Hemerobiidae Leach 1815

Hemerobiidae gen. et sp. A

Figs 3, 4

Material examined. PIN 3364/3751 (part and counterpart); a poorly preserved incomplete forewing.

Locality and horizon. Uglovoi Stream, a right tributary of the Zerkal’naya [=Tadushi] River, eastern Sikhote-Alin Mts, Primorskii Krai, Russian Far East. Tadushi Formation; early/middle Eocene.

Description. Forewing ca. 10 mm as preserved (estimated complete length ca. 14–15 mm), ca. 6.6 mm wide as preserved (estimated complete width ca. 7 mm). Costal space fragmentarily preserved; its costal margin poorly discernible, approximately twice broader than subcostal space in distal part; basal subcostal veinlets probably once forked; distal subcostal veinlets probably simple. Subcostal space very broad through entire length. RA space moderately broad. RP basally poorly discernible, some branches distally rather deeply forked; RP1 at least once deeply forked (alternatively: ORB1 (RP1) deeply forked, with two to three preserved anteriorly directed branches). M forked at level of RP1, probably profusely branched (most part of that space not preserved); branches slightly sigmoidal distally. CuA with six long branches; CuA1 located very proximally. CuP probably with three long branches. Presumable A1 dichotomously forked distally; anterior trace of presumable A2 similarly forked. No clear crossveins discernible. Maculation: very dark transverse stripe over radial to medial spaces continuous in cubital space by large dark spot; numerous irregular brownish spots over radial to medial spaces distad dark stripe.

Remarks. The counterpart is very poorly preserved and completely uninformative (Fig. 3B). This species is well distinguishable by wing maculation, and it will be undoubtedly assigned to a genus and species when more complete forewing is found.

The very proximal origin of CuA1 as found in this specimen (slightly distad the origin of RP) is an unusual condition in the family. In most hemerobiid taxa, it originates far distad the origin of RP, and very rarely slightly distad it (e.g., in Biramus lunatus Oswald, 1993b).

Also, the presence of the slightly sigmoidal branches of M is a very unusual condition in Hemerobiidae. It is found probably only in two genera, i.e., the mid-Cretaceous Cretoneuronema and the extant Hemerobiella Kimmins, 1940 (see Oswald 1993a: Fig. 60; Liu et al. 2022: Fig. 3).