Cenocimbicinae, Archibald & Rasnitsyn, 2023

Archibald, S. Bruce & Rasnitsyn, Alexandr P., 2023, Cimbicidae (Hymenoptera, ‘ Symphyta’) in the Paleogene: revision, the new subfamily Cenocimbicinae, and new taxa from the Eocene Okanagan Highlands, Zootaxa 5278 (1), pp. 1-38 : 4

Subfamily Cenocimbicinae n. subfam.

http://zoobank.org/ urn:lsid:zoobank.org:act:FA885793-D7D8-49A8-A00D-6C813ACBFC0F

Type genus. Cenocimbex Nel, 2004 .

Diagnosis. Distinguished from all other Cimbicidae by forewing with 2r-m distinctly curved, meeting M distal of 2m-cu; cell 2r+pterostigma distinctly higher than cell 3r; and a combination of the following: eyes converging ventrally; antenna with 7–9 antennomeres, club 3-segmented; mesonotum with median longitudinal mesonotal sulcus and notauli distinct; metanotum short, with cenchri oval; tibial spur acute, long; first abdominal tergite with hind margin straight or weakly emarginated.

Remarks. Cenocimbicinae differ from individual subfamilies of Cimbicidae by: from all by 2r-m as in diagnosis; from Abiinae , Cimbicinae by eyes converging ventrally [ Cimbicinae : more or less parallel; Abiinae : converging dorsally], by at least one tibial spur acute, long (equal length of first tarsomere, one known, see F-774, tentative Leptostigma brevilatum ) [ Abiinae , Cimbicinae: blunt]; from Corynidinae, Pachylostictinae by 2r-m posterior insertion distal to cell 2mcu [Corynidinae, Pachylostictinae : proximal to], by cell 2r+pterostigma distinctly higher than cell 3r [not so], antenna with more than five antennomeres [five], club 3-segmented [non-segmented], metanotum short [long]; further from Corynidinae by mesonotum with median longitudinal mesonotal sulcus and notauli distinct [reduced or absent]; from some Abiinae and Cimbicinae by cenchri oval, from some Cimbicinae also by first abdominal tergite with hind margin straight or weakly emarginated [deeply emarginated].

Attribution of the Cenocimbicinae to the Tenthredinoidea is confident by 1-M meeting R and 2r-rs meeting Rs distally to 2r-m, and to the Cimbicidae by their clubbed antenna, and a unique forewing venation characteristic of the core cimbicid subfamilies Cimbicinae and Abiinae and found nowhere else in Hymenoptera : venation complete for Hymenoptera (except Sc, Rs between Rs+M and 1r-rs, and Rs bifurcation lost), characteristically narrow (low) cell 3r, and 2r-m crossvein meets M distal to 2m-cu.

The long, curved to strongly curved crossvein 2r-m is distinct, occurring only rarely in extant Cimbicidae (very few Abiinae , cf. Vilhelmsen 2019, Fig. 16A ; and Cimbicinae , cf. Vilhelmsen 2019, Fig. 16B ) and in the Miocene of China ( Abiinae : cf. Zhang et al. 1994, Fig. 121; Cimbicinae : cf. Zhang et al. 1994, Fig. 118), which we consider convergent.

The new subfamily comprises the oldest known Cimbicidae , from the Selandian of Menat and less than ten million years later in the Ypresian Okanagan Highlands deposits of far-western North America (Archibald et al. 2011), a rather narrow interval of time but across a great distance of the Holarctic.

Genera included. The type genus, Allenbycimbex n. gen. and Leptostigma n. gen.

Locality and age. Menat, France, Selandian; Okanagan Highlands (McAbee,Allenby Formation, and Republic), far-western North America, Ypresian.

Figures

FIGURE 16. Leptostigma longitenebricum holotype F-1565, A, photograph, B–C, wing drawings: B, left forewing; C, right forewing. All to scale, 5 mm.