Acraspis quercushirta (agamic)

Acraspis quercushirta (sexgen)

Acraspis villosa (agamic)

Acraspis villosa (sexgen)

Amphibolips spinosa (agamic)

Amphibolips spinosa (sexgen)

Andricus balanaspis (sexgen)

Andricus balanaspis (agamic)

Antron quercusnubila (sexgen)

Antron quercusnubila (agamic)

Bassettia flavipes (sexgen)

Bassettia flavipes (agamic)

Bassettia pallida (sexgen)

Bassettia pallida (agamic)

Melikaiella tumifica (agamic)

Melikaiella tumifica (sexgen)

Neuroterus floccosus (sexgen)

Neuroterus floccosus (agamic)

Neuroterus niger (agamic)

Neuroterus niger (sexgen)

Acraspis gemula (sexgen)

Philonix fulvicollis (sexgen)

Philonix fulvicollis (agamic)

Phylloteras poculum (agamic)

Phylloteras poculum (sexgen)

Sphaeroteras carolina (sexgen)

Sphaeroteras carolina (agamic)

Acraspis quercushirta (Bassett, 1864)

[Many synonyms; see table above]

Biology. See Bassett (1864), Weld (1922a, 1926), and Kinsey (1930, 1936) for the biology of the asexual generation. Asexual generation galls (Fig. 12) have been recorded on leaves of Q. chapmanii, Q. gambelii, Q. macrocarpa, Q. michauxii, and Q. montana. Adult females of the asexual generation emerged in Edmonton from late September to early November, with the peak occurring during the last half of October. Bassett (1864) noted that adult females of the asexual generation bore exit holes in their galls some time prior to emerging. This behaviour was observed in Edmonton as well, with females often remaining for days or weeks just inside emergence holes. Completion of emergence was often triggered by cooler temperatures. Leaves with galls have mostly fallen to the ground when the brachypterous females emerge in Edmonton, so they walk to a bur oak tree bole, climb it, and oviposit into bud scales, remaining active for up to 2–3 weeks, often at temperatures below freezing. 

Galls of the asexual generation appeared on leaves starting in late June or early July. 

Distribution. USA: Connecticut south to Virginia, Illinois, Michigan, Texas, Utah (Burks 1979), Colorado, New Mexico, Oklahoma (Kinsey 1930). Canada: Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick. Probably everywhere east of the Rocky Mountains in the USA and Canada where white oaks occur (Kinsey 1930) or have been introduced as urban trees (e.g., bur oak in Alberta).

Acraspis quercushirta (Bassett, 1864), sexual generation

[Many synonyms given but all are taken to apply to the agamic generation; see table on that page]

Gall (Fig. 13). Sexual galls develop in the innermost scales in apical and lateral buds, a brittle, thin-walled, seed-like, sub-ovoid cell approximately 2 mm long, tan or orange-brown when mature, with faint longitudinal striations and sparse, pale hairs. Galls form in the basal portion of the scale and often leave the scale apex intact, which extends as a flat flap beyond the gall. 

Biology. Galls of the sexual generation usually occur singly, but up to six galls were found around a single bud. Galls and inhabitants survived freezing in late April 2005 in Edmonton that destroyed new shoots on many bur oaks. Emergence typically occurs through holes chewed near gall apices. Empty galls can persist around bases of new shoots for weeks or months, but are easily detached as bud scales slough off during shoot maturation. Adults of the sexual generation emerged in Edmonton from late May to early June.

Distribution. USA: Connecticut south to Virginia, Illinois, Michigan, Texas, Utah (Burks 1979), Colorado, New Mexico, Oklahoma (Kinsey 1930). Canada: Alberta, Saskatchewan, Manitoba, Ontario, Quebec, New Brunswick. Probably everywhere east of the Rocky Mountains in the USA and Canada where white oaks occur (Kinsey 1930) or have been introduced as urban trees (e.g., bur oak in Alberta).

Acraspis villosa Gillette, 1888, sexual generation

Synonyms: Acraspis villosus Gillette (1888: 218), females and galls. Acraspis villosa corrected spelling by Dalla Torre (1893: 64); Philonix villosus combination by Felt (1906: 713); Philonix villosa combination by Beutenmueller (1909: 249); Cynips (Acraspis) villosa var. villosa combination by Kinsey (1930: 355). 

Kinsey (1930, 1936) described the asexual generation of six additional species within his “villosa” complex: Cynips (Acraspis) apache Kinsey, 1930 from Q. grisea and Q. arizonica; Cynips (Acraspis) calvescens Kinsey, 1930 from Q. gambelii; Cynips (Acraspis) consocians Kinsey, 1930 from Q. macrocarpa; Cynips (Acraspis) erutor Kinsey, 1936 from Q. repanda; Cynips (Acraspis) expletor Kinsey, 1936 from Q. oblongifolia; and Cynips (Acraspis) expositor Kinsey, 1930 from Q. grisea. Weld (1951) and Burks (1979) treated four of these species as varieties of A. villosa; hence Acraspis villosa var. apache (Kinsey), syn. nov., Acraspis villosa var. calvescens (Kinsey), syn. nov., Acraspis villosa var. consocians (Kinsey), syn. nov., and Acraspis villosa var. expositor (Kinsey), syn. nov. are all synonyms of A. villosa. Two species known only from Mexico are valid and treated as Cynips erutor Kinsey and C. expletor Kinsey (Pujade-Villar & Ferrer-Suay 2015).

Biology. See Weld (1926) and Kinsey (1930, 1936) for the biology of the asexual generation. Asexual galls (Fig. 27) from species in Kinsey’s (1936) “villosa” complex have been recorded on leaves of Q. alba, Q. arizonica, Q. gambelii, Q. grisea, Q. macrocarpa and Q. oblongifolia. Adult females of the asexual generation emerged (from galls collected in Manitoba but reared in Edmonton) during the second half of October and early November. Adults of the sexual generation emerged in Edmonton from late May to early June. Galls of the asexual generation appeared on leaves in Edmonton in July. 

Distribution. USA: New York, Michigan, Iowa, Kansas, Texas, Utah, Arizona (Burks 1979); Canada: Manitoba

Acraspis villosa Gillette, 1888, sexual generation

[Synonyms listed are for the agamic generation; see that page for details]

Gall (Fig. 28). The sexual galls are not apparently distinguishable from galls of the sexual generation of Acraspis quercushirta, described above. [Sexual galls develop in the innermost scales in apical and lateral buds, a brittle, thin-walled, seed-like, sub-ovoid cell approximately 2 mm long, tan or orange-brown when mature, with faint longitudinal striations and sparse, pale hairs. Galls form in the basal portion of the scale and often leave the scale apex intact, which extends as a flat flap beyond the gall.] 


Biology. See Weld (1926) and Kinsey (1930, 1936) for the biology of the asexual generation. Asexual galls (Fig. 27) from species in Kinsey’s (1936) “villosa” complex have been recorded on leaves of Q. alba, Q. arizonica, Q. gambelii, Q. grisea, Q. macrocarpa and Q. oblongifolia. Adult females of the asexual generation emerged (from galls collected in Manitoba but reared in Edmonton) during the second half of October and early November. Adults of the sexual generation emerged in Edmonton from late May to early June. Galls of the asexual generation appeared on leaves in Edmonton in July. 

Distribution. USA: New York, Michigan, Iowa, Kansas, Texas, Utah, Arizona (Burks 1979); Canada: Manitoba

Amphibolips spinosa Ashmead, 1887, sexual generation

Synonyms: Amphibolips spinosa Ashmead (1887: 141), females and galls. Amphibolips spinosus corrected spelling by Dalla Torre & Kieffer (1910: 591)

Biology. Alternate asexual and sexual generations are known. Asexual galls (Fig. 42) are ovate, about 10 mm long, in buds on Q. laurifolia and Q. myrtifolia. The sexual bud galls begin to develop in early May, mature in May-June, adults emerge in May through June. We recorded sexual galls on Q. myrtifolia, Q. laurifolia, Q. inopina and Q. incana. 

Distribution. USA: Florida, Highlands, Manatee, Martin, Walton, Liberty, Brevard Counties. We found this species also in North Carolina (Patsy Pond Area and Croatan National Forest, Carperet Co.).

Amphibolips spinosa Ashmead, 1887, sexual generation

Synonyms: Amphibolips spinosa Ashmead (1887: 141), females and galls. Amphibolips spinosus corrected spelling by Dalla Torre & Kieffer (1910: 591)

Diagnosis. The sexual galls resemble those of A. quercuscitriformis (Ashmead, 1881), but differ from them in having much thicker and harder walls, the surface of the gall is rough, and they are appreciably narrower, and turn dirty brown when mature; in contrast the galls of A. quercuscitriformis are much more fragile at maturity, with thinner walls, the surface of the gall is smooth and glabrous, are much broader in diameter, remain lemon-yellow after adult emergence. 

Gall (Fig. 43). Spindle-like bud galls, green and soft while young and growing, 20–25 mm in length, 5–7 mm in diameter. The surface is rough, not shiny, with pale spots, interior filled with dense radiating filaments that support the central larval cell. After the gall matures, it turns dirty brown, the walls are very hard and approximately 1 mm thick. 

Biology. Alternate asexual and sexual generations are known. Asexual galls (Fig. 42) are ovate, about 10 mm long, in buds on Q. laurifolia and Q. myrtifolia. The sexual bud galls begin to develop in early May, mature in May-June, adults emerge in May through June. We recorded sexual galls on Q. myrtifolia, Q. laurifolia, Q. inopina and Q. incana. 

Distribution. USA: Florida, Highlands, Manatee, Martin, Walton, Liberty, Brevard Counties. We found this species also in North Carolina (Patsy Pond Area and Croatan National Forest, Carperet Co.).

Andricus balanaspis (Weld, 1922), comb. nov., sexual generation

Synonyms: Callirhytis balanaspis Weld, 1922b: 22, female, gall.

Diagnosis. The sexual generation of A. balanaspis most closely resembles three species from Florida that also gall catkins, Callirhytis myrtifoliae (Beutenmueller, 1917) on Q. myrtifolia, Callirhytis quercusturnerii (Ashmead, 1881) on Q. nigra and Andricus cooki Melika, Nicholls & Stone, 2021 on Q. myrtifolia and Q. laurifolia. In C. myrtifoliae the clusters of catkin galls are smooth and shiny, without pubescence, while in A. balanaspis the catkin galls are covered with sparse white setae. In A. cooki, clusters of galls are dark green to purple with dense short pubescence, contain 10-20 individual galls tightly grouped together that cause shortening of the catkin axis; in A. balanaspis the galls are pale green with longer pubescence, and are scattered along a normal-length catkin. 

Gall (Figs 56–57). Sexual galls are aggregated on catkins, each rounded, to 3 mm in diameter, pale green with white pubescence. In sparse clusters, rarely singly, along axis of catkin; sometimes causing the catkin to curl but never stunting its development. 

Biology. Alternate asexual and sexual generations are known, inducing galls on red oaks in (Quercus section Lobatae). The asexual generation galls (Figs 58–60) have been found on acorns of Q. marilandica and Q. myrtifolia, mature in October, adults emerge in spring of the following year. To date, sexual catkin galls have only been recognised on Q. inopina and Q. myrtifolia, mature in April, adults emerge soon afterwards. 

Distribution. USA: Washington DC, Missouri, Arkansas, Texas, Virginia, Florida. 

The authors’ unpublished sequence data show that A. balanaspis is part of a clade of species galling red oaks whose sexual generations, where known, are on catkins and asexual generations, where known, are acorn galls. This clade includes species such as Callirhytis carmelensis Weld, 1922, A. cooki, C. myrtifoliae, A. fitpatricki Melika & Abrahamson, 2021 and C. balanacea Weld, 1944

Andricus balanaspis (Weld, 1922), comb. nov., sexual generation

Synonyms: Callirhytis balanaspis Weld, 1922b: 22, female, gall.

Biology. Alternate asexual and sexual generations are known, inducing galls on red oaks in (Quercus section Lobatae). The asexual generation galls (Figs 58–60) have been found on acorns of Q. marilandica and Q. myrtifolia, mature in October, adults emerge in spring of the following year. To date, sexual catkin galls have only been recognised on Q. inopina and Q. myrtifolia, mature in April, adults emerge soon afterwards. 

Distribution. USA: Washington DC, Missouri, Arkansas, Texas, Virginia, Florida. 

The authors’ unpublished sequence data show that A. balanaspis is part of a clade of species galling red oaks whose sexual generations, where known, are on catkins and asexual generations, where known, are acorn galls. This clade includes species such as Callirhytis carmelensis Weld, 1922, A. cooki, C. myrtifoliae, A. fitpatricki Melika & Abrahamson, 2021 and C. balanacea Weld, 1944

Antron quercusnubila (Bassett, 1881), sexual generation

[Synonyms are listed on the agamic gall page]

Material examined: 1 female and 2 males “USA, Arizona, Molino Basin campground, Santa Catalina Mtns. leg. 
J. Nicholls, 2008.04.09. Code AZ1875, spAZb9; ex Quercus oblongifolia”

Diagnosis: the bud galls of A. quercusnubila are oblong with long hairs.

Gall (Figs 80–81). The sexual generation develops in a small oblong bud gall, 5 mm long, 3 mm in diameter, pale green with white or pink pubescence, hairs several mm long. The gall develops on lenticel buds on stems or on the bark of larger branches. 

Biology. Asexual galls (Fig. 79) develop on leaves, sexual galls in lenticel buds; both generations on Q. arizonica, Q. rugosa and Q. oblongifolia. 

Distribution. USA: Arizona (Burks 1979).

Antron quercusnubila (Bassett, 1881), sexual generation

Synonyms: Cynips quercusnubila Bassett (1881b: 56), females and galls. Dryophanta nubila combination and corrected spelling by Mayr (1881); Dryophanta nubila combination by Ashmead (1885: 296); Diplolepis quercus-nubila combination by Dalla Torre and Kieffer (1910); Cynips nubila combination by Cresson (1923); Diplolepis nubila combination by Weld (1926); Cynips (Acraspis) nubila var. nubila combination by Kinsey (1930); Antron nubila combination by Weld (1951); Antron quercusnubila corrected spelling by Burks (1979). Kinsey (1930, 1936, 1938) included 10 additional species in his “nubila” complex, found on a range of Mexican oaks: Cynips (Acraspis) chica Kinsey 1936; Cynips (Acraspis) incompta (Kinsey, 1920); Cynips (Acraspis) nigricula Kinsey, 1936; Cynips (Acraspis) radialis Kinsey, 1936; Cynips (Acraspis) rufula Kinsey, 1936; Cynips (Acraspis) russa Kinsey, 1930; Cynips (Acraspis) subtincta Kinsey, 1936; Cynips (Acraspis) tincta Kinsey, 1936, Cynips (nubila) lanaris Kinsey, 1938 and Cynips (nubila) molucrum Kinsey, 1938. 

Cynips (Acraspis) russa Kinsey, 1930, syn. nov.. Kinsey (1930) originally used the species name Cynips nubila russa and mentioned that he found the female to be indistinguishable from the female of C. nubila. The galls are also identical to those of A. quercusnubila and the two taxa share the same host oaks (Q. arizonica, Q. oblongifolia) and geographic distribution (Arizona, Santa Catalina Mnt., from Tucson to Globe). Later, Kinsey (1936) put Cynips nubila russa into the genus Cynips subgenus Acraspis, nubila complex, named as Cynips (nubila) russa. Weld (1952a) treated it as Cynips nubila russa Kinsey. Weld (1960) in his Cynipid Galls of the Southwest listed only Antron nubila, and did not even mention A. russa. In Burks (1979) it is a valid species, Antron russum (Kinsey, 1930). The other nine species of Kinsey’s Cynips nubila complex, all occurring in Mexico, are considered valid species by Pujade-Villar & Ferrer-Suay (2015).

Biology. Asexual galls (Fig. 79) develop on leaves, sexual galls in lenticel buds; both generations on Q. arizonica, Q. rugosa and Q. oblongifolia. 

Distribution. USA: Arizona (Burks 1979).

Bassettia flavipes (Gillette, 1889), comb. nov., asexual generation

Synonyms: Neuroterus flavipes Gillette 1889: 281. Male, female and gall. Description reprinted by Gillette (1890: 21). Beutenmüller (1910: 136) suggested that this species should probably be placed in Callirhytis or Andricus rather than Neuroterus. Kinsey (1923: 136) agreed, and left this species unplaced in his revision of Neuroterus. Callirhytis flavipes (Gillette): combination by Weld (1926: 91). Melika & Abrahamson (2002: 168) considered this species should belong to Andricus, however, this transfer was made only informally, without following the ICZN requirements.

Biology. Sexual generation galls are multilocular, fleshy swellings along the leaf midrib or major lateral veins (Fig. 94) and are visible starting in mid- to late May in Edmonton. Adults emerged starting in late June or early July, and males tended to begin emerging earlier than females. Each emerging adult appeared to cut its own exit hole from the gall. Adult females of the sexual generation of B. flavipes oviposited into twig bark. We did not assess whether unmated females oviposited or produced viable eggs. Sexual generation galls have been recorded from Q. macrocarpa and Q. alba (Burks 1979, Weld 1926), and the authors additionally observed them on Q. ⨯ bebbiana (Q. alba x Q. macrocarpa) and Q. ⨯ schuettei (Q. bicolor x Q. macrocarpa) at the Jardin Botanique de Montreal in August 2007.

Distribution. USA: Illinois, Indiana, Iowa, Minnesota, North Dakota, Virginia; Canada: Alberta, Ontario (Weld 1926, Burks 1979, Ives & Wong 1988, Bergdahl 2015). Within Canada, the authors have observed galls of the sexual generation on introduced bur oaks in Alberta, and on bur oaks within their native range in Manitoba and Quebec.

Bassettia flavipes (Gillette, 1889), comb. nov., asexual generation

[Synonyms listed for the sexual generation]

Material examined: Fifteen females “Canada, Alberta, University of Alberta, Edmonton, leg. S. Digweed, 27/04/2007, Q. macrocarpa”

Gall. Asexual galls (Fig. 93) are inconspicuous stem galls comprised of individual larval cells within corky bark on 2–3 year old twigs of Q. macrocarpa. Galls are not evident as swellings on twig surfaces. Galls are not induced on twigs of the previous year’s growth, nor are they present in smooth twigs. 

Biology. Asexual females of B. flavipes emerged in mid- to late April in Edmonton and oviposited into swelling buds, preferring those having the bud scales slightly open with green showing between them. Females actively palpated prospective buds, and briefly probed them by inserting their ovipositors between bud scales. Females then quickly plunged their ovipositors fully into the bud, oviposited for 10-20 seconds, retracted their ovipositors, and departed. Females mostly seemed to avoid buds into which they or other females had previously oviposited. 

Sexual generation galls have been recorded from Q. macrocarpa and Q. alba (Burks 1979, Weld 1926), and the authors additionally observed them on Q. ⨯ bebbiana (Q. alba x Q. macrocarpa) and Q. ⨯ schuettei (Q. bicolor x Q. macrocarpa) at the Jardin Botanique de Montreal in August 2007.

Distribution. USA: Illinois, Indiana, Iowa, Minnesota, North Dakota, Virginia; Canada: Alberta, Ontario (Weld 1926, Burks 1979, Ives & Wong 1988, Bergdahl 2015). Within Canada, the authors have observed galls of the sexual generation on introduced bur oaks in Alberta, and on bur oaks within their native range in Manitoba and Quebec.

Comments. Suspected galls of the asexual generation of B. flavipes have been identified as a source of damage on ornamental bur oaks because, at high population levels, they may attract birds which damage twigs while extracting larvae from galls (Ives & Wong 1988; Bergdahl 2015). Photos of this damage suggest that galls containing larvae may occur on a greater variety of stem sizes and maturities than we observed, perhaps as a function of higher population densities. It is also possible that old galls bearing exit holes, which persist on larger and older stems, house other insects that are sought by birds. 

Rearings of asexual galls of B. flavipes from Edmonton, Alberta produced multiple other gall occupants. The most common (88%) alternative occupant was a species of Ceroptres Hartig, 1840; this genus is an inquiline in cynipid galls, although it is not clear if it is lethal to the original gall inducer (Ronquist et al. 2015). It appeared to specialize on B. flavipes in Edmonton, as it was not reared from other bur-oak-galling cynipids there (S. Digweed, unpublished data). We also reared the chalcid parasitoids Ormyrus labotus Walker, 1843, and Sycophila marylandica (Girault, 1916), from asexual galls. All parasitoids emerged from mid-May to mid-June. We also reared these three species from sexual galls of B. flavipes, as well as adults of the parasitoids Baryscapus racemariae (Ashmead, 1886), Sycophila dubia (Walsh, 1870), and Eurytoma studiosa Say, 1836. These alternative occupants of sexual B. flavipes galls emerged between early July and mid-August. Sycophila foliatae (Ashmead, 1881), S. quercilanae (Fitch, 1859), and S. xanthochroa (Ashmead, 1894), have been reared elsewhere from sexual galls of B. flavipes (Noyes 2016).

Bassettia pallida Ashmead, 1896, sexual generation [See ID Notes!]

Synonyms: Bassettia archboldi Melika & Abrahamson, 2007, syn. nov. This species was initially described based only on males, without knowledge of the females or the galls they induce; a male was obtained in a Malaise trap in November in Florida, at the Archbold Biological Station (Melika & Abrahamson 2007).

Material examined: Two females and one male “Skinners nursery, Crescent City., FL, gall coll. 04/03/24. Tree 20C, Bassettia gall.”. Four males “USA, FL, Highlands Co., Lake Placid, Archbold Bio Sta, 1995.10.11. MT. leg. G. Melika”

Gall. Sexual galls remain to be confirmed but may well be found within hypertrophied buds that occur in clusters on stems, with bud scales open, although with no obvious cavity observed within the bud (Fig. 113). 

Biology. Bassettia pallida, previously known only from asexual females, is now also known from its sexual generation. The asexual galls develop under the bark of twigs on Q. virginiana and Q. geminata. Galls mature in late September-October; adults emerge in November. Both sexual females and males were reared from galls within the same twig with enlarged and distorted buds on it, collected at the Archbold Biological Station (Florida) from Q. geminata in October. See Weinersmith et al. (2020) for the community ecology and natural enemy assemblage associated with galls. 

Distribution. USA: Florida, Georgia, Missouri (Burks 1979).

Bassettia pallida Ashmead, 1896, sexual generation

Gall. Asexual galls (Fig. 112) are in twigs, larval cells develop as cryptic elliptical chambers 3.2 mm long by 1.2 mm in diameter under the bark of small twigs. 

Biology. Bassettia pallida, previously known only from asexual females, is now also known from its sexual generation. The asexual galls develop under the bark of twigs on Q. virginiana and Q. geminata. Galls mature in late September-October; adults emerge in November. Both sexual females and males were reared from galls within the same twig with enlarged and distorted buds on it, collected at the Archbold Biological Station (Florida) from Q. geminata in October. See Weinersmith et al. (2020) for the community ecology and natural enemy assemblage associated with galls. 

Distribution. USA: Florida, Georgia, Missouri (Burks 1979).

Melikaiella tumifica (Osten Sacken, 1865), asexual generation

Material examined: 15 asexual females labelled as “Germany, Baden-Württemberg, Schwetzinger Hardt, 10km SW of Heidelberg, ex acorns on Q. rubra, coll. R. Beiderbeck, 2014.10.01, emerge 2017.03.22”. 

Gall. Asexual galls (Fig. 120) are in acorns (Beiderbeck & Nicholls 2014). The acorns are stunted, smaller than a non-infected acorn, and contain up to 6–7 cryptic larval chambers; the cotyledons are brown or used up by the larvae (Beiderbeck & Nicholls 2014). 

Biology. See Beiderbeck (2012), Beiderbeck & Nicholls (2014), and Pujade-Villar et al. (2014) for the biology of this species. The sexual generation develops on Q. rubra and Q. velutina; the asexual only known so far from Q. rubra. Sexual generation leaf galls develop in early spring; adults emerge in May-June. Asexual acorn galls were found in October - November, maturing in November. Adults overwinter in galls and emerge in the following spring. 

Distribution. USA: New York, Virginia, North Carolina, Illinois, Iowa (Burks 1979). Also an introduced species in Germany (Heidelberg) on introduced Q. rubra (Beiderbeck 2012, Beiderbeck & Nicholls 2014).

Melikaiella tumifica (Osten Sacken, 1865), asexual generation

Material examined: 15 asexual females labelled as “Germany, Baden-Württemberg, Schwetzinger Hardt, 10km SW of Heidelberg, ex acorns on Q. rubra, coll. R. Beiderbeck, 2014.10.01, emerge 2017.03.22”. 

Gall. Sexual generation gall (Fig. 119) is a large, multilocular thickening of the leaf midrib/petiole. 

Biology. See Beiderbeck (2012), Beiderbeck & Nicholls (2014), and Pujade-Villar et al. (2014) for the biology of this species. The sexual generation develops on Q. rubra and Q. velutina; the asexual only known so far from Q. rubra. Sexual generation leaf galls develop in early spring; adults emerge in May-June. Asexual acorn galls were found in October - November, maturing in November. Adults overwinter in galls and emerge in the following spring. 

Distribution. USA: New York, Virginia, North Carolina, Illinois, Iowa (Burks 1979). Also an introduced species in Germany (Heidelberg) on introduced Q. rubra (Beiderbeck 2012, Beiderbeck & Nicholls 2014).

Neuroterus floccosus (Bassett, 1881), comb rev., sexual generation

[Synonyms listed for agamic gall]

Material examined: Nine asexual females labelled as “Canada, Manitoba, Assiniboine Forest, 49.85862°N, - 97.25015°W, GPS ±10m, S. Digweed, Collected 2005.viii.30 ex Quercus macrocarpa, Reared 15-25.v.2006 ex gall of Neuroterus quercusverrucarum agamic gen.”, determined originally as Neuroterus quercusverrucarum asexual generation females by S. Digweed. Seven sexual females and 4 males labelled as “Canada, Alberta, Edmonton, Northern Forest Centre, 53.49165°N, -113.54291°W, GPS ±10m, Reared 4-13.vii.2006 ex galls of Neuroterus quercusverrucarum ♂♀ ex Quercus macrocarpa, S. Digweed”

Gall. Sexual generation minute (approximately 1mm long), ovoid, seed-like integral leaf galls, smooth and only covered with normal leaf pubescence (Fig. 150). Galls are visible and project slightly from both upper and lower leaf surfaces, and often but not always occur alongside major leaf veins. Galls appear reddish-brown from above and paler tan from below. Exit holes of adult insects generally occur on the underside of the leaf. 

Biology. Asexual galls (Fig. 149) have been recorded on leaves of Q. bicolor and Q. macrocarpa. Galls become apparent in August as small depressions filled with loose, pale wool on the underside of new, terminal, long shoot leaves. Multiple galls often co-occur on a single leaf, which causes the leaf to curl, and galls tend to be found on stumps or damaged trees bearing vigorous, long late-season shoots. Adult females of the asexual generation emerge the spring following gall induction, from mid-April to late May. Galls of the sexual generation first appeared in late May on Q. macrocarpa in Edmonton, and adults emerged in late July and early August. 

Distribution. USA: from Virginia west to Illinois (Burks 1979). Canada: Ontario (Burks 1979), Manitoba. This species was only reared in sleeves in Edmonton, Alberta, and does not naturally occur on bur oak there. 

Neuroterus floccosus (Bassett, 1881), comb rev., sexual generation

Synonyms: Cynips floccosa Bassett (1881b: 111), asexual female, gall. Neuroterus floccosus combination by Mayr (1881: 37). Neuroterus verrucarum var. floccosus combination by Kinsey (1923: 70); combination of Mayr (1881) restored by Weld (1951: 621). 
Neuroterus verrucarum var. pernotus Kinsey, 1923. Synonymized by Weld (1951: 621). 
Melika & Abrahamson (1997) erroneously synonymized N. floccosus with N. quercusverrucarum. 

Biology. See Bassett (1881b), Beutenmueller (1910), and Weld (1926) for the biology of the asexual generation. Asexual galls (Fig. 149) have been recorded on leaves of Q. bicolor and Q. macrocarpa. Galls become apparent in August as small depressions filled with loose, pale wool on the underside of new, terminal, long shoot leaves. Multiple galls often co-occur on a single leaf, which causes the leaf to curl, and galls tend to be found on stumps or damaged trees bearing vigorous, long late-season shoots. Adult females of the asexual generation emerge the spring following gall induction, from mid-April to late May. Galls of the sexual generation first appeared in late May on Q. macrocarpa in Edmonton, and adults emerged in late July and early August. 

Distribution. USA: from Virginia west to Illinois (Burks 1979). Canada: Ontario (Burks 1979), Manitoba. This species was only reared in sleeves in Edmonton, Alberta, and does not naturally occur on bur oak there. 

Neuroterus niger Gillette, 1888 

Synonyms: Neuroterus nigrum Gillette (1888: 218), females and galls. Revised spelling by Dalla Torre and Kieffer (1902: 51). 
Neuroterus papillosus Beutenmueller, 1910, syn. nov. 
Neuroterus perminimus Bassett, 1900. Synonymized by Beutenmueller (1910: 121), and treated as a variety of N. niger by Kinsey (1923: 48), but synonymy ignored by Weld (1951) and later authors; syn. nov. 
Kinsey (1923) described 5 additional varieties of N. niger, all inducing integral leaf galls. Four we consider as synonyms: Neuroterus niger var. arizonicae Kinsey, 1923 (asexual generation, Arizona, on Q. arizonica), syn. nov.; Neuroterus niger var. grisea Kinsey, 1923 (asexual generation, Texas, on Q. grisea), syn. nov.; Neuroterus niger var. nigripes Kinsey, 1923 (asexual generation, Texas, on Q. sinuata var. breviloba (=Q. breviloba) and Q. stellata), syn. nov.; Neuroterus niger var. pattersoni Kinsey, 1923 (asexual and sexual generations, Texas, on Q. sinuata var. breviloba (=Q. breviloba) and Q. stellata, respectively), syn. nov.. 

The fifth variety described by Kinsey is Neuroterus niger var. alimas Kinsey, 1923 (sexual generation, Texas, on Q. virginiana) that was still considered as form of N. niger by Burks (1979). According to Kinsey (1923) this variety induces a sexual generation spring gall, while the other four varieties induce autumn asexual generation galls. Moreover, N. niger var. alimas is the only variety associated with section Virentes oaks while the other four are on section Quercus oaks, and as mentioned in the Introduction, no Nearctic cynipid species are shared across the oak sections (Abrahamson et al. 1998a, 2003; Stone et al. 2009). Hence biological information suggests that N. niger var. alimas is a species distinct from N. niger (sensu Gillette 1888) and the other four of Kinsey’s varieties. Kinsey (1923) described N. niger var. alimas based on one female (holotype – lost) and 13 males and gave no detailed morphological description for this variety. Thus, there is no morphological evidence for synonymisation of N. niger var. alimas to N. niger while at the same time it cannot be treated as a valid species so Melika et al. (2021) moved it to nomen dubium.

Gall. The asexual generation gall is described by Gillette (1888) and are small blisters integral to the leaf blade (Fig. 181). 

Biology. See Gillette (1890), Beutenmueller (1910), Kinsey (1923), and Weld (1926) for the biology of one or both generations. The minute, integral leaf galls of the asexual generation have been recorded on Q. macrocarpa. Galls became evident in Edmonton in August and matured in September. This species represents a rare case where males are present in the asexual generation. Males of the asexual generation comprised a tiny fraction of the cynipids reared from asexual generation galls, with only 62 males reared from gall collections made in Edmonton during 2004- 2006, as opposed to 20979 females. In addition, most males were reared in the autumn (October-December) of the year of gall formation, whereas almost all females emerged in April-May the following spring after gall formation. Thus, most males were temporally isolated from ovipositing females and therefore essentially functionless. This is similar to Patterson’s (1928) discovery of functionless males of the asexual generations of Neuroterus contortus (Weld, 1921) and N. quercusrileyi (Bassett, 1881). In his study, males and females co-occurred, but they appeared unwilling to mate under laboratory conditions. Galls of the sexual generation are on Q. alba, Q. bicolor and Q. macrocarpa (Gillette 1890, Burks 1979, Digweed 2010). We observed that clusters of galls (e.g., on one catkin) often produced adults of only one gender. Galls were visible in Edmonton in May, with adults emerging in late May or early June. Sexual generation females were observed ovipositing mostly on the undersides of leaves and often on leaves that were on long shoots and/or that were not yet fully mature. 

Distribution. In the USA the asexual generation has been recorded from Massachusetts, Michigan, Wisconsin, Iowa (Burks 1979), Illinois, Indiana, New York, New Jersey, Pennsylvania, Ohio (Beutenmueller 1910); Arizona, Texas (Kinsey 1923), and Alberta and Manitoba in Canada. The sexual generation has been recorded from Illinois (Weld 1926), Iowa (Burks 1979), and TX (Kinsey 1923) in the USA and Alberta in Canada.

Neuroterus niger Gillette, 1888

Neuroterus vernus Gillette, 1889, sexual generation, syn. nov. 

Material examined. Five asexual females labelled as “CANADA: Alberta, Edmonton, Grand Trunk Pool, SC30, 2002.04.12. S. Digweed, Neuroterus niger Gillette females of the asexual generation, det. S. Digweed 2005”. Sexual generation: 5 females labelled as “CANADA, Alberta, Edmonton. Reared 18.iv.2005, ex Q. macrocarpa. N. niger (?) gall, Grand Trunk, coll.22.ix.04. S. Digweed”; 5 males labelled as “CANADA, Alberta, Edmonton. Reared 3-13.x.2005, ex Q. macrocarpa. N. niger (?) gall, Grand Trunk, coll.22.ix.04. S. Digweed”.

Gall. The sexual generation galls (Fig. 182), first recorded as N. vernus, are cells hidden within new shoots, on the young leaf petioles and midribs and on the catkins of Q. macrocarpa; these plant organs are sometimes distorted as a result (Digweed 2010). 

Biology. Galls of the sexual generation are on Q. alba, Q. bicolor and Q. macrocarpa (Gillette 1890, Burks 1979, Digweed 2010). We observed that clusters of galls (e.g., on one catkin) often produced adults of only one gender. Galls were visible in Edmonton in May, with adults emerging in late May or early June. Sexual generation females were observed ovipositing mostly on the undersides of leaves and often on leaves that were on long shoots and/or that were not yet fully mature. 

Distribution. In the USA the asexual generation has been recorded from Massachusetts, Michigan, Wisconsin, Iowa (Burks 1979), Illinois, Indiana, New York, New Jersey, Pennsylvania, Ohio (Beutenmueller 1910); Arizona, Texas (Kinsey 1923), and Alberta and Manitoba in Canada. The sexual generation has been recorded from Illinois (Weld 1926), Iowa (Burks 1979), and TX (Kinsey 1923) in the USA and Alberta in Canada.

Philonix fulvicollis Fitch, 1859(1858), sexual generation

Comments. Kinsey (1930) transferred Dryophanta pallipes Bassett, 1900 to Philonix and proposed it as the sexual generation of P. fulvicollis, although no justification for this synonymy was provided. Weld (1959) wrote that P. pallipes might be well a synonym of Acraspis gemula. Melika & Abrahamson (2002) compared the three specimens of P. pallipes (from Beutenmueller collection, USNM, Washington, DC) with the paratypes of the sexual generation of A. gemula and found no differences, thus Philonix pallipes was synonymized with A. gemula. 

Philonix fulvicollis Fitch, 1859(1858), sexual generation

Material examined: One sexual female and one male labelled as “CANADA: Alberta, Edmonton, 3761-20 Street, 53.47371°N, 113.37202°W, GPS±10m, reared 1.vi.2008 ex bud galls on Quercus macrocarpa, S. Digweed, det. Philonix fulvicollis Fitch, sexual generation female, S. Digweed 2008”

Gall. The sexual generation galls (Fig. 204) occur singly in terminal buds of twigs of Q. macrocarpa. The gall is a relatively robust, seed-like, sub-ovoid cell approximately 2 mm long, dark brown when mature with longitudinal striations. Occupies the entire bud when mature, causing stunting or suppression of shoots and leaves produced from the bud. 

Biology. Asexual generation galls (Fig. 203) in Kinsey’s (1936) “fulvicollis” complex have been recorded on leaves of Q. alba, Q. bicolor, Q. chapmanii, Q. gambelii, Q. lyrata, Q. macrocarpa, Q. michauxii, Q. muehlenbergii, and Q. stellata, (Kinsey 1930, 1936; Burks 1979). Asexual generation females only begin to emerge from galls in the autumn of the year following the year of gall formation (Kinsey 1930), and we recorded females emerging up to four years after the year of gall formation. Adult females of the asexual generation (from galls collected in Manitoba but reared in Edmonton) emerged during the second half of October and early November. Sexual generation galls matured in May in Edmonton, and adults emerged 1–3 June 2008. Galls of the asexual generation appeared on leaves in Edmonton in July. 

Distribution. USA: New York, Michigan, Tennessee, Illinois, Kansas (Burks 1979); Canada: Manitoba, Ontario, Quebec, New Brunswick.

Comments. Kinsey (1930) transferred Dryophanta pallipes Bassett, 1900 to Philonix and proposed it as the sexual generation of P. fulvicollis, although no justification for this synonymy was provided. Weld (1959) wrote that P. pallipes might be well a synonym of Acraspis gemula. Melika & Abrahamson (2002) compared the three specimens of P. pallipes (from Beutenmueller collection, USNM, Washington, DC) with the paratypes of the sexual generation of A. gemula and found no differences, thus Philonix pallipes was synonymized with A. gemula. 

Philonix fulvicollis Fitch, 1859(1858), sexual generation

Synonyms: Philonix fulvicollis Fitch (1859: 783), asexual females; Cynips (Teras) fulvicollis combination by Osten Sacken (1865: 379); Biorhiza fulvicollis combination by Ashmead (1885: 296); Biorrhiza fulvicollis combination and incorrect spelling by Dalla Torre (1893: 61); Philonyx fulvicollis combination and incorrect spelling by Smith (1910: 598); Cynips (Philonix) fulvicollis var. fulvicollis form fulvicollis combination by Kinsey (1930: 262); Cynips (Philonix) fulvicollis combination by Kinsey (1936: 207). 
Philonix nigricollis Fitch, 1859. Synonymized by Kinsey (1930: 262). 
Acraspis niger Gillette, 1889. Acraspis nigra corrected spelling by Dalla Torre (1893: 64); Philonix nigra combination by Beutenmueller (1909: 251); Philonyx nigra combination and incorrect spelling by Smith (1910: 598); Philonix niger correction by Felt (1918: 96). Synonymized by Kinsey (1930: 262). 
Acraspis gillettei Bassett, 1900. Acraspis gillettii incorrect spelling by Beutenmueller (1904: 25); Philonix gillettei combination by Felt (1906: 711); Philonyx gillettei combination and incorrect spelling by Smith (1910: 598). Synonymized by Beutenmueller (1909: 252). 
Kinsey (1930, 1936) described 6 additional species from the asexual generation and included them within his “fulvicollis complex”: Cynips (Philonix) canadensis Kinsey, 1930 on Q. alba, Q. macrocarpa, Q. michauxii, and Q. muehlenbergii; Cynips (Philonix) major Kinsey, 1930 on Q. alba, Q. macrocarpa, Q. michauxii, and Q. muehlenbergii; Cynips (Philonix) rubricosa Kinsey, 1930 on Q. alba and Q. stellata, Cynips (Philonix) vorisi Kinsey, 1930 on Q. bicolor, Q. michauxii, and Q. macrocarpa; Cynips (Philonix) insulensis Kinsey, 1936 on Q. gambelii and Q. macrocarpa; and Cynips (Philonix) latigenae Kinsey, 1936 on Q. gambelii. Kinsey also included in this complex the taxa Philonix gigas Weld, 1922 on Q. lyrata and Philonix lanaeglobuli (Ashmead, 1887) on Q. michauxii, both known only from an asexual generation, plus Philonix pallipes (Bassett, 1900), known only from a sexual generation on Q. alba. Since then, Melika & Abrahamson (2002) synonymized Philonix pallipes to Acraspis gemula (Bassett, 1881). Weld (1951) and Burks (1979) treated Philonix insulensis (Kinsey), Philonix latigenae (Kinsey), Philonix gigas Weld, and Philonix lanaeglobuli (Ashmead) as distinct valid species, while the rest were treated as varieties of P. fulvicollis. We follow this treatment, thus Philonix fulvicollis var. canadensis (Kinsey), syn. nov., Philonix fulvicollis var. major (Kinsey), syn.nov., Philonix fulvicollis var. rubricosa (Kinsey), syn. nov. and Philonix fulvicollis var. vorisi (Kinsey), syn. nov. are all considered synonyms of P. fulvicollis

Gall. The sexual generation galls (Fig. 204) occur singly in terminal buds of twigs of Q. macrocarpa. The gall is a relatively robust, seed-like, sub-ovoid cell approximately 2 mm long, dark brown when mature with longitudinal striations. Occupies the entire bud when mature, causing stunting or suppression of shoots and leaves produced from the bud. 

Biology. See Fitch (1859), Weld (1922a, 1926), and Kinsey (1930, 1936) for the biology of the asexual generation. Asexual generation galls (Fig. 203) in Kinsey’s (1936) “fulvicollis” complex have been recorded on leaves of Q. alba, Q. bicolor, Q. chapmanii, Q. gambelii, Q. lyrata, Q. macrocarpa, Q. michauxii, Q. muehlenbergii, and Q. stellata, (Kinsey 1930, 1936; Burks 1979). Asexual generation females only begin to emerge from galls in the autumn of the year following the year of gall formation (Kinsey 1930), and we recorded females emerging up to four years after the year of gall formation. Adult females of the asexual generation (from galls collected in Manitoba but reared in Edmonton) emerged during the second half of October and early November. Sexual generation galls matured in May in Edmonton, and adults emerged 1–3 June 2008. Galls of the asexual generation appeared on leaves in Edmonton in July. 

Distribution. USA: New York, Michigan, Tennessee, Illinois, Kansas (Burks 1979); Canada: Manitoba, Ontario, Quebec, New Brunswick.

Comments. Digweed (2010) treated Philonix gigas (Weld), Philonix insulensis (Kinsey), and Philonix nigra (Gillette) as synonyms of P. fulvicollis, although without formal synonymization. Molecular analysis, however, shows that P. fulvicollis and P. nigra are distinct species. 

Phylloteras poculum (Osten Sacken, 1862), sexual generation

Synonyms: Cecidomyia poculum Osten Sacken (1862: 201), galls. Xystoteras poculum combination and description of adult females by Weld (1922a: 7); Phylloteras poculum combination by Lyon (1993: 133). 

Gall. Galls of the asexual generation (Fig. 224) on Q. alba are as described by Osten Sacken (1862) and Weld (1922a). 

Biology. See Weld (1922a) for the biology of the asexual generation. Galls of the asexual generation became evident on bur oak leaves in Edmonton in July, and were fully mature in September, when many separate easily from the leaf lamina, falling to the ground. Galls are susceptible to drying, and rearing experience suggests that desiccated galls produce no emergents. Females of the asexual generation overwinter and pass the entire subsequent summer in their galls, emerging in late autumn and winter – generally from late October to December with a peak in mid-November, but when a large number of galls was reared over winter 2016-2017 in Edmonton, a small number of females emerged in all months from January through April 2017. Weld (1922a) reared adults in Evanston, Illinois, in March. The brachypterous females were observed in Edmonton to crawl up through any accumulated snowpack, climb bur oak stems, and oviposit in buds. Emergence and adult female activity appeared delayed in autumn during periods of warmer weather, and was observed during a period of sustained temperatures ranging from -10°C to -17°C during early January 2017 in Edmonton. Galls of the sexual generation became apparent in early May in Edmonton, with adults emerging from mid-May through mid-June. This species has not been previously recorded from Q. macrocarpa; earlier records are from Q. alba and Q. montana. Another congeneric species, Phylloteras volutellae (Ashmead, 1897), is also found on Q. macrocarpa. 

Distribution. USA: Virginia, New York, Vermont, New Hampshire, Illinois, Missouri (Burks 1979). Canada: Manitoba, Alberta.

Phylloteras poculum (Osten Sacken, 1862), sexual generation

Material examined: Five males and five females of the sexual generation, labelled as “CANADA: Alberta, Edmonton, Brennan Crescent, 53.51746°N, -113.682957°W, Google Maps, bud/shoot/ament galls collected 21.v.2018 ex Quercus macrocarpa, S. Digweed, reared 24-30.v.2018”

Gall. Sexual galls (Fig. 225) are exposed, thin-walled, seed-like, ovoid, brown chambers in buds, catkins, and proximal regions of immature leaf midribs and laminae. Sometimes with a sparse pubescence of fibrous, tan hairs; sometimes these hairs are more abundant as a distal tuft. Adults emerge through holes chewed in the distal half of galls. Aging galls can persist on buds and leaves into autumn. 

Biology. Galls of the sexual generation became apparent in early May in Edmonton, with adults emerging from mid-May through mid-June. This species has not been previously recorded from Q. macrocarpa; earlier records are from Q. alba and Q. montana. Another congeneric species, Phylloteras volutellae (Ashmead, 1897), is also found on Q. macrocarpa. 

Distribution. USA: Virginia, New York, Vermont, New Hampshire, Illinois, Missouri (Burks 1979). Canada: Manitoba, Alberta.

Sphaeroteras carolina (Ashmead, 1887), comb. rev., sexual generation 

[Synonyms listed for agamic generation]

Material examined: 2 females as “USA, Florida, Manatee Co., Lake Manatee SRA, leg. J. Nicholls, 2008.04.16. FL1097, spFLb4; ex Quercus chapmanii”.

Gall. Sexual galls (Fig. 237) on small twigs. Initially red/yellow, becoming darker as they mature, with pale pubescence, pear-shaped, tip bent to one side, 6–7 mm long, 3 mm diameter at widest point. 

Biology. Asexual detachable rounded galls (Fig. 236) on leaves on Q. alba, Q. chapmanii and Q. stellata (Burks 1979). Sexual galls mature in April; adults emerge soon afterwards; to date found only on Q. chapmanii. 

Distribution. USA: North Carolina, Florida, Missouri, Arkansas, Texas (Burks 1979).

Sphaeroteras carolina (Ashmead, 1887), comb. rev., sexual generation 

Synonyms: Dryophanta carolina Ashmead (1887: 145), asexual females, galls. Sphaeroteras carolina (Burks 1979). Atrusca carolina (Melika & Abrahamson 2002).

Biology. Asexual detachable rounded galls (Fig. 236) on leaves on Q. alba, Q. chapmanii and Q. stellata (Burks 1979). Sexual galls mature in April; adults emerge soon afterwards; to date found only on Q. chapmanii. 

Distribution. USA: North Carolina, Florida, Missouri, Arkansas, Texas (Burks 1979).

Pairing of sexual and asexual generations of Nearctic oak gallwasps, with new synonyms and new species names (Hymenoptera: Cynipidae, Cynipini)