to femora. Tibial spurs short. Tarsal formula 5-5-4. Penultimate tarsomere lobed. Mesocoxae narrowly separated. Metatarsomere 1 longer than metatarsomeres 2–4 combined. Metatarsomere 1–4 length ratios equal to 19-5-3-5. Tarsal claws swollen basally, acute.

Abdomen. With five abdominal ventrites. Anterior process of ventrite 1 triangular. All ventrites finely, sparsely and shallowly punctate, setation inconspicuous, discernible sex patch(es) absent. Apex of terminal ventrite widely rounded. Distal parts of the reproductive system visible, making definite determination of female sex possible. Apical margin of ventrite 5 rounded. Ventrites 1–5 length (along midline) ratios equal to 1.8-1.8-1.7-1.0-1.3.

Etymology. The specific epithet of this new fossil species (Latin adjective «febribilis» means “feverish”, “calling of fever”) refers to the obsessive and passionate searching, mining, sampling, netting and collecting of amber in areas where it is endemic. This is called “Bernsteinfieber” (in German) or “febris succinica” (in Latin), i.e. amber “fever”.

Remarks. The dark, monochrome body color of the specimen could be a result of the fossilization in amber.

Figures

FIGURES 5–6. Reconstructions of Eurypinae from Baltic amber: 5—Glesoconomorphus nachzehrer gen. et sp. nov.; 6— Omineus febribilis sp. nov.

FIGURES 7–10. Omineus febribilis sp. nov., holotype, No. AWI-142 [CVIA]: 7—habitus, dorsolateral view; 8—habitus, ventrolateral view; 9—habitus, lateral view; 10—forebody, ventrolateral view.