A taxonomic review is provided for the Section I of the inquiline gallwasp genus Synergus, including the description of a new species from China, S. deqingensis Pujade-Villar, Wang & Chen sp. nov. and redescription of all previously known species of the section from the that region. Synergus jezoensis Uchida & Sakagami, 1948, a species previously considered of uncertain status from Japan, is treated herein as a valid species, and is redescribed and reported for the first time from China. Andricus mukaigawae (Mukaigawa, 1913) and its inquiline, S. japonicus, are reported for the first time from China. A key is provided to all four East Palearctic species in Section I of Synergus.

A taxonomic review is provided for the Section I of the inquiline gallwasp genus Synergus, including the description of a new species from China, S. deqingensis Pujade-Villar, Wang & Chen sp. nov. and redescription of all previously known species of the section from the that region. Synergus jezoensis Uchida & Sakagami, 1948, a species previously considered of uncertain status from Japan, is treated herein as a valid species, and is redescribed and reported for the first time from China. Andricus mukaigawae (Mukaigawa, 1913) and its inquiline, S. japonicus, are reported for the first time from China. A key is provided to all four East Palearctic species in Section I of Synergus.