Cathartosilvanus perkovskyi, Alekseev & Bukejs, 2021

Alekseev, Vitalii I. & Bukejs, Andris, 2021, Cathartosilvanus perkovskyi sp. nov. - first record of Silvanidae (Coleoptera: Cucujoidea) from Eocene Rovno amber, Baltic Journal of Coleopterology 21 (1), pp. 19-24 : 20-23

Cathartosilvanus perkovskyi sp. nov.

( Figs. 1–2 )

Type material. Holotype: collection number 6784 [ MAIG] (ex. coll. Jonas Damzen JDC 9454); adult, sex unknown. A compete beetle included in a transparent, yellow, elongate amber piece with dimensions of 44 mm × 12 mm and a maximum thickness of 5.5 mm; preserved without supplementary fixation. Syninclusions: fragments (legs) of unknown insect, and small detritus particle.

Type strata. Rovno amber, Upper Eocene .

Type locality. Rivne Oblast (region), Ukraine .

Etymology. The epithet of this new species is patronymic. The species is named in honor of our colleague Dr. Evgeny E. Perkovsky, leading researcher of insect inclusions in Rovno amber. Description. Measurements: body length 2.2 mm, maximum width 0.7 mm; head length 0.3 mm, head width (including eyes) 0.5 mm; pronotum length 0.6 mm, pronotum maximum width 0.6 mm; elytra length 1.3 mm, elytra maximum combined width 0.7 mm. Body elongate, almost parallel-sided, flattened; dorsum sparsely covered with fine, short, semi-erect setation, venter with less conspicuous very fine, recumbent setation; unicolorous dark brown (as preserved).

Head transverse, 1.7 × as wide as long, slightly narrower than anterior pronotal margin; densely covered with round, rather large punctation, nearly as large as eye facet, distance between punctures 0.2–1.0 × diameter of one puncture, puctures sparser and smaller in anterior portion of head; forehead almost flat, vertex slightly convex; frons without longitudinal sulcus laterally. Labrum with anterior margin widely rounded. Fronto-clypeal facets; widely separated, intraocular distance about 5.5 × transverse diameter of one eye. Temples absent. suture absent. Compound eyes rather large, hemispherical, strongly prominent, with coarse Antennal grooves apparently absent. Maxillary palpi short, with 4 palpomeres; palpomeres 3–4 transverse, palpomere 4 conical, elongate, about 2 × as long as wide, slightly narrower than palpomere 3. Terminal labial palpomere conical, nearly as wide as penultimate palpomere.

Antenna short, extending to middle of pronotum, stout, gradually thickening toward apex; 11-segmented, with indistinct, loose club apparently composed of 3 segments; covered with fine semi-erect setae; scape cylindrical, about as long as wide; pedicel subconical, elongate, about 1.7 × as long as wide; antennomere 3 conical, elongate, slightly shorter and narrower than pedicel; antennomeres 4–6 cylindrical, elongate; antennomeres 7–8 transverse, subequal in shape and size; antennomere 9 transverse, 1.6 × as wide as long, dilated apically, distinctly wider than antennomere 8, narrower than antennomere 10; antennomere 10 largest, strongly transverse, 1.8 × as wide as long; antennomere 11 ovoid, nearly as long as wide, narrower than antennomere 10. Pronotum as long as wide, widest in anterior one-third of its length, and slightly narrowed posteriad; pronotal punctation round, dense and rather large, punctures larger than eye facet, distance between smaller than diameter of one puncture, punctures sparser medially and almost contiguous laterally; disc widely impressed in posterior portion. Anterior pronotal margin almost straight; posterior margin with a distinct rim; lateral sides almost parallel-sided in anterior two-thirds and slightly oblique in posterior one-third of their lengths, distinctly crenulate, with distinct anterolateral denticle. Anterior angles nearly rectangular, not produced anteriorly; posterior angles obtuse. Prothoracic hypomeron flat, with sparse, small punctation. Prosternum with large and dense punctation, distance between punctures 0.3–1.5 × diameter of one puncture. Prosternal process elongate, dilated apically. Procoxal cavities closed.

Scutellar shield distinct, narrow, suboval, strongly transverse, about 2.5 × as wide as long, densely covered with fine punctation.

Elytra elongate, 1.9× as long as wide combined, subparallel-sided, slightly wider than pronotum, widest nearly at middle, rounded separately. Elytral punctation dense and small in anterior two-thirds and fine in posterior one-third; arranged in distinct rows, each elytron apparently with nine rows; scutellary striole absent; intervals covered with micropunctation, convex in anterior one-third of elytral length. Humeral angles rounded. Epipleura well developed, reaching elytral apex, widest at humeri, covered with sparse, fine punctures. Metaventrite with flat disc and fine median line; densely covered with rather large punctation, distance between punctures equal to 0.5–1.5 × diameter of one puncture, interspaces with micropunctation. Metepisterna long and narrow, with almost straight lateral margins, with longitudinal row of dense and large punctures.

Legs short and rather robust. Pro- and mesocoxa nearly round, metacoxa oval, transverse, not extending laterally to meet elytron; all coxae separated from each other: pro- and mesocoxae separated by distance slightly smaller than one coxal diameter, metacoxae separated by about 0.3× transverse diameter of metacoxa. Trochanters small, apparently without spines. Femora clavate, slightly flattened, simple (without denticles or teeth), with deep, longitudinal groove apicoventrally. Tibiae shorter than femora, dilated apically, slightly curved; with minute apical spine. Tarsi pentamerous; all tarsomeres simple, not lobed; tarsomeres 1–3 subcylindrical, slightly dilated apically; tarsomeres 2 and 3 equal in size; tarsomere 4 very small; tarsomere 5 longest, about as long as tarsomeres 1–4 combined. Tarsal claws simple, widely diverged, equal in size, long, about 0.3× as long as apical tarsomere.

Abdomen with five visible, similarly and freely articulated ventrites; ventrite 1 with open femoral line (diverging posteriorly from margin of metacoxal cavities), intercoxal process triangular with acute apex; ventrite 5 rounded apically; densely covered with rather large punctation, distance between punctures equal to 0.5–2.0 × diameter of one puncture, interspaces with micropunctation. Relative lengths (medially) of ventrites 1–5 equal to 20:15:12:9:?9.

Differential diagnosis. Cathartosilvanus perkovskyi sp. nov. can be distinguished by combination of characters: temples absent, pronotum not elongate, anterior angles of pronotum weakly developed, lateral sides of pronotum crenulate, and elytral intervals partially convex. Additionally, a new fossil species differs from similar in appearance (small body, pronotum as long as wide, and weakly developed anterior angles of pronotum) extant C. opaculus (LeConte, 1854) [distributed in Neotropic and southern Nearctic] in prosternal process without longitudinally rugose punctation and partially convex elytral intervals.

Cathartosilvanus perkovskyi sp. nov. from Rovno amber can be distinguished from the Baltic amber congeners by following key:

Figures

Fig. 1. Cathartosilvanus perkovskyi sp. nov., holotype, 6784 [MAIG], habitus: A – dorsal view; B – right lateral view

Fig. 2. Cathartosilvanus perkovskyi sp. nov., holotype, 6784 [MAIG]: A – details of head, ventrolateral view; B – details of head and pronotum, dorsal view.Abbreviations: a1-a11 – antennomeres 1- 11; mp3-mp4 – maxillary palpomeres 3-4; tlp – terminal labial palpomere