A New Subgenus and Species of Priochirus from Mid-Cretaceous Kachin Amber (Coleoptera: Staphylinidae: Osoriinae) †

SIMPLE SUMMARY: Despite the extant diversity of the rove beetle subfamily Osoriinae, its fossil record remains meagre. The present study reports a new species Priochirus (Eopriochirus) trisclerite subgen. et sp. nov. from Kachin amber (mid-Cretaeous: Cenomanian, ca. 99 Ma). The discovery not only enriches the fossil record of Osoriinae but adds to our understanding of its ancient origin and diversification. With new species described in the present paper, 3 species of osoriines are known from Mesozoic Kachin amber. ABSTRACT: As one of the largest families of beetles (Coleoptera), the Staphylinidae (rove beetles and their relatives) are rich not only in extant species but also in a comparatively robust fossil record. Despite this preponderance of available fossil material, fossils of the diverse subfamily Osoriinae remain rare. Here, we describe a new ososriine species, Priochirus trisclerite sp. nov., from the mid-Cretaceous amber of Myanmar. The new specimen is similar to the only other definitive fossil of the genus, Priochirus thayerae Yamamoto 2019, and both are placed in the extinct subgenus Eopriochirus subgen. nov. The new species differs noticeably in a number of morphological details in relation to the submentum, gular sutures and protibial crenulae. The new fossil provides further evidence for understanding the radiation of staphylinoid beetles.