First occurrence of the little-known genus Noteriades (Hymenoptera, Megachilidae) from Vietnam: discovery of a new species and a key to the Southeast Asian fauna.

The little-known megachiline genus Noteriades Cockerell, 1931 is recorded from Vietnam for the first time. A new species, Noteriadeshangkia Tran, Engel & Nguyen sp. nov. is described and figured based on a series of females collected from the provinces of the northern and central highlands of Vietnam. The genus is briefly discussed and a new subtribe is established, Noteriadina Engel, Tran & Nguyen subtrib. nov. of Megachilini. Lastly, an identification key and distribution map are provided for those species occurring in Southeast Asia.

Taxonomic studies on the genus Orancistrocerus van der Vecht, 1963 (Hymenoptera: Vespidae: Eumeninae) from Vietnam, with description of a new species.

Two species of the genus Orancistrocerus van der Vecht, 1963 from Vietnam are recorded. Of them, a new species, O. altus sp. nov. from Lang Son province in the northern part of Vietnam is described and illustrated. In addition, one subspecies, O. aterrimus nigriceps van der Vecht, 1963 is newly recorded from China.

The genus Chalybion Dahlbom, 1843 (Hymenoptera: Sphecidae) from Northwest Vietnam, with description of a new species.

The genus Chalybion Dahlbom, 1843 from northwest Vietnam is studied. Six species of the genus are recorded for the area. Of these, C. dolichothorax (Kohl, 1918) and C. gracile Hensen, 1988 are new records, whereas C. tanvinhensis sp. nov. is described as a new species. Notes on the nest of the new species and keys to both sexes of the six species reported from northwest Vietnam are provided.