Neuroptera, Jepson & Makarkin, 2023

Jepson, James E. & Makarkin, Vladimir N., 2023, Fossil Neuropterida (Insecta: Neuroptera and Raphidioptera) from the middle Eocene Kishenehn Formation, Montana, USA, Zootaxa 5306 (4), pp. 427-444 : 438

Neuroptera fam. gen. et sp. indet.

Fig. 6

Material examined. Specimen USNM PAL 621094, deposited in USNM. A fragmentary wing.

Locality and horizon. Middle Fork of the Flathead River, between Paola and Stanton Creeks approximately 17 miles south of West Glacier; the Coal Creek Member of the Kishenehn Formation, north-western Montana, U.S.A. The Middle Eocene (Luteian).

Description. Wing ca. 5.8 mm long as preserved (estimated complete length approximately 8–10 mm). Costal space relatively narrow. Subcostal veinlets simple, closely spaced. RA space narrow; one crossvein well discernible. Branches of RP closely spaced, dichotomously forked distally. One or two gradate series of crossveins discernible in proximal part of fragment; other crossveins in distal part are possible.

Remarks. The family assignment of this wing fragment is unclear. It may theoretically belong to Hemerobiidae , Berothidae or Dilaridae . The narrow costal space and simple closely-spaced costal veinlets in the distal part of the wing show that this is likely a hind wing. In this case, a dilarid affinity is most probable as the hind wings are heavily maculated only in Dilaridae , especially in the American genus Nallachius Navás, 1909 , and some East Asian species of Dilar Rambur, 1838 (see Adams 1970: Figs 1 , 11, 12; Martins et al. 2018: Fig. 3A ). The arrangement of the preserved crossveins also shows that a dilarid affinity is most probable. However, the mode of terminal branching of the longitudinal veins in Nallachius strongly differs from that of this specimen. The venation of the extant Dilar is more similar to that of the fragment, but still different. Hind wings of Hemerobiidae and Berothidae are hyaline (not maculated), and their crossveins are arranged otherwise.

If this is a forewing, a hemerobiid affinity is most probable, but a berothid affinity is also possible (although very unlikely).

Figures

FIGURE 1. Pseudoameropterus ambiguus gen. et sp. nov., holotype USNM PAL 626076. A, specimen as preserved; B, hind wing venation. Scale bar 10 mm.

FIGURE 3. Palaeochrysa greenwalti sp. nov., holotype USNM PAL 622159. A, specimen as preserved; B, forewing venation; C, hind wing venation. Scale bar 3 mm (all to same scale).

FIGURE 6. Neuroptera fam. gen. et sp. indet., specimen USNM PAL 621094. A, specimen as preserved; B, wing venation. Scale bar 2 mm (both to same scale).