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Trematopygus Holmgren, 1857: 179. Type species: Trematopygus ruficornis Holmgren. Subsequent designation by Viereck (1912: 177).
Amorphognathon Foerster, 1869: 203. Type species: Tryphon melanocerus Gravenhorst, 1829. Included by Kriechbaumer (1897: 185). Monobasic. Synonymized by Roman (1925).
Rhigelus Foerster, 1869: 208. Type species: Trematopygus kriechbaumeri Thomson [= melanocerus Gravenhorst]. Subsequent designation by Perkins (1962: 449). Synonymized by Perkins (1962: 449).
Aselasma Foerster, 1869: 209. Type species: Tryphon vellicans Gravenhorst. Subsequent designation by Townes et al. (1965: 242). Synonymized by Townes et al. (1965: 242)
Campoporus Foerster, 1869: 210. Type species: Ichneumon dictator Thunberg, 1822 [= nigricornis Holmgren]. Subsequent designation by Perkins (1962: 412). Synonymized by Perkins (1962: 412).
Volucris Davis, 1897: 267. Type species: Tryphon semirufus Cresson. Included by Davis, 1898. Viereck (1914) attributes the synonymy to Roman (1909).

Holmgren’s work is sometimes cited with different dates, most notably 1855.

The Palaearctic species of Trematopygus were treated by Hinz (1986) (the date on reprints is given as 30 December 1985, but the paper was apparently published early in 1986). The genus is Holarctic, but only T. semirufus has thus far been described from the Nearctic.

The following were included as valid species by Yu et al. (2012):

Trematopygus apertor Hinz, 1986
Trematopygus bicolor Rudow, 1883
Trematopygus chabarovski Hinz, 1986
Trematopygus dubitor Hinz, 1982
Trematopygus helleni Hinz, 1982
Trematopygus hemikrikos Sheng and Su, 1996
_Trematopygus horvathi (Kiss, 1926)
Trematopygus irkutski Hinz, 1986
Trematopygus koreator Hinz, 1986
Trematopygus lethierryi Thomson, 1894
Trematopygus melanocerus (Gravenhorst, 1829)
Trematopygus micrator Hinz, 1986
Trematopygus nigricornis Holmgren, 1857
Trematopygus rufator Hinz, 1986
Trematopygus ruficornis (Zetterstedt, 1838)
Trematopygus rufiventris Rudow, 1883
Trematopygus semirufus (Cresson, 1864)
Trematopygus spiniger Hinz, 1976
Trematopygus terebrator Hinz, 1986
Trematopygus triangulator Aubert, 1981
Trematopygus vellicans (Gravenhorst, 1829)
Trematopygus vellicator Hinz, 1986

A large number of ctenopelmatine species, currently placed in other genera, were originally described in Trematopygus prior to its redefinition by Townes (1970) and others.

Trematopygus is characterized by the distinctly flattened second trochanter (= the trochantellus) (Fig. 1). In all other pionine genera, the trochantellus is rounded beneath, as is typical for ichneumonids in general. Otherwise, the species of Trematopygus closely resemble those in Glyptorhaestus. One of the major characters used in keys to separate these two genera [placement of the dorsal end of the epicnemial carina at ( Glyptorhaestus ) or removed from ( Trematopygus ) the anterior margin of the mesopleuron] is not entirely reliable.

Clypeus with surface usually polished, sparsely punctate, and sparsely setose (Figs 4, 5); ventral margin varying from weakly to distinctly convex, the margin blunt (Fig. 4); epistomal sulcus impressed throughout, weak medially in some species (Fig. 5), very strongly impressed in others; clypeus in profile weakly protruding (Fig. 7). Face densely granular-punctate, frons and vertex often similarly sculptured, though vertex slightly less so in some species (Fig. 8); inner eye margins straight to weakly converging (Figs 4, 5). Malar space absent or nearly so (Figs 4, 5). Mandible (Fig. 6) strongly curved (Fig. 9), narrowing gradually from base to apex; dorsal tooth varying among species from equal to distinctly longer than ventral tooth; basal, transverse impression absent; ventral margin distinctly carinate. Ocelli small, distance from lateral ocellus to eye usually at least twice diameter of lateral ocellus (Fig. 8). Maxillary palp shorter than height of head, in some species only half head height; female antenna slightly to distinctly shorter than body. Hypostomal carina meeting occipital carina at base of mandible (Fig. 9); occipital carina complete. Epomia absent or very indistinct. Epicnemial carina usually not reaching anterior margin of mesopleuron (Figs. 10, 11), rarely appearing to do so. Notaulus usually absent (Fig. 10) or nearly so, rarely impressed on anterior declivity, extending posteriorly to level of tegula as barely detectable impressions. Groove between propodeum and metapleuron u-shaped, readily visible in lateral view; broad, u-shaped groove mid-dorsally between propodeum and metanotum also readily visible in lateral view; pleural carina usually well-developed, complete, but sometimes obscured by heavy sculpture; median and lateral longitudinal carinae usually well developed and complete; posterior transverse carina complete, anterior transverse variable, rarely complete, with costula and/or median portion absent, areola thus sometimes present and sometimes confluent with median basal area; petiolar area always well -defined, without median longitudinal carina. Hind femur moderately stout (Fig. 2) to somewhat more slender (Fig. 3); hind trochantellus (= second trochanter) flattened ventrally, the flattened portion at least weakly carinate on its lateral margin and distinctly carinate apically; apical margin of mid tibia often expanded into a distinct tooth similar to that of fore leg, though more rounded and less distinct in some species; apical comb on posterior side of hind tibia absent; posterior hind tibial spur short (Fig. 3), about 7x longer than maximum width at base; tarsal claws in at least some species pectinate at extreme base (difficult to see), pectination apparently absent in other species. Fore wing areolet absent in the five species examined, though Townes (1970) indicated that it is sometimes present; stigma relatively narrow (Fig. 14), Rs+2r either arising near basal 0.3-0.4 of stigma or near midpoint. Hind wing (Fig. 14) with first abscissa of CU1 distinctly longer than 1cu-a. T1 (Figs 3, 15-18) short, broad, gradually expanded from base to apex, never parallel-sided (Fig. 15); weakly decurved to essentially straight in profile; dorsal carinae distinct but variable in length among species: extending nearly full length in some species, but only covering basal 0.5 in others; basal depression at dorsal tendon attachment broad, obvious; dorsal-lateral carina complete along full length of T1 in some species, partially obscured by heavy sculpture, especially posteriorly, in others; glymma present as a basal impression: broad in some species (Fig. 17), narrower in others (Fig. 16). S1 short, 0.35-0.4 times length of T1, not extending to level of spiracle. T2 thyridium absent (Fig. 19), T2 usually sculptured, minimally densely punctate; laterotergites of T2 and T3 separated by creases from median tergite. Ovipositor and sheath (Figs 20-21) narrow, upcurved; ovipositor relatively shorter than in Pion, abruptly becoming needle-like apically from distinctly swollen base (Fig. 21); without dorsal, subapical notch.

The above description is modified from Townes (1970) and based on material in the Texas A&M University Collection, including at least one undescribed species from Texas.

The following hosts and references for those hosts records were taken from Yu (2005):

Amauronematus fallax (Roman 1931; Hinz 1961)
Arge rosae (Rudow 1919)
Athalia spinarum (Rudow 1919)
Caliroa cerasi (Crushman 1915)
Croesus latipes (Rudow 1919)
Croesus septentrionalis (Zirngiebl 1961; Bridgman 1882; Brischke 1878; Jacobs and Tosquinet 1892; Rudow 1919; Boeve 1991)
Croesus varus (Ozols 1961; Boeve 1991)
Dolerus anthracinus (Hinz 1976, )
Dolerus eglanteriae (Rudow 1919)
Dolerus genucinctus (Hinz 1961, 1986)
Dolerus gessneri (Hinz 1961, 1986)
Dolerus gonager (Ozols 1961; Brischke 1871, 1878)
Dolerus labiosus (Hinz 1982)
Dolerus pratensis (Ozols 1961)
Dolerus pratorum (Gyorfi 1947)
Dolerus nigratus (Hinz 1986)
Dolerus vestigialis (Hinz 1961, 1986; Aubert 2000)
Eriocampa ovata (Rudow 1919)
Euura atra (Aubert 2000)
Hemichroa alni (Rudow 1919)
Heterarthrus microcephalus (Zirngiebl 1961)
Nematus aethiops (Brischke 1878; Jacobs and Tosquinet 1892; Rudow 1919)
Nematus cognata (Hellen 1961)
Nematus ferrugineus (Ozols 1961)
Nematus hortensis (Rudow 1919)
Nematus palliatus (Brischke 1888)
Nematus salicis (Martinek 1958)
Neodiprion sertifer (Dalla Torre 1902; Rudow 1919)
Periclista albida (Hinz 1980)
Periclista albipennis (Aubert 2000)
Periclista melanocephala (Giraud 1872)
Periclista pubescens (Giraud 1872; Rudow 1917, 1919; Hinz 1961; Brischke 1878; Hinz and Horstmann 1998)
Platycheirus erraticus (Carlson 1979)
Pristiphora alnivora (Brischke 1871, 1878
Pristiphora erichsonii (Pschorn-Walcher and Zinnert 1971)
Pristiphora ruficornis (Idar 1983)
Sphaerophoria philanthus (Carlson 1979)
Strongylogaster macula (Bauer 1958)
Trichiocampus viminalis (Gyorfi 1947, 1963)

This page was assembled by Bob Wharton as part of a larger collaborative effort on the genera of Ctenopelmatinae. Page last updated April, 2015.

This work would not have been possible without the groundwork provided by Ian Gauld’s study of the Australian and Costa Rican faunas, and we are particularly grateful for his assistance in many aspects of this study. We also thank the following curators for extended loans of the material used for this study: David Wahl of the American Entomological Institute and Andy Bennett of the Canadian National Collection. We also thank David Wahl for useful feedback throughout our study and particularly Dave Karlsson for sending valuable material from the Swedish Malaise Trap Survey (trap 10, collection event 408; trap 50, collection event 1222; trap 37, collection event 831). Matt Yoder provided considerable assistance with databasing issues, and our use of PURLs (http://purl.oclc.org) in this regard follows the example of their use in publications by Norm Johnson. Heather Cummins, Andrea Walker, Patricia Mullins, Caitlin Nessner, Amanda Ladigo, Jacques Dubois, and Cheryl Hyde graciously assisted with image processing, formatting, and literature retrieval. This study was supported by the National Science Foundation’s PEET program under Grant No. DEB 0328922 and associated REU supplement #s DEB 0616851, 0723663, 0923134, and 1026618.

This material is based upon work at Texas A&M University supported by the National Science Foundation under Grant Number DEB 0328922 with REU supplements DEB 0723663 and 0923134. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.