Xylolaemus legalovi

Alekseev, Vitalii I. & Bukejs, Andris, 2016, New Zopheridae (Coleoptera: Tenebrionoidea) from Baltic amber, Zootaxa 4178 (3), pp. 409-427 : 410-412

X. legalovi Alekseev & Bukejs sp. nov.

( Figs 1–3 , 22 )

Type material. Holotype: Nr. 572-2 [CCHH] “Holotype / Xylolaemus legalovi sp. nov. / des. Alekseev V.I. & Bukejs A.” [red hand-written label]; sex unknown. Complete beetle is included in small, triangular, red amber piece embedded in block of GTS-polyester resin with dimensions 13 × 10 × 4 mm. Syninclusions consist of small pieces of organic material. Basal portion of head and anterior portion of pronotum are obscured by large wood piece; epipleura, abdomen, and ventral portions of thorax are not visible due to milky-white coating and nearopacities of amber matrix.

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 legalovi sp. nov. differs from extant species of the genus in the following combination of characters: small body size, transverse pronotum with denticulate lateral margins, elytra with 14 fascicules (setose patches) and regular rows of oval recumbent scales. This new species can be distinguished from fossil Xylolaemus sakhnovi Alekseev & Lord, 2014 by its transverse dilated antennomere 10, and the form and sculpture of the pronotum and head. Xylolaemus legalovi sp. nov. is distinguished from X. richardklebsi sp. nov. by the presence of fascicules (setose patches) on the dorsal surface of the elytra, larger pronotal granulation, and the hemispherical antennomere 11.

Description. Body length about 3.5 mm, maximal width 1.3 mm; body elongate, nearly parallel-sided, flattened dorsally; body and appendages preserved with uniformly dark grey colour.

Head. Slightly longer than wide; widest between antennae, covered with moderately large, round unisetose granules. Anterior clypeal margin straight. Lateral margins convex above antennal insertions and narrowing to anterior margin. Eyes large, prominent, conical, with coarse facets. Interfacetal setae not apparent (even at 56× magnification). Maxillary palpus 4-segmented, short; palpomere 4 widely oval, mucronate, slightly longer and wider than palpomere 3. Labial palpus 3-segmented, palpomere 3 oval-shaped, 2× as long as palpomere 2.

Antennae short, extending to base of pronotum; 11-segmented, sparsely covered with dark, semierect setae; with distinct, finely pubescent, 2-segmented club. Scape, pedicel, and antennomeres 3–4 cylindrical; antennomeres 5–9 rounded, slightly wider than long; antennomere 10 transverse, dilated distally, 0.8× as long as wide; antennomere 11 hemispherical, almost as long as wide.

Thorax. Pronotum transverse, 1.3× as wide as long, widest in anterior one-third; pronotal disc slightly flattend, lateral sides explanate; densely covered with large unisetose granules (slightly larger than granules on frons), distance between granules smaller than diameter of one granule. Anterior margin arcuate; lateral margins nearly parallel-sided, denticulate (each with seven or eight denticles); posterior margin slightly rounded; anterior angles triangular, acute, prominent, reaching posterior one-third of eye; posterior angles obtuse. Sculpture of pronotal disc similar to head sculpture, but granules of disc larger and denser (distance between granules equal to 0.3–0.4× diameter of one granule).

Scutellum small, rounded. Elytra elongate (elytral length 2.3 mm, maximum elytral width 1.3 mm), convex, nearly parallel-sided, 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 with fine secondary punctures in apical one-third of elytra, distance between striae approximately 1.5–2.0× diameter of single puncture. Elytra with rows of recumbent oval scales partially covering punctures dorsally and fascicules (setose patches) ( Fig. 22 ), consisting of group of semirecumbent, pale, lanceolate scales. Scutellary striole apparent, consisting of three punctures. Hind wings not visible.

Abdomen. With five visible, similarly articulated ventrites.

Legs. Tarsi tetramerous. Metatarsomere 4 as long as metatarsomeres 1–3 combined; pro- and mesotarsomere 4 slightly shorter than combined length of tarsomeres 1–3. Tarsal claws simple, large, equal in size, length about onethird of tarsomere 4.

Etymology. Patronymic, this new species is dedicated to our dear colleague and expert in fossil weevils, Dr. Andrei A. Legalov (Novosibirsk, Russia).

Figures

FIGURES 1 – 3. Xylolaemus legalovi sp. nov., holotype: 1 — habitus, dorsal view; 2 — details of forebody, ventral view; 3 — habitus, ventral view.

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