Glesoconomorphus nachzehrer, 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 : 69-71

Glesoconomorphus nachzehrer sp. nov.

( Figs. 1–5 )

Material examined. Holotype: No. 478-2 [ CCHH], adult, sex unknown, almost complete (right metatibia and metatarsus, distal part of right protibia and protarsus, and left mesotarsus partially missing). The beetle inclusion is preserved in a polished piece of transparent amber with a yellowish shade. The small amber piece is embedded in a block of polyester resin (total measurements are: 18 × 10 × 5 mm). Syninclusions are represented by numerous pollen grains.

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

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

Diagnosis. As stated above, for the new genus.

Description. Body elongate, slightly convex dorsally, dark brown, unicolorous. Dorsal surface evenly covered with fine, decumbent, conspicuous pubescence. Body length 3.6 mm; maximum body width 1.25 mm (elytra postmedially); pronotal length 0.68 mm; maximum pronotal width 0.68 mm; elytral length 2.65 mm.

Head. Moderately narrowed posterior of eyes. Eyes protruding, hemispherical, without intrafacetal setae, widely separated, with entire and straight anterior margin, with distinct facets (as large as punctures on head). Frons convex, minimum distance between eyes 1.5× as wide as longitudinal eye diameter measured laterally. Ocular (suborbital) grooves present, narrowly separated from eyes, distinct, fine, traceable from frontal canthus to posterior extent of eye. Labrum with anterior margin convex. Terminal maxillary palpomere broadly triangular. Antennae 11-segmented, relatively short, reaching posteriorly to near basal third of pronotum. Antennomeres 1–6 cylindrical, longer than wide; antennomeres 7–10 subtriangular; antennomere 11 egg-shaped, longest, about 1.5× as long as antennomere 10.

Thorax. Pronotum subquadrate, widest at midlength. Pronotal base distinctly narrower than elytral base or maximum width of head across eyes. Anterior and lateral margins of pronotum slightly rounded, posterior margin slightly sinuate. Lateral carina absent. Anterior angles broadly rounded, not produced; posterior corners rightangled. Pronotal disc slightly convex, with pair of oblique symmetrical depressions. Posterior margin with distinct, deep, transverse groove. Prosternum long anterior of procoxae. Intercoxal process extended to one-half length of procoxae (procoxae contiguous); procoxal cavities appear to be posteriorly open.

Elytra elongate, disc moderately convex; dorsal surface evenly and irregularly punctate and setose, punctation slightly denser basally on elytra. Setae decumbent, long (equal to 1.5–2.0× distance between punctures); distance between punctures equal to 1.0–2.0× diameter of one puncture. Punctation sparser towards apices. Scutellar shield transverse, pentagonal, rounded. Mesocoxal cavities closed. Elytral epipleura narrow, widest in basal part and then gradually narrowing posteriorly, extended to first ventrite. Metaventrite convex, medially smooth, with very fine and sparse punctation. Discrimen extended anteriorly to near middle of metaventrite.

Legs slender. Procoxae subconical, contiguous. Meso- and metacoxae narrowly separated. Tibiae straight, subequal in length to femora. Tibial spurs short. Tarsal formula 5-5-4. Penultimate tarsomere distinctly widened distally. Tarsal claws strongly appendiculate, with large basal tooth. Metatarsomere 1–4 length ratios equal to 15-7- 3-7.

Abdomen. With five abdominal ventrites. Anterior process of ventrite 1 triangular, pointed. All ventrites punctate, setose, without discernible sex patch(es). Punctation of ventrites 1–2 sparser (1.5–2.0× diameter of one puncture), punctation of ventrites 3–5 denser and coarser (0.3–1.0× diameter of one puncture), almost rugose. Apical margin of ventrite 5 rounded. Ventrite 1–5 length (along midline) ratios equal to 2.1-1.8-1.8-1.3-1.0.

Etymology. The specific epithet is a German word used as a noun in apposition. A “Nachzehrer” is a sort of undead, or vampire from the folklore of the northern regions of Germany and Poland (Kashubia). According to legend, upon waking, a Nachzehrer first persecutes and murders his natural relatives. The name of this new species refers to the remarkably well-preserved state of the amber inclusions [“ever-living appearance”], the absence of mycterids in present-day Europe [“mysteriously extirpated by something”] and also a reference to the southern Baltic Sea region [including historical Kashubian area].

Remarks. Due to imperfections and cracks in the amber, the procoxae and mouthparts were impossible to examine. Also, the genitalia and metathoracic wings remained internal and were not extended in the specimen. The dark, monochrome body color of the specimen could be a result of the fossilization in amber, and not represent its actual color in life.

Figures

FIGURES 1–4. Glesoconomorphus nachzehrer gen. et sp. nov., holotype, No 478-2 [CCHH]: 1—forebody, dorsal view; 2— forebody, ventrolateral view; 3—habitus, dorsal view; 4—habitus, ventrolateral view.

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