Neuroterus Hartig, 1840

Melika, George, Nicholls, James A., Abrahamson, Warren G., Buss, Eileen A. & Stone, Graham N., 2021, New species of Nearctic oak gall wasps (Hymenoptera: Cynipidae, Cynipini), Zootaxa 5084 (1), pp. 1-131 : 90

Neuroterus Hartig, 1840

Neuroterus has historically been a complex genus. As originally defined, species of this genus (including the Neuroterus species described here) have a mesonotum that is thinner and more weakly sclerotized than is typical for other cynipid genera and the transscutal articulation is absent, either partially (in its median section) or entirely. As a result of the fusion of the mesoscutum (which is slightly invaginated medially) and mesoscutellum, the boundary between these structures is not straight but slightly curved towards the mesoscutum; in addition, the mesoscutum is emarginate posterolaterally and slightly elevated above the dorsoaxillar area. In all other Nearctic Cynipini genera the transscutal articulation is straight, as is the boundary between the mesoscutum posteriorly and mesoscutellum anteriorly; however, in some apterous Nearctic genera ( Acraspis , Biorhiza Westwood, 1840 , Phylloteras Ashmead, 1897 , Zopheroteras Ashmead, 1897 ) this articulation is present although very reduced ( Melika & Abrahamson 2002).

Elevated heterogeneity within this genus was demonstrated by Kinsey (1923) when he subdivided Neuroterus into six subgenera on the basis of adult morphology, geographic distribution, gall structure, and life cycles, underlining the fact that this group is biologically diverse and unlikely to be monophyletic. Additional Asian taxa were placed in this genus thus further increasing the heterogeneity ( Monzen 1954; Abe 2006), although the divergent subgenus Pseudoneuroterus Kinsey, 1923 was raised to full genus status by Pujade-Villar et al. 2004. Subsequent phylogenetic reconstructions strongly challenged the monophyly of Neuroterus ( Stone et al. 2009, Liljeblad et al. 2008), prompting significant revision of some distinct lineages within the Palaearctic component of Neuroterus through creation or re-establishment of the genera Cerroneuroterus Melika & Pujade-Villar 2010 , Trichagalma Mayr, 1907 and Latuspina Monzen, 1954 ( Melika et al. 2010). However, molecular data show that even the most recent definition of Neuroterus is still not monophyletic ( Stone et al. 2009; Nicholls et al. 2017; Nicholls et al. 2018b; Nieves-Aldrey et al. 2021).

Currently just over 50 species of Neuroterus are known from America north of Mexico and a further 15 species from Mexico and central America ( Kinsey 1938; Burks 1979; Lyon 1984; Melika & Abrahamson 1997a; Pujade-Villar et al. 2015a, 2016, 2017c, 2018b; Pujade-Villar & Hanson 2021; Medianero & Nieves-Aldrey 2017). Nearly all of these species induce galls on Quercus section Quercus with the exception of one species with its host plant in section Protobalanus , four species that gall hosts in section Virentes and a single species galling the section Ponticae; the latter two oak sections were recently split out from a broader definition of section Quercus by Denk et al. (2017). Herein we describe seven new species of Neuroterus , six of which are associated with Quercus section Quercus and one with section Virentes .