Taxonomy of the genus Chalybion Dahlbom, 1843 (Hymenoptera: Sphecidae) from Vietnam, with description of a new species

Based on the specimens deposited in the Institute of Biology, Hanoi, Vietnam and the Museum für Naturkunde Berlin, Berlin, Germany, the nest-renting wasp genus Chalybion Dahlbom from Vietnam is studied. Eight species of the genus are recorded from the country. Of these, Chalybion iridescens Pham & Ohl, sp. nov. is described and illustrated.

Keys to both sexes of the Vietnamese Chalybion species, new distributional records for some species, and a key to the species of the Chalybion madecassum group are provided. The status of Chalybion clarebaltazarae Abenis & Lit, 2019 and Chalybion stephenreyesi Abenis & Lit, 2019 from the Philippines is critically discussed. Both species are probably invalid, but require further investigations.