Closterocerus Westwood 1833 is a Chalcidoidea and not an Ichneumonidae as the following Zoological Record descriptor of this reference stated. none The taxonomic status and delimitation of the genus Closterocerus Westwood is discussed, partly on the basis of new characters. The following genera are synonymized with Closterocerus: Achrysocharis Girault (maintained as subgenus), Achrysocharella Girault, Cecidiophaga Erdoes, Chrysocharidia Erdoes, Halochariessa Erdoes, Halocharis Erdoes, Moserina Delucchi, Pseudochrysocharis Girault, Wolffiella Krausse. The genus Chrysonotomyia are transferred to Closterocerus. The Nearctic species of Closterocerus are revised, and a key to the species is given. Twenty-one species are recognized, of which 8 are described as new: brachyphagus, carolinae, cyaneus, longus, nitidus, nius, texanus, violaceus. Four new synonyms are suggested: Chrysonotomyia baliosa Yoshimoto and C. cunicularia Yoshimoto = Closterocerus cinctipennis Ashmead; Pleurotropis tricinctus Ashmead and Closterocerus winnemanae Crawford = Closterocerus trifasciatus Westwood. Seven Nearctic species are newly transferred to Closterocerus: Achrysocharis partifuscipennis Ashmead and Moserina maculata Delucchi from Omphale, Achrysocharis phenacaspia Yoshimoto, A. spiniformis Moser, A. vesiculis Moser, Chrysonotomyia solidaginis Yoshimoto and Wolffiella ruforum Krausse all from Chrysonotomyia. The species Closterocerus damastes Walker is reassigned to Closterocerus from Chrysonotomyia. The Palearctic species Achrysocharis lyonetiae Ferriere, Nesomyia cinctiventris Ashmead, Halochariessa germanica Erdoes, Entedon lanassa Walker, Achrysocharis smaragdula Graham, Chrysonotomyia yamagishii Kamijo, Halochariessa pannonica Erdoes and Halocharis transsylvanica Erdoes are newly transferred to Closterocerus from Chrysonotomyia. A neotype is designated for Closterocerus cinctipennis. Lectotypes are designated for Closterocerus utahensis Crawford, C. winnemanae and Pleurotropis tricinctus. Systematics; Nomenclature; New taxa; Type material; Combination; Synonymy; Taxonomy; Taxonomic position; Status; Key; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Land and freshwater zones; Nearctic region; North America; USA Insecta; Hymenopteran parasites; Closterocerus; Parasite systematics & host parasite list; Nearctic region; Hymenopteran parasite systematics & host parasite list Brachys tesselatus (Buprestidae); Hymenopteran parasites; Closterocerus (Closterocerus) brachyphagus; New parasite species; Georgia USA; Johnson County; New hymenopteran parasite species Closterocerus (Ichneumonidae); Insect hosts; Systematic revision & host parasite list; Nearctic region; Systematic revision & host list Closterocerus (Closterocerus) brachyphagus (Ichneumonidae); Coleopteran hosts; Brachys tesselatus; New parasite species; Georgia USA; Johnson County; New species from coleopteran host Closterocerus (Closterocerus) brachyphagus (Ichneumonidae); Sp nov; Georgia USA, host Brachys tesselatus (Coleoptera); P. 3, fig'd Closterocerus (Closterocerus) cinctipennis Ashmead 1888 (Ichneumonidae); Syn nov; Chrysonotomyia cunicularia Yoshimoto 1980, p. 4; Syn nov; Chrysonotomyia baliosa Yoshimoto 1980, p. 4 Closterocerus (Closterocerus) lyonetiae (Ferriere 1952) (Ichneumonidae); Comb nov; Transferred from; Chrysonotomyia, p. 23 Closterocerus (Closterocerus) nitidus (Ichneumonidae); Sp nov; Oregon, host unknown; P. 10, fig'd Closterocerus (Closterocerus) ruforum (Krausse 1917) (Ichneumonidae); Comb nov; Transferred from; Chrysonotomyia, p. 10 Closterocerus (Closterocerus) trifasciatus Westwood 1833 (Ichneumonidae); Syn nov; Pleurotropis tricinctus Ashmead 1888, p. 11; Syn nov; C. winnemanae Crawford 1912, p. 11 Closterocerus Westwood 1833 (Ichneumonidae); Syn nov; Halocharis Erdos 1951, p. 2; Syn nov; Moserina Delucchi 1962, p. 2; Syn nov; Halochariessa Erdos 1956, p. 2; Syn nov; Achrysocharella Girault 1913, p. 2; Syn nov; Chrysocharidia Erdos 1956, p. 2; Syn nov; Pseudochrysocharis Girault 1913, p. 2; Syn nov; Wolffiella Krausse 1917, p. 2; Syn nov; Cecidiophaga Erdos 1966, p. 2; Key to species; Nearctic region; P. 2 Closterocerus cinctipennis Ashmead 1888 (Ichneumonidae); Neotype designated; P. 9 Closterocerus utahensis Crawford 1912 (Ichneumonidae); Lectotype designated; P. 13 Closterocerus winnemanae Crawford 1912 (Ichneumonidae); Lectotype designated; P. 12; New synonym; Of C. (Closterocerus) trifasciatus Westwood 1833, p. 11 Achrysocharella Girault 1913 (Eulophidae); New synonym; Of Closterocerus Westwood 1833, p. 2 Achrysocharis Girault 1913 (Eulophidae); Downgraded to; Closterocerus (Achrysocharis), p. 21 Cecidiophaga Erdos 1966 (Eulophidae); New synonym; Of Closterocerus Westwood 1833, p. 2 Chrysocharidia Erdos 1956 (Eulophidae); New synonym; Of Closterocerus Westwood 1833, p. 2 Chrysonotomyia Ashmead (Eulophidae); Status; P. 20 Chrysonotomyia baliosa Yoshimoto 1980 (Eulophidae); New synonym; Of Closterocerus (Closterocerus) cinctipennis Ashmead 1888, p. 4 Chrysonotomyia cinctiventris (Ashmead 1904) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 23 Chrysonotomyia cunicularia Yoshimoto 1980 (Eulophidae); New synonym; Of Closterocerus (Closterocerus) cinctipennis Ashmead 1888, p. 4 Chrysonotomyia damastes (Walker 1847) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 14 Chrysonotomyia germanica (Erdos 1956) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 23 Chrysonotomyia lanassa (Walker 1839) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 23 Chrysonotomyia lyonetiae (Ferriere 1952) (Eulophidae); Referred to; Closterocerus (Closterocerus), p. 23 Chrysonotomyia pannonica (Erdos 1956) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 23 Chrysonotomyia phenacaspia (Yoshimoto 1972) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 17 Chrysonotomyia ruforum (Krausse 1917) (Eulophidae); Referred to; Closterocerus (Closterocerus), p. 10 Chrysonotomyia smaragdula (Graham 1963) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 23 Chrysonotomyia solidaginis Yoshimoto 1980 (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 17 Chrysonotomyia spiniformis (Moser 1965) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 18 Chrysonotomyia transsylvanica (Erdos 1951) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 23 Chrysonotomyia vesiculis (Moser 1965) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 19 Chrysonotomyia yamagishii Kamijo 1979 (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 23 Closterocerus (Achrysocharis) Giraud 1913 (Eulophidae); Downgraded from; Achrysocharis, p. 21 Closterocerus (Achrysocharis) carolinae (Eulophidae); Sp nov; North Carolina, host unknown; P. 13, fig'd Closterocerus (Achrysocharis) cinctiventris (Ashmead 1904) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 23 Closterocerus (Achrysocharis) cyaneus (Eulophidae); Sp nov; California, host unknown; P. 14, fig'd Closterocerus (Achrysocharis) damastes Walker 1847 (Eulophidae); Combination revalidated transferred back from; Chrysonotomyia, p. 14 Closterocerus (Achrysocharis) germanica (Erdos 1956) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 23 Closterocerus (Achrysocharis) lanassa (Walker 1839) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 23 Closterocerus (Achrysocharis) longus (Eulophidae); Sp nov; Florida, host unknown; P. 15, fig'd Closterocerus (Achrysocharis) maculatus (Delucchi 1962) (Eulophidae); Comb nov; Transferred from; Omphale, p. 15 Closterocerus (Achrysocharis) nius (Eulophidae); Sp nov; Missouri, host unknown; P. 16, fig'd Closterocerus (Achrysocharis) pannonica (Erdos 1956) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 23 Closterocerus (Achrysocharis) partifuscipennis (Girault 1916) (Eulophidae); Comb nov; Transferred from; Omphale, p. 16 Closterocerus (Achrysocharis) phenacaspia (Yoshimoto 1972) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 17 Closterocerus (Achrysocharis) smaragdula (Graham 1963) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 23 Closterocerus (Achrysocharis) solidaginis (Yoshimoto 1980) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 17 Closterocerus (Achrysocharis) spiniformis (Moser 1965) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 18 Closterocerus (Achrysocharis) texanus (Eulophidae); Sp nov; Texas, host unknown; P. 18, fig'd Closterocerus (Achrysocharis) transsylvanica (Erdos 1951) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 23 Closterocerus (Achrysocharis) vesiculis (Moser 1965) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 19 Closterocerus (Achrysocharis) violaceus (Eulophidae); Sp nov; California, host unknown; P. 20, fig'd Closterocerus (Achrysocharis) yamagishii (Kamijo 1979) (Eulophidae); Comb nov; Transferred from; Chrysonotomyia, p. 23 Halochariessa Erdos 1956 (Eulophidae); New synonym; Of Closterocerus Westwood 1833, p. 2 Halocharis Erdos 1951 (Eulophidae); New synonym; Of Closterocerus Westwood 1833, p. 2 Moserina Delucchi 1962 (Eulophidae); New synonym; Of Closterocerus Westwood 1833, p. 2 Neochrysocharis Kurdjumov (Eulophidae); Status; P. 23 Omphale maculatus (Delucchi 1962) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 15 Omphale partifuscipennis (Girault 1916) (Eulophidae); Referred to; Closterocerus (Achrysocharis), p. 16 Pleurotropis tricinctus Ashmead 1888 (Eulophidae); Lectotype designated; P. 12; New synonym; Of Closterocerus (Closterocerus) trifasciatus Westwood 1833, p. 11 Pseudochrysocharis Girault 1913 (Eulophidae); New synonym; Of Closterocerus Westwood 1833, p. 2 Wolffiella Krausse 1917 (Eulophidae); New synonym; Of Closterocerus Westwood 1833, p. 2