Acritus LeConte, 1853

Alekseev, Vitalii I. & Bukejs, Andris, 2021, The first extinct species of Acritus LeConte, 1853 (Histeridae: Abraeinae) from Eocene Baltic amber: a microscopic beetle inclusion studied with X-ray micro-computed tomography, Fossil Record 24 (2), pp. 223-231 : 224

Subgenus Acritus LeConte, 1853

Remarks

The specimen under study is assigned to the tribe Acritini within the subfamily Abraeinae based on the following: (1) the prosternum without anterior lobe; (2) body size less than 1.0 mm; (3) metatarsi with four tarsomeres (i.e. tarsal formula 5–5–4); (4) body form oval, not subcylindrical; and (5) pronotum evenly convex, without deep transverse furrow medially. The generic placement and attribution to Acritus is based on a combination of the following characters: (1) eyes present; (2) protibiae setose, without spinules or denticles; (3) scutellar shield small but visible; (4) pygidium without marginal stria; and (5) pronotum with a transverse line of large punctures along the basal margin.

The extant genus Acritus consists of two subgenera: Acritus s. str. with 118 described species and Pycnacritus Casey, 1916 with 9 species ( Mazur, 2011). The studied specimen does not have any oblique dorsal striae or vague impressions on the elytra, and it lacks any microsculpture between its fine elytral punctation. Therefore, a newly described fossil species was placed in the nominative subgenus.