Tetraneura sorini Hille Ris Lambers, 1970

Another species in the species group is T. sorini, which was described based on a specimen collected from a gall on a leaf of Ulmus sp. in Sapporo, Hokkaido. The host plant is most likely U. davidiana var. japonica, which is the most common elm species in Hokkaido. Hille Ris Lambers (1970) reported that this species is also distributed in Korea. Tetraneura sorini is sometimes confused with T. akinire sensu novo because the fundatrix first instars of T. sorini coexist with those of T. akinire and other Tetraneura species on the same elm tree. The fundatrix first instar of this species is very large in body size and parasitic to other Tetraneura species, usurping incipient galls of T. akinire or other Tetraneura species (Akimoto & Yamaguchi 1997; Muramatsu & Akimoto 2016); thus, T. sorini galls frequently coexist with those of other species. We redescribed this species based on the fundatrix first instar, emigrant and sexupara.