Balticeler kerneggeri gen. nov., sp. nov., an enigmatic Baltic amber fossil of the ground beetle subfamily Trechinae (Coleoptera, Carabidae)

Balticeler kerneggeri gen. nov. , sp. is described based on six fossil specimens preserved in Eocene Baltic amber and imaged using light microscopy X-ray micro-computed tomography. Based certain characters observed the species it considered a “middle grade” Carabidae, outside of large family Harpalinae (as possesses scrobal seta, lack which synapomorphy that subfamily), but possessing four synapomorphies indicate belongs to clade carabids including (anisochaetous Grade B antennal cleaner, conjunct mesocoxae, closed procoxal cavities, well-developed external lobe metepimeron). This remarkable beetle has several striking features, externally-visible sexually dimorphic characters, lateral borders pronotum, very long thin mandibles maxillae. In combination, these states are unique within Carabidae. We consider presence dorsally completely open aedeagal median as with subfamily Trechinae, pubescent relatively second antennomere 4+2+2 pattern umbilicate setae supertribe Trechitae, quadrisetose clypeus Trechitae Bembidarenini + Trechini sensu Maddison et al. (2019). As lacks Trechini, we propose member stem group clade.