Allurus Foerster, 1863

Diagnosis. Tarsal claws cleft (couplet 15A). Forewing vein 3RS complete to wing margin (Fig. 1B). Forewing vein M+Cu reduced, not tubular for most of its length (Fig. 1B). (RS+M)a vein of forewing present (Fig. 1B). First metasomal tergum (T1) not greatly narrowed basally, i.e., widely attached to propodeum (Fig. 1D).

Biology. Parasitoids of adult Curculionidae (Jackson 1920; Aeschlimann 1980).

Diversity. There are three species described, one of which occurs in the Nearctic. There are likely a few undescribed species.

Distribution. Holarctic and Oriental realms.

Publications. Stigenberg and van Achterberg (2016) reviewed the genus.

Aridelus Marshall, 1887

Diagnosis. Shape of second submarginal cell (SSC) of forewing unique (Fig. 2C). Mesosoma covered with coarse honey-combed, areolate sculpture (Figs 2B, E). First metasomal segment narrow and elongate (Fig. 2E).

Biology. Parasitoids of late instar nymphs and adults of Pentatomidae.

Diversity. About 50 species are described worldwide, three Nearctic, and one Neotropical. Many more are undescribed. Presently there are 11 BINs (proxies for species) from Costa Rica on BOLD (Oct. 21, 2024) suggesting that there are around 100 Neotropical species.

Distribution. Cosmopolitan, in the New World from Canada to Argentina.

Publications. Papp (1965) provided a key to species.

Betelgeuse Shaw, 1989

Diagnosis. Mesosoma and head entirely coarsely rugose to rugose-punctate (Figs 3A, B, D) . Basal flagellomeres of female antenna serrate along outer margin. Flagellum with 13 flagellomeres. Scape (SC) about 5x longer than wide (Fig. 3D). Basal flagellomere (F) about 8 times longer than wide (Fig. 3D). Forewing venation unique (Fig. 3E). Male unknown.

Biology. Unknown.

Diversity. Three described species, perhaps several more undescribed.

Distribution. Neotropical (Mexico).

Publications. Shaw (1989) erected the genus and Shaw (2002) added two species and provided a key to species.

Bracteodes de Saeger, 1946

Diagnosis. Notauli present and distinct (Fig. 4D). Tarsal claws cleft (couplet 32A). Forewing vein M+Cu reduced, mostly or entirely not tubular (Fig. 4C). (RS+M)a vein of forewing absent (Fig. 4C). Scape (SC) length is less than 2.5 times width (Fig. 4B).

Biology. The Asian species B. ceranae is a parasitoid of the Asian honeybee, Apis cerana Fabricius (You and Zhou, 1991).

Diversity. Two described species one from Africa and the other from China. Shaw reported an undescribed species from the southwestern USA and Mexico in the Euphorinae chapter in the Manual of New World Braconidae (Shaw, 1997a). There is a Costa Rican specimen and a Colombian specimen (Fig. 4) in the Hymenoptera Institute collection.

Distribution. Afrotropical, Oriental, Nearctic, Neotropical (southwestern USA to Colombia).

Publications. None of interest to the New World fauna except the details mentioned in Shaw (1997a).

Centistes Haliday, 1835 (Fig. 5)

Diagnosis. First metasomal segment not greatly narrowed basally (Fig. 5C). Tarsal claws simple. Forewing vein M+Cu reduced, mostly or entirely not tubular (Figs 5D, E). Vein M absent as a tubular vein or tubular portion present as a very short stub (Figs 5D, E). Vein (RS+M)a variable, usually complete but varying from complete (Fig. 5D), to present as a stub apically (Fig. 5E), to completely absent.

Biology. Parasitoids of adult beetles, especially Curculionidae, Chrysomelidae, and Carabidae (Shaw, 1995).

Diversity. About 70 species are described worldwide and approximately nine in the New World. There are 26 BINs (proxies for species) in BOLD from Costa Rica (Oct. 13, 2024) suggesting that there are more than 200 hundred Neotropical species.

Distribution. Cosmopolitan with many undescribed Neotropical species.

Publications. Aguirre et al. (2017) revised the Costa Rican fauna, described 23 new species and provided a key to all Neotropical species.

Note. Members of the subgenus Syrrhizus Foerster have forewing (RS+M)a vein reduced (Fig. 5E) or absent.

Centistina Enderlein, 1912

Diagnosis. Scape 4 or more times longer than wide (Fig. 6D). Clypeus (C) relatively wide; scape (SC) relatively thin compared to Dinocampus (Fig. 6D). Antenna with many more than 8 flagellomeres. Forewing vein M+Cu complete and tubular (Fig. 6B). (RS+M)a vein of forewing present (Fig. 6B). Propodeum (PP) rounded in lateral view (Fig. 6A).

Biology. Unknown

Diversity. Six described species, and few are undescribed.

Distribution. Afrotropical, Neotropical, and southwestern Nearctic. Only two species are described from the New World, both are from Costa Rica.

Publications. Van Achterberg and Shaw (2000) described the two Costa Rican species.

Note. Eodinocampus Belokobylskij is a junior synonym (Belokobylskij, 2001).

Centistoides van Achterberg, 1992

Diagnosis. Dorsope absent. Maxillary palp with 3 segments; labial palp with 1 segment. Female hypopygium deeply incised medially. Forewing vein 2M sclerotized and present as a short but distinct branch (Fig. 7A). Forewing 3RS fully developed (Fig. 7A). First metasomal tergum not greatly constricted basally, almost as wide basally as apically (Figs 7G, 8G).

Biology. Unknown

Diversity. Two described species, undoubtedly a few undescribed species exist.

Distribution. Neotropical, only known from Surinam and Brazil.

Publications. Van Achterberg (1992a) erected the genus. Almeida and Penteado-Dias (2018) described the Brazilian species and distinguished it from the Surinam species.

Chrysopophthorus Goidanich, 1948

Diagnosis. Forewing r-m present, thus second submarginal cell closed (Fig. 9B). Mesosoma without honey-combed or areolate sculpture except on propodeum. Mesoscutum punctate and with distinct notauli (Fig. 9D). First metasomal segment as long as or longer than remainder of metasoma (Fig. 9D).

Biology. Parasitoids of adult Chrysopidae.

Diversity. Eight described species, one Nearctic and three Neotropical.

Distribution. Cosmopolitan.

Publications. Mason (1964) provided a key to the New World species. Van Achterberg (1994) revised the Palearctic species and summarized what is known of their biology.

Cosmophorus Ratzeburg, 1848

Diagnosis. Antennae each inserted on large protuberances (Fig. 10E). Labrum (L) large and occupying the large space between mandibles and clypeus (Fig. 10D). RS not quite reaching the wing margin (Fig.10A).

Biology. Parasitoids of adult Scolytinae (Curculionidae) (Loan and Matthews, 1973).

Diversity. 33 described species including five Nearctic species. None of the Neotropical species is described.

Distribution. Cosmopolitan.

Publications. The Nearctic species were most recently treated by Loan and Matthews (1973).

Cryptoxilos Viereck, 1911

Diagnosis. Eyes converging ventrally (Fig. 11E). Wing venation reduced with the m-cu crossvein absent (Fig. 11D).

Biology. Parasitoids of adult Scolytinae (Curculionidae) (Deyrup, 1981).

Diversity. Eight described species, including three from the Nearctic and one from the Neotropical realm. A small number undoubtedly remain undescribed.

Distribution. All realms except Afrotropical and Australian.

Publications. Deyrup (1981) gives a thorough description of the biology of C. lymantori.

Dinocampus Foerster, 1863

Diagnosis. Scape more than 2.5 x longer than wide (Fig. 12D). Labial palp with 2 segments. Distance from stigma (S) to RS is much less than half the distance from the stigma to the apex of the wing, i.e., RS ending far from the wing margin (Fig. 12C).

Biology. Parasitoids of adult Coccinellidae. A symbiotic virus is correlated with the manipulation of host behavior (Dheilly et al., 2015). Records for Curculionidae as hosts almost certainly refer to Perilitus species and not species that are now assigned to Dinocampus.

Diversity: There is one species described, and it may be the only one in existence.

Distribution. Cosmopolitan.

Publications. Dheilly et al. (2015) give a interesting summary of biology.

Ecclitura Kokujev, 1902 (Fig. 13)

Diagnosis. Scape more about 5 x longer than wide (Fig. 13C). Forewing vein (RS+M)a absent (Fig. 13D). Face narrow, i.e., the shortest distance between eyes is shorter than one eye width in anterior view (Fig. 13C).

Biology. Unknown.

Diversity: Three described species. Two from the Palearctic and one from Brazil. The few Nearctic species are not described.

Distribution. Holarctic, Neotropical.

Publications. De Almeida et al. (2019) described the Brazilian species.

Elasmosoma Ruthe, 1858

Diagnosis. The forewing venation of Elasmosoma (Fig. 14D) and Neoneurus are similar and unique amongst Euphorinae and indeed Hymenoptera. The two genera may be distinguished with a number of characters including the forewing of Elasmosoma having RS desclerotized or absent apically, usually indicated apically only by spectral venation (Fig. 14D).

Biology. Parasitoids of adult formicine ants (Poinar, 2004). Gómez Durán and Achterberg (2011) described the oviposition behavior and included a link to a film clip showing this (https://www.youtube.com/watch?v=GYGdEoaMYWs).

Diversity: 19 described species, six of which are Nearctic. There are 14 Nearctic BINs (proxies for species) in BOLD (Oct. 21, 2024) suggesting that there are likely more than 30 Nearctic species.

Distribution. Holarctic and northern Oriental.

Publications. Shaw (2007) provided a key to the Nearctic species.

Note. Stigenberg et al. (2015) showed that Neoneurini (Elasmosoma and Neoneurus) belong in the Euphorinae. Previously the tribe had subfamily status, Neoneurinae (Shaw, 1997a).

Holdawayella Loan, 1967

Diagnosis. The forewing venation is unique (Fig. 15B).

Biology. Parasitoids of late instar nymphs and adults of Tingidae.

Diversity: Two described Nearctic species, and at least one undescribed Neotropical species.

Distribution. Nearctic and Neotropical.

Publications. Loan et al. (1971) distinguished the two Nearctic species. Stigenberg et al. (2015) synonymized Ussurarideles Tobias and Belokobylskij with Holdawayella, however, van Achterberg and Soethof (2023) reinstated the genus. Since the two genera appear to be sister taxa this is simply a subjective decision.

Leiophron Nees, 1816

Diagnosis. Very similar to Peristenus. Basal cell (BC) of forewing often mostly or entirely glabrous (90%) (Figs 16B, C). First metasomal segment with tergum and sternum entirely separate, not fused ventrally at the base of the segment (Fig. 16F, couplet 34A), or fused throughout entire length (couplet 34AA). RS vein of forewing ending nearer stigma (S) than apex of wing and (RS+M)a vein of forewing present (Figs 16B, C, G). In specimens formerly placed in Euphoriella Ashmead (now considered a subgenus) the RS vein of the forewing is mostly absent and usually present only as a small stub on the wing margin (Fig. 16G). M+Cu vein of forewing mostly or entirely weak and non-tubular (Figs 16B, C, G). None of these characteristics will separate all species from Peristenus.

Biology. Parasitoids of late instar nymphs and adults of Hemiptera (Miridae and Lygaeidae) and Psocodea (Psocidae). The early instar nymph of the host is parasitized, and the mature larva emerges from the mature host nymph or adult (Zhang et al., 2018).

Diversity. Over 200 described species, about 70 in the Nearctic and a handful in the neotropics. There are 125 BINs (proxies for species) from Costa Rica on BOLD (March 28. 2025) suggesting that there are more than 1,000 undescribed species in the New World.

Distribution. Cosmopolitan.

Publications. Goulet and Mason (2006) reviewed the species attacking the Lygus bug. Zhang et al. (2018) redefined the limits of the genus.

Notes. Stigenberg et al. (2015) synonymized Euphoriella with Leiophron and it is recognized here as a subgenus. Zhang et al. (2018) synonymized Mama Belokobylskij with Leiophron.

Litostolus van Achterberg, 1985

Diagnosis. Distance from stigma to RS is much greater than half the distance from stigma to the apex of the wing, i.e., RS ending near wing margin (Fig. 17C). Forewing vein 2M long, not simply as a stub (Fig. 17C). Forewing vein M+Cu complete and tubular (Fig. 17C). Forewing crossvein m-cu complete (Fig. 17C). (RS+M)a vein of forewing present (Fig. 17C). Forewing second submarginal cell open, not closed or only partially closed distally (Fig. 17C). First metasomal tergum much wider apically than at base (Fig. 17E). Propodeum lacking projections laterally, weakly rounded or flat (Fig. 17A).

Biology. Unknown.

Diversity. Only one species is described occurring in USA and Canada. There are probably 20 or more undescribed New World species. 14 BINs are presently represented in BOLD (Oct. 14, 2024).

Distribution. Restricted to the New World (Canada to Brazil).

Publications. Van Achterberg (1985) described the sole species.

Marshiella Shaw, 1985

Diagnosis. Scape length is 3-3.5 times scape width. Female with setose pads on underside of basal flagellomeres (Fig. 18B). Males do not have the highly modified flagellomeres, but the scape (SC) is 3 times longer than wide (Fig. 19) thus distinguishing them from Microctonus and Townesilitus.

Biology. Reared from Anthicidae (Coleoptera) (Gornitz, 1937; Smith 1953).

Diversity. 10 described species, perhaps that many or more undescribed.

Distribution. Holarctic, Oriental, Neotropical (Canada to Brazil).

Publications. Shaw and Marsh (2000) revised the genus, described three new species, and provided a key to New World species. De Almeida et al. (2019) described a new species from Brazil. Amat et al. (2023) described a new species from China and included a key to the world species.

Note: A male specimen (Fig. 19) is recorded here for the first time. It was identified using COI barcode data on BOLD. The Sample ID on BOLD is BIOUG70880-A09.

Meteorus Haliday, 1835

Diagnosis. Forewing second submarginal cell present and 4-sided (Fig. 20C). Basal segment of metasoma usually more than 2x wider apically than basally (Fig. 20E). Hind wing vein RS straight (Fig. 20C) or bending towards anterior wing margin

Biology. Primarily endoparasitoids larval Lepidoptera (caterpillars), and occasionally larvae of Coleoptera.

Diversity. Over 300 described species, about 40 in the Nearctic and 70 in the Neotropics. Hundreds more species remain undescribed. Presently (Oct. 21, 2024) there are 101 BINs (proxies for species) in BOLD from Costa Rica alone.

Distribution. Cosmopolitan.

Publications. The Nearctic species have not been revised since Muesebeck’s (1923) treatment. Nearctic species have been published in scattered publications since then. Aguirre et al. (2015) summarized the described Neotropical species, added 11 new species, and included a key to species.

Microctonus Wesmael, 1835

Diagnosis. First metasomal segment greatly constricted basally and lacking anterior dorsolateral pits (Fig. 21E). Forewing vein M+Cu tube-shaped and complete (Fig. 21C). (RS+M)a vein of forewing absent (Fig. 21C). Scape (SC) length less than 2.5 times width (Fig. 21B).

Biology. Endoparasitoids of adult and sometimes larval beetles, especially Curculionidae, Chrysomelidae, and Carabidae.

Diversity. There are about 40 described species, hundreds more are undescribed. For example, presently (Oct. 12, 2024) there are 73 BINs (proxies for species) in BOLD from Costa Rica alone.

Distribution. Cosmopolitan.

Publications. Pucci (2013) revised the Canadian and USA species but most species in this region remain undescribed.

Note. Stigenberg et al. (2015) showed that Microctonus is nested within Perilitus but suggested that generic status be retained pending further phylogenetic research. Other authors such as van Achterberg et al. (2000) and Belokobylskij (2000b) have treated Microctonus as a subgenus of Perilitus.

Myiocephalus Marshall, 1898

Diagnosis. Head triangular in frontal view; eyes bulging, and head much wider than long in dorsal view (Fig. 22D). First metasomal segment greatly narrowed basally (Fig. 21B). Tarsal claws simple. Forewing crossvein m-cu present (Fig. 22C). Forewing vein RS complete to wing margin (Fig. 22C). Forewing vein M+Cu reduced, mostly or entirely not tubular (Fig. 22C). (RS+M)a vein of forewing absent (Fig. 22C). Forewing second submarginal cell open (Fig. 22C). Scape (SC) length is less than 2.5 times the scape width (Fig. 22D).

Biology. Associated with ants, but not reared (Donisthorpe, 1927).

Diversity. Five described species, several undescribed species occur in the southwestern USA and Mexico. There are 37 sequences and six BINs (proxies for species) in BOLD (Oct. 18, 2024). Three are from Finland and three from Canada; none is shared between the Old and New World. Canada and Finland are the only two Holarctic countries with extensive, public barcodes on BOLD for this group.

Distribution. Holarctic, Oriental, and Central American (Mexico).

Publications. Li et al. (2020) revised the world’s species.

Note. Foissner and van Achterberg (1997) showed that the genus name Loxocephalus Foerster was preoccupied, therefore the correct name for the genus is Myiocephalus.

Neoneurus Haliday, 1838

Diagnosis. The forewing venation of Elasmosoma and Neoneurus are similar, and both are unique. The two genera may be distinguished with several characters including the forewing of Neoneurus having RS sclerotized and present apically (Fig. 23B).

Biology. Endoparasitoids of adult ants of the genus Formica. Gómez Durán and van Achterberg (2011) document the oviposition behavior of three genera of Neoneurini, including Neoneurus. They include links to film clips of the behaviour which can be viewed on YouTube (https://www.youtube.com/watch?v=GYGdEoaMYWs).

Diversity. Sixteen species are described, seven in the Nearctic. There are 10 BINs (proxies for species) from Canada and the USA in BOLD (Oct. 21, 2024) suggesting that there are at least twice that number of species in the Nearctic.

Distribution. Holarctic.

Publications. Shaw (1992) revised the Nearctic species. Stigenberg et al. (2015) showed that Neoneurini (Elasmosoma and Neoneurus) belong in the Euphorinae. Previously the tribe had subfamily status, Neoneurinae (Shaw, 1997a).

Orionis Shaw, 1987

Diagnosis. First metasomal segment constricted near base and 5 or more times longer than apical width (Fig. 24A). Scape (SC) length is less than 2.5 times width (Fig. 24B). Forewing vein M+Cu complete and tubular (Fig. 24C). (RS+M)a vein of forewing complete. Second submarginal cell open, not closed apically (Fig. 24C).

Biology. Unknown; however, a European species has been photographed attacking an adult earwig (Dermaptera) (Bendixen and Shaw, 2024).

Diversity. Ten described species, four of which are Neotropical, not a species-rich genus but undescribed species remain.

Distribution. Neotropical, Palearctic, and Oriental.

Publications. Bortoni et al. (2016) revised the Neotropical species and provided a key. Broad and Stigenberg (2021) revised the Old World species and provided a key. Gupta et al. (2024) described new species from India and included a key to the Old World species.

Perilitus Nees, 1819

Diagnosis. First metasomal segment greatly constricted basally and lacking dorsal pits (Fig. 25D). Forewing vein M+Cu present and tubular (though this does not show well in the overexposed image in Fig. 25C). (RS+M)a vein of forewing present (Fig. 25C). Scape (SC) length is less than 2.5 times width (Fig. 25B).

Biology. Endoparasitoids of adult and sometimes larval beetles, especially Curculionidae, Chrysomelidae, and Carabidae.

Diversity. About 140 species are described but only about 12 from the New World. Many more are undescribed.

Distribution. Cosmopolitan.

Publications. There are no treatments of the few described New World species.

Note. Stigenberg et al. (2015) showed that Microctonus is nested within Perilitus but chose to maintain it as a separate genus pending further phylogenetic study. Van Achterberg et al. (2000) and Belokobylskij (2000b) treated Microctonus as a subgenus of Perilitus.

Peristenus Foerster, 1863

Diagnosis. Basal cell (BC) of forewing setose, though less so than other forewing cells (Fig. 26E, couplet 32B). Notauli present. Tergum of first metasomal segment fused or touching ventrally in anterior portion only (Fig. 26F). Forewing not banded (see Leiophron image Fig. 16B). RS vein of forewing ending nearer stigma than apex of wing (Fig. 26E). (RS+M)a vein of forewing present (Fig. 26E). None of these characteristics will separate all species from Leiophron.

Biology. Koinobiont endoparasitoids of late instar nymphs and adults of Miridae (Hemiptera). Early instar nymphs are parasitized, and the mature parasite larvae emerge from either the mature host nymphs or the adults (Zhang et al., 2018)

Diversity. About 140 described species, about 40 of these in the Nearctic. None is described from neotropics, but a few undescribed species occur there. Presently there are 42 BINs (proxies for species)  in BOLD (Oct. 18, 2024) from Canada implying that there should be more than 100 species in the Nearctic.

Distribution. Cosmopolitan, but concentrated in the Holarctic.

Publications. Goulet and Mason (2006) reviewed, and Zhang et al. (2017) revised the species attacking the Lygus bug. Zhang et al. (2018) redefined the limits of the genus. Loan (1974) revised the Nearctic species.

Plynops Shaw, 1996

Diagnosis. Face with projections below antennae (Fig. 27E). Forewing venation unique, similar or identical to Fig. 27C.

Biology. Unknown.

Diversity. 10 described species and about that number are probably undescribed.

Distribution. Restricted to the New World from southern Florida to Brazil.

Publications. Shaw (1996) erected the genus and described and keyed the 10 species.

Pygostolus Haliday, 1833

Diagnosis. Forewing 2M sclerotized and present as a short but distinct branch (Fig. 28C). (RS+M)a vein of forewing present (Fig. 28C). Tarsal claws simple. Females of most species have the venter (V) of the mesosoma flattened and setose (Fig. 28A). First metasomal segment only slightly constricted near base, almost as wide near base as it is apically (Fig. 28D). Apical flagellomere with a sharp terminal spine.

Biology. Usually endoparasitoids of adult Curculionidae, but larval or pupal stages may also be attacked with emergence always coming from the adult (van Achterberg, 1992b).

Diversity. Fourteen described (extant) species, four of which occur in the Nearctic. These same four also occur in the Palearctic (van Achterberg, 1992b).

Distribution. Holarctic and Neotropical including Chile.

Publications. Van Achterberg (1992b) revised the Holarctic species.

Ropalophorus Curtis, 1837

Diagnosis. The short antennae with 8 flagellomeres are unique among Euphorinae (Fig. 29C).

Biology. Endoparasitoids of adult Scolytidae (Yang et al., 2003).

Diversity. Four described species, perhaps a few undescribed.

Distribution. Holarctic, three species in China and one in the Nearctic (Shaw, 1985).

Publications. Yang et al. (2003) provided a key to the world species.

Note. R. wisconsinensis Shenefelt was synonymized with R. clavicornis (Wesmael) (Yang et al., 2023).

Spathicopis van Achterberg, 1977

Diagnosis. First metasomal segment with large basal dorsal pits (Fig. 30D). Forewing vein M+Cu reduced, mostly or entirely not tubular (Fig. 30C). (RS+M)a vein of forewing absent (Fig. 30C). Scape (SC) length is less than 2.5 times width (Fig. 30B).

Biology. Unknown.

Diversity. There is one species described, and several are undescribed.

Distribution. Oriental and Aftotropical (new record), Holarctic, U.S.A. and Canada in the Nearctic.

Publications. Van Achterberg (1977) described the sole species.

Streblocera Westwood, 1833

Diagnosis. The shortest distance between eyes is much longer than eye width in anterior view (Fig. 31B). Scape length more than 4 times scape width (Fig. 31B). (RS+M)a vein of forewing mostly or entirely absent (Fig. 31C). Propodeum rounded, lacking projections laterally (Fig. 31A). Female antennae of one undescribed Neotropical species and a described species from Brazil are raptorial (as in Fig. 31A) whereas all males and all other females in the New World have elongated scapes but otherwise unmodified antennae.

Biology. Endoparasitoids of adult Chrysomelidae, summarized in Chen and van Achterberg (1997).

Diversity. More than 100 described species worldwide, but few in the New World. There are four undescribed species from Costa Rica on BOLD (Nov. 7, 2024) suggesting that there are several dozen species in the Neotropics.

Distribution. Pantropical, Oriental, and Palearctic.

Publications. De Almeida et al. (2019) described a species from Brazil.

Notes. A species of Streblocera from Canada described by Walley and MacKay (1963) was transferred to Marshiella, M. pulvillicornis (Walley and Mackay) by Shaw (1985). Lecythodella is now considered a subgenus of Streblocera following Stigenberg et al. (2015).

Syntretus Foerster, 1863

Diagnosis. Notauli absent (Fig. 32D). Tarsal claws cleft. Forewing vein M+Cu reduced, mostly or entirely not tubular (Fig. 32C). (RS+M)a vein of forewing mostly or entirely absent (Fig. 32C).

Biology. Endoparasitoids of adult Ichneumonidae, the adults of several species of bees as well as Drosophila. Details are in Moore et al. (2024) who also summarize the biology of the genus. Folly et al. (2025) reported the presence of polydnavirus in nine European species of Syntretus.

Diversity. 62 described species, 7 in the Nearctic and 7 in the Neotropical region. There are 39 BINs (proxies for species) in BOLD from Costa Rica (Oct. 14, 2024). This implies that there may be several hundred species in the Neotropical region alone.

Distribution. Cosmopolitan.

Publications. Papp and Shaw (2000) revised the species of the subgenus Falcosyntretus Tobias from the New World with five new species and a key to species. Van Achterberg and Haeselbarth (2003) revised the Syntretus species of Europe, summarized the taxonomy and biology of the genus. There are no recent treatments of the Nearctic species except for that of Moore et al. (2024).

Note. Van Achterberg and Haeselbarth (2003) treated Falcosyntretus as a junior synonym of Syntretus.

Townesilitus Haeselbarth and Loan, 1983

Diagnosis. Very similar to Microctonus. Head circular in frontal view and eyes not bulging (Fig. 33D). First metasomal segment greatly narrowed basally (Fig. 33C). Tarsal claws simple. Forewing vein M+Cu mostly or entirely tubular (Fig. 33B). (RS+M)a vein of forewing absent (Fig. 33B). Scape (SC) length less than 2.5 times scape width (Fig. 33D). Propodeum not evenly areolate rugose. The presence of areolate rugose sculpture is variable, however there are carinae delimiting larger cells on the propodeum and these are not present in 90% of Microctonus species. Except for the last feature these states also diagnose members of Microctonus. Features to distinguish between these two genera that have been used in the past include: 1. Clypeus with blister-like sculpture on apical margin (barely discernable in Fig. 33D) or clypeus with a flattened apical margin. These states are found in only a few New World species and are difficult to see but work well when present. 2. First tergite in front of spiracles closed ventrally, tube-shaped and rounded laterally. This condition is also found in many New World species of Microctonus.

Biology. Endoparasitoids of adult flea beetles (Alticini: Chrysomelidae) (Stigenberg, 2017).

Diversity. 12 described species, including three Nearctic species. Perhaps a dozen more undescribed Nearctic species. Presently in BOLD (Oct. 19, 2024) there are four BINs (proxies for species) from Costa Rica and six from Canada.

Distribution. Holarctic, Neotropical and Oriental.

Publications. No general treatments for the Nearctic region. Some species were originally described under Microctonus.

Note. According to co-author van Achterberg, Gamosecus Provancher, 1880 (type species: G. mellinus Provancher, 1880) either belongs to the large group of Nearctic Microctonus with the basal half of the first tergum tube-shaped or to Townesilitus. In the latter case Gamosecus is the senior name for what is now called Townesilitus. The drawing in Fig. 33E shows the “lips” on the margin of the clypeus typical of some species of Townesilitus. Unfortunately, the identification of the specimen is questionable and the type specimen of G. mellinus needs to be checked.

Wesmaelia Foerster, 1863

Diagnosis. First metasomal segment is exceptionally long and thin throughout its length (Fig. 34D). Forewing second submarginal cell open, not closed apically (Fig. 34C). RS vein of forewing ending well before wing apex (Fig. 34C).

Biology. Endoparasitoids of late instar nymphs and adults of Nabidae (Hendrick and Stern, 1970).

Diversity. About 12 species are described. One Nearctic and one Neotropical species are described. There may be about a dozen undescribed species.

Distribution. Cosmopolitan, except Australian and African realms.

Publications. Shaw (1997b) described a species from Costa Rica and provided a key to the two New World species.

Yanayacu Zhang and Chen, 2015

Diagnosis. Basal flagellomere about 5x longer than wide (Fig. 35B). Propodeum with projections laterally (Fig. 35A).

Biology. Unknown.

Diversity. Only known by the type species. A few more are expected to be discovered.

Distribution. Neotropical.

Publications. Shaw (2012) proposed the genus Napo and described the sole species. The mating and defensive behavior of Yanayacu townsendi Shaw (as Napo townsendi) was explored by Robinson et al. (2015)

Note. Zhang and Chen (2015) showed that the generic name Napo was preoccupied by a deltocephaline leafhopper genus and changed the name of this braconid genus to Yanayacu.

Zele Curtis, 1832

Diagnosis. Forewing second submarginal cell (SSC) 4-sided (Fig. 36B). Hind wing vein RS bending away from anterior wing margin (Fig. 36B).

Biology. Endoparasitoids of lepidopteran larvae.

Diversity. About 30 species are described, about 13 in the New World. A few dozen may be undescribed.

Distribution. Cosmopolitan, except Australia.

Publications. Muesebeck (1923) revised the USA and Canadian species under Meteorus. Van Achterberg (1979) revised the world species, and added species (van Achterberg, 1984).

Note. Stigenberg et al. (2015) and previous authors showed that Zele is nested within Meteorus and may not deserve separate status.