A new species of from Vietnam and an updated key to species of the genus (Hymenoptera, Apidae).

The rare bee genus Lieftinck, 1974 is recorded for the first time from Vietnam. The genus is represented by a new species, Tran, Engel & Nguyen, , from Cao Bang Province and can be most easily confused with Wu from China. The species is most easily differentiated by the unique form of the male terminalia but can also be distinguished by differences in integumental and setal coloration.

The potter wasp genus from Vietnam, with descriptions of three new species and a new country record (Hymenoptera, Vespidae, Eumeninae).

Species of the potter wasp genus van der Vecht (Eumeninae: Odynerini) occurring in Vietnam are presented. Seven species have been recorded from Vietnam. Of them, three species are described as new to science: Nguyen, Tran & MT Nguyen, , Nguyen & AD Nguyen, , and Nguyen & Engel, , and one species, (Fabricius, 1804), is recorded from Vietnam for the first time.

The bee genus in Vietnam: descriptions of five new species and the first male of (Hymenoptera, Megachilidae).

The Vietnamese fauna of bees in the Cockerell (Megachilinae, Anthidiini) is reviewed. Seven species are recognized, representing two subgenera. Five new species are described and figured as: Anthidiellum (Clypanthidium) nahang Tran, Engel & Nguyen, , A.

Two new species of Trichrysis Lichtenstein (Hymenoptera: Chrysididae) from Vietnam and China, with taxonomic notes on other species from the Oriental region.

Two new species of the genus Trichrysis Lichtenstein, belonging to the cyanea species group, are described from northeastern Vietnam (Cao Bang Province) and China (Yunnan Province) as new for science: T. sinica Rosa, Nguyen & Wiśniowski, sp. nov.

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

The little-known megachiline genus Cockerell, 1931 is recorded from Vietnam for the first time. A new species, Tran, Engel & Nguyen 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 of Megachilini.

A new genus of minute stingless bees from Southeast Asia (Hymenoptera, Apidae).

A new genus of minute stingless bees (Meliponini: Hypotrigonina) is described from Southeast Asia. Engel & Nguyen, , is based on the type species Engel, recorded from Vietnam, Thailand, Laos, Cambodia, and southern China. The species was previously considered an enigmatic member of Moure, but is removed to a new genus based on its unique male terminalia that differs considerably from that of and instead shares resemblances with Moure, and the presence of yellow maculation (also similar to that of ).

Contribution to the genus Pararrhynchium de Saussure (Hymenoptera: Vespidae: Eumeninae), with description of two new species from Vietnam.

Two new species of the genus Pararrhynchium de Saussure are described as new to science: P. simsanum Nguyen and Tran, sp. nov.

Additional knowledge respecting taxonomy of the social wasp genus Ropalidia (Hymenoptera: Vespidae: Polistinae) from Vietnam, with new records of three species and an updated key to species.

Species composition of social wasps of the genus Ropalidia from Vietnam is reported, with 24 species having been recorded. Of those, three species are newly recorded for the Vietnamese fauna, namely Ropalidia binghami van der Vecht, 1941, R. parartifex Tan van Achterberg, 2014 and R.