Atomariini LeConte, 1861

Tribe Atomariini LeConte, 1861

Genus Atomaria Stephens, 1829

Atomaria (Atomaria) saxonica Lyubarsky et Perkovsky, 2018

Figs 1–2 View Figure 1 View Figure 2

New material. SIZK UA- 29618, Rovno Oblast, Rovno amber, late Eocene.

Redescription. Length of body 1.35 mm, body elongate ( Fig. 1A View Figure 1 ), moderately convex, covered with slightly curved, decumbent pale pubescence of moderate length. Body, legs and antennae entirely dark brown.

Head transverse, finely punctured, distance between punctures slightly greater than diameter of puncture; with hemispherical facetted eyes; length of eye almost 2 times less than length of head. Eye normally developed, with 12-14 facets in external margin of eye (when counted from dorsal view at the greatest length of the eye) ( Figure 1C View Figure 1 ). Antennae short, slender, with club not extending beyond base of pronotum when directed posteriad ( Figs 1A, 1C View Figure 1 , 2A View Figure 2 ), joints of flagellum elongate, about 1.5 times as long as broad, antennomere 1 elongated, slightly curved, a little longer than 2 nd, 1.4 times as long as broad, antennomeres 3–6 a little shorter. Antennomere 2 slightly shorter than 1 st, sometimes equal to it. Antennomere 3 1.3 times as long as broad, antennomeres 3 and 5 longer than 4 th and 6 th, antennomeres 7 and 8 slightly wider, subquadrate, antennomere 7 narrower than 8 th. Antennomere 9 slightly transverse, 1.6 times as broad as long, narrower than 10 th, antennomere 10 distinctly transverse, antennomere 11 widely oval, with rounded apex, twice longer than 10 th, slightly compressed ( Figure 2B View Figure 2 ). Antennae insertions widely separated basally.

Pronotum weakly transverse, of approximately same width from middle to base, 1.2-1.3 times as broad as long, weakly and finely punctured, distance between punctures equal to two puncture diameters. Pronotal disk convex, anterior margin not sinuate or weakly sinuate, anterior angles without thickening or callosity. Lateral margin visible from above only in the basal half of pronotum. Base of pronotum with median depression, with basal pits ( Figs 1A View Figure 1 , 2A View Figure 2 ); posterolateral angles rectangular. Hind margin finely bordered, basal edge lobed. Prosternum finely punctured, distance between punctures greater than diameter of puncture ( Figure 1B View Figure 1 ). Lines on the prosternal process absent, prosternal process not vaulted ( Figure 1B View Figure 1 ). Hind coxae set not far apart. Tarsal formula 5-5-5. Tibia slender, parallel-sided, with two spurs. Longitudinal metasternal line absent. Meta-intercoxal process wider than long. Femoral line absent. Ventrite 5 evenly arcuate; ventrite 5 without crenulations, surface unmodified ( Figs 1B View Figure 1 , 2A View Figure 2 ). Scutellum small, pentagonal, transverse. Elytra shortoval, moderately convex, humeral corners rounded, weakly curved at sides ( Figure 1B View Figure 1 ), maximum breadth of elytra in first third of their length, 2.1-2.5 times as long as pronotum, 1.2-1.4 times as long as broad ( Figure 1A View Figure 1 ). Elytral surface shining, moderately closely punctured, punctures in basal part slightly stronger than those on pronotal disk, and approximately 1.5 diameters apart their lateral neighbours on an average. Elytral impression absent. Wings present.

Remarks. Atomaria saxonica has been described from Bitterfeld amber ( Lyubarsky & Perkovsky 2018). In previous publications, all Eocene amber species were assigned to the subgenus Atomaria (Anchicera) . Due to nomenclatural changes, the same species are now assigned to the subgenus Atomaria (s. str.).

Among the Eocene amber species, A. saxonica differs in a combination of characters: size small, antennomere 3 distinctly elongated, 1.3× as long as wide, slightly shorter than antennomere 2, antennomere 7 about as long as antennomeres 6 and 8 combined. Pronotum indistinctly narrowed towards base ( Lyubarsky & Bukejs 2022). A. saxonica differs from the similarly sized A. telnovi primarily in the pronotum, which is almost not narrowed towards the base ( A. telnovi : pronotum clearly narrowed basally). A. saxonica differs from the similarly sized A. archibaldi in the antennomere 3 distinctly elongated ( A. archibaldi : antennomere 3 approximately equal in length to width).

A total of nine species of the genus Atomaria Stephens, 1829 have been reported from Eocene amber: five species from Rovno amber, four species from Baltic amber and one species from Bitterfeld amber.