Endophloeus gorskii

Alekseev, Vitalii I. & Bukejs, Andris, 2016, New Zopheridae (Coleoptera: Tenebrionoidea) from Baltic amber, Zootaxa 4178 (3), pp. 409-427 : 415-420

E. gorskii Alekseev & Bukejs sp. nov.

( Figs 13–21 )

Type material. Holotype: Nr. 8291 [CAG], “Holotype / Endophloeus gorskii sp. nov. / des. Alekseev V.I. & Bukejs A.” [red printed label]; male. Complete beetle with partially exposed aedeagus is included in a small, transparent, square amber piece (6 × 6 × 4 mm), that is yellowish in colour, and preserved without supplementary fixation. Syninclusions include a few stellate Fagaceae trichomes and two gas vesicles.

Paratype: Nr. 8313 [ CAG], “ Paratype / Endophloeus gorskii sp. nov. / des. Alekseev V.I. & Bukejs A.” [red printed label]; male. Complete beetle with partially exposed aedeagus, included in a small, transparent, subtriangular amber piece (23 × 13 × 7 mm), that is yellowish in colour, and preserved without supplementary fixation. Ventral anterior portion of the specimen is obscured by “milky” amber opacity. Syninclusions is one specimen of Nematocera (Diptera), one damaged ant specimen ( Hymenoptera : Formicidae ), and few small gas vesicles.

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

Type locality. Baltic Sea coast, Gdańsk , Poland; Baltic amber, Upper Eocene, Prussian Formation.

Differential diagnosis. Endophloeus gorskii sp. nov. differs from extant species of the genus in the following combination of characters: pronotal admedian costae joined together in posterior half; elytral interval 3 with ridgelike protuberances basally; pronotum densely granulated; elytra with short scale-like setae; and smaller body size (2.8–3.0 mm).

Description. Body length about 2.9 mm, maximal width 1.3 mm; body elongate, nearly parallel-sided, convex dorsally and almost flat ventrally; unicolorous black.

Head. Broad, distinctly widened in front of eyes, with anterior portion flat and frons slightly convex; lateral margins convex above antennal insertions and narrowing to anterior margin; covered with moderately large round granules, each bearing lanceolate scale-like seta. Compound eyes small, moderately convex; interfacetal setae not apparent. Clypeus transverse, slightly convex, anteriorly straight; covered with pale setae (distinctly longer than scale-like setae). Maxillary palpi 4-segmented, short; palpomere 4 widely ovate with pointed apex, about 1.8× as long as wide, distinctly longer than palpomeres 2–3 combined. Labial palpus 3-segmented, palpomere 3 ovalshaped and largest. Antennae short, extending to base of pronotum; 11-segmented with distinct 2-segmented club, sparsely covered with dark, semierect setae; scape and pedicel subcylindrical, nearly equal in length (not distinctly visible in examined specimen); antennomere 3 elongate, about 1.5× as long as antennomere 4, and distinctly narrower than pedicel; antennomeres 4–9 subequal in size and shape, slightly dilated distally, antennomere 9 narrow, 0.6× as wide as antennomere 10; antennomere 10 transverse, dilated distally, 0.7× as long as wide; antennomere 11 widely ovate with rounded apex, 1.9× as long as wide, and 1.5× as long as antennomere 10.

Thorax. Pronotum transverse, 1.6× as wide as long, widest in posterior one-third, almost as wide as elytra; pronotal disc convex, lateral sides widely explanate; densely covered with large granules (slightly larger than granules on frons), distance between granules smaller than diameter of one granule, each granule bearing lanceolate, scale-like, erect seta. Anterior margin arcuate, convex with shallow emargination medially; lateral margins widely convex, denticulate, each denticle bearing lanceolate scale-like seta; posterior margin convex. Anterior angles acute, strongly protruding; posterior angles indistinct. Pronotal sub-basal sulcus distinct. Pronotal disc with two admedian costae: parallel and narrowly separated in anterior one-fourth, curved outward and forming rounded area between costae near midlength, joined together in posterior portion, and narrowly separated at posterior margin. Prosternum densely covered with granules; procoxa nearly round, shagreened; procoxal cavities open posteriorly; prosternal process moderately large, about 1.3× as wide as transverse diameter of procoxa, lateral margins almost straight, posterior margin slightly projecting posteriorly.

Scutellum small, subpentagonal, with sparse short setae. Elytra almost parallel-sided, tapered at apex, strongly convex with explanate lateral sides; about 1.6× as long as wide. Humeral angles rounded. Basal margin concave in scutellar area, with small denticles; lateral margins denticulate, each denticle bearing lanceolate scale-like seta; in basal half, denticles as large as those on pronotal lateral margins, gradually becoming smaller apicad. Punctures arranged in regular striae, each puncture with lanceolate, scale-like, erect seta; intervals flat; sutural interval with fine setae (distinctly visible in basal half); distance between striae approximately 1.5–2× diameter of single puncture. Scutellary striole absent. Elytral surface not clearly visible in examined specimen because of milky amber coating. Intervals 3 and 7 with ridge-like protuberances basally, interval 5 with less distinct protuberance at base, intervals 2–5 with few additional small protuberances medially and apically, some indistinct; protuberances bearing lanceolate scale-like erect setae.

Epipleura with small granules; wide, in basal one-fourth about 2.2× as wide as metepisternum; widest in basal half, slightly narrowing posteriorly, reaching elytral apex. Mesosternum shorter than ventrite 1, densely covered with granules; mesocoxa nearly round, distance between mesocoxae narrower than transverse diameter of masecoxa. Metaventrite slightly convex, with small granules; metacoxae transverse, elongate; metepisternum narrow, about 6× as long as wide, slightly dilated anteriad, with small granules, anterior margin oblique, lateral margins slightly emarginate. The ratio of lengths of mesoventrite to metaventrite to abdomen: 3-5-11.

Abdomen. With sparse, fine punctures; abdominal intercoxal process narrow, triangular. Ventrite 5 with widely rounded posterior margin. Ventrite length ratios: 20-17-15-12 -20. Apex of aedeagus ( Fig. 14–15 ).

Legs. Short, femora slightly widened; femora and tibiae subequal in length, with lanceolate scale-like setae dorsally, remaining surface with fine setae; tibiae straight. Tarsi tetramerous. Tarsi nearly 0.8× as long as tibia, tarsomeres 1–3 short, subequal in lenght, tarsomere 4 about 1.5× as long as tarsomeres 1–3 combined. Claws large, simple, dilated at base.

Note: Paratype slightly differs from holotype: body length 2.8 mm, maximal width 1.3 mm; appearing unicolorous rufous. Elytral punctures arranged in 9 regular striae. Pronotal costae and elytral protuberances less convex and distinct than in holotype. In our opinion, both studied specimens are conspecific.

Etymology. Patronymic, this new species is named after Andrzej Górski (Bielsko-Biała, Poland), who enabled us to study these specimens.

Figures

FIGURES 13 – 18. Endophloeus gorskii sp. nov., holotype: 13 — head and pronotum, dorsal view; 14 — apical portion of abdomen with partly exposed aedeagus, ventral view; 15 — apex of aedeagus, dorsal view; 16 — apical portion of right antenna; 17 — last mesotarsomere and claws; 18 — details of head, frontal view.

FIGURES 19 – 21. Endophloeus gorskii sp. nov., paratype: 19 — habitus, dorsal view; 20 — habitus, ventral view; 21 — habitus, lateral view.