Xylolaemus richardklebsi

Alekseev, Vitalii I. & Bukejs, Andris, 2016, New Zopheridae (Coleoptera: Tenebrionoidea) from Baltic amber, Zootaxa 4178 (3), pp. 409-427 : 412-413

X. richardklebsi Alekseev & Bukejs sp. nov.

( Figs 4–6 , 23 )

Type material. Holotype: Nr. 138-3 [CCHH] “Holotype / Xylolaemus richardklebsi sp. nov. / des. Alekseev V.I. & Bukejs A.” [red hand-written label]; sex unknown. Complete beetle with partially exposed hind wings and distal portion of genitalia visible, included in small, transparent yellow amber piece embedded in GTS-polyester resin block with dimensions 15 × 7 × 6 mm. Syninclusions (except one gas bubble) are absent—amber piece with inclusion may have been thermally processed in autoclave.

Type strata. Baltic amber, Upper Eocene , Prussian Formation (Priabonian). Estimated age: 37.2–33.9 Ma.

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

Differential diagnosis. Xylolaemus richardklebsi sp. nov. differs from extant and fossil species of the genus in the following combination of characters: pronotum with longitudinal impression medially; setae on elytra long and strongly curved; pronotal granulation dense; prosternal process dilated; fascicules (setose patches) on elytra absent; antennae 11-segmented with antennomere 10 dilated and transverse.

Description. Body length about 4.1 mm, maximal width 1.4 mm; elongate, nearly parallel-sided, flattened dorsally; body and appendages appear uniformly black.

Head. Longer than wide; widest between antennae; covered with moderately large, round, unisetose granules. Anterior clypeal margin straight, covered with thin setae. Lateral margins convex above antennal insertions and narrowing to anterior margin. Eyes large, prominent, hemispherical, with coarse facets; interfacetal setae apparent. Maxillary palpus 4-segmented, short; palpomere 4 oval-shaped, slightly longer and narrower than palpomere 3. Labial palpus 3-segmented, palpomere 3 oval, as long as penultimate palpomere. Antennae short, extending to basal half of pronotum; 11-segmented with distinct, 2-segmented, finely pubescent antennal club, sparsely covered with dark, semierect setae. Scape, pedicel and antennomeres 3–4 elongate, conical; antennomeres 5–9 transverse; antennomere 10 transverse, dilated distally, 0.7× as long as wide; antennomere 11 widely ovate with rounded apex, slightly longer than wide.

Thorax. Pronotum transverse, 1.3× as wide as long, widest at middle; pronotal disc convex with longitudinal impression at middle, lateral sides explanate; densely covered with unisetose granules (slightly smaller and distinctly denser than granules on frons). Anterior margin arcuate; lateral margins nearly parallel-sided, finely denticulate (about 12 small denticles), with each denticle bearing short seta; posterior margin rounded; anterior angles triangular, acute, prominent, reaching posterior half of eye; posterior angles obtuse. Prosternum densely covered with granules (sparser than pronotal granulation); procoxa nearly round, shagreened. Granules of meso- and metasternum flatter than those of prosternum. Procoxal cavities externally open, meso- and metacoxal cavities closed; all coxae narrowly separated from each other. Prosternal process oblong parallel-sided between procoxae and then strongly dilated,with widely rounded apex.

Scutellum small, rounded. Elytra elongate (length 2.7 mm, maximum width 1.4 mm), nearly parallel-sided, flattened dorsally, slightly wider than pronotum, jointly rounded apically. Humeral angles rounded. Each elytron with 10 rows of small, round punctures, distance between strial punctures equal to diameter of one puncture; intervals flat, distance between striae approximately 1.5–2.0× diameter of single puncture. Striae with small regular tubercles, bearing long, strongly curved setae. Scutellary striole apparent, consisting of four punctures. Epipleura well-developed, reaching apex of elytra, widest at humeral angle. Hind wings apparent. Ratio of lengths of mesoventrite to metaventrite to abdomen: 3-5-14.

Abdomen. With five visible, similarly articulated ventrites. Ventrite length ratios: 6-4-5-3-3. Setation of ventrites 1–4 not apparent (possibly absent); ventrite 5 rounded apically, finely pubescent, with two long, erect setae near apical margin, length of setae approximately 0.14 mm. Intercoxal process of abdominal ventrite 1 acute.

Legs. Profemora thickened medially; tibiae covered with curved setae. Tarsi tetramerous. Metatarsomere 4 as long as metatarsomeres 1–3 combined; pro- and mesotarsomeres 4 slightly shorter than combined length of tarsomeres 1–3. Tarsal claws simple, large, equal in size, with length about one-third of tarsomere 4.

Etymology. Patronymic, this new species is dedicated to Professor Dr. Richard Hermann Erdmann Klebs (1850–1911) from Königsberg, a world-renowned East-Prussian expert of Baltic amber and inclusions.

Figures

FIGURES 4 – 6. Xylolaemus richardklebsi sp. nov., holotype: 4 — habitus, dorsal view; 5 — habitus, ventral view; 6 — habitus, lateral view.

FIGURES 22 – 23. Reconstructions of habitus, dorsal view: 22 — Xylolaemus legalovi sp. nov.; 23 — X. richardklebsi sp. nov.; 24 — Diodesma slipinskii sp. nov.