The genus Gonioctena Chevrolat, 1836 is one of the largest genera of the subfamily Chrysomelinae with approximately110 valid species in nine subgenera distributed in the Holarctic and Oriental Regions (Cho 2016). Their larval morphologyis relatively well known, especially in Europe, the Russian Far East and Japan. Larvae of 41 species have been describedbased primarily on the tubercles and chaetotaxy (Kimoto 1962; Medvedev & Zaitzev 1978; Baselga 2008, 2010, etc.).However, their relationship is still incomplete because descriptions of many species are too brief and more than half ofthe species are completely unknown. Here, we redescribe in detail the last instar larva of Gonioctena coreana (Bechyně),G. gracilicornis (Kraatz), G. jacobsoni (Ogloblin & Medvedev) and G. viminalis (Linnaeus) from South Korea. Noteson biology, host plant and ovoviviparity are also provided.

The genus Gonioctena Chevrolat, 1836 is one of the largest genera of the subfamily Chrysomelinae with approximately 110 valid species in nine subgenera distributed in the Holarctic and Oriental regions. The Gonioctena mauroi species-group of the subgenus Brachyphytodecta Bechyně, 1948 is proposed to include four species: Gonioctena mauroi Cho & Borowiec, 2016 (Vietnam), G. medvedevi Cho & Borowiec, 2016 (Vietnam), G. kuatunensis sp. nov. (China) and G. longshengensis sp. nov. (China). They are characterized by the presence of setae on the aedeagus, which is unique within the subgenus. A key to the species, habitus photographs, illustrations of diagnostic characters and a distribution map are provided. Ovoviviparity is newly recorded in G. longshengensis sp. nov.

The genus Gonioctena Chevrolat is distributed in the Holarctic and Oriental regions, with more than 80 species. Many species of the genus have great similarity in external morphology and coloration, often cause misidentifications. Thus, the shape of the aedeagus is mainly used to distinguish closely related species. Fifty-four species, more than half of the known taxa, occur in northeastern Asia, including 18 species in the Russian Far East, 29 in China, 11 in Korea, and 18 in Japan. Among these, G. gracilicornis Kraatz (type locality: Amur) is widely distributed in Russia, China, Mongolia and Korea. However, extensive investigation on Gonioctena in Korea revealed that the Korean population of G. gracilicornis differs from that of the Russian by the coloration, the puncturation of pronotum, and the shape of aedeagus. The purpose of this study is to describe a new species of Gonioctena that was previously misidentified as G. gracilicornis. A key to Korean Gonioctena, distribution, and host plant are also provided.