Archibaldia, Makarkin, 2023

Makarkin, Vladimir N., 2023, Fossil Hemerobiidae (Neuroptera) from the Eocene Tadushi Formation, the Russian Far East, with description of a new genus, Zootaxa 5297 (1), pp. 115-123 : 116

Genus Archibaldia gen. nov.

Type species. Cretomerobius wehri Makarkin et al., 2003 .

Etymology. From the surname of S. Bruce Archibald, in recognition of his gigantic efforts in collecting and study of fossil insects from the Eocene of western North America.

Species included. Archibaldia wehri (early Eocene of western North America), and A. aristovi sp. nov. (early/ middle Eocene of the Russian Far East).

Diagnosis. Relatively large hemerobiids (forewing 10–14 mm long), which may be distinguished from other genera by possession of all of the following forewing character states: (1) crossvein 1r-m present; (2) one to three crossveins between RA and RP1 or RP2; (3) RP1 (=ORB1) with anteriorly directed pectinate branches; (4) M dichotomously branched, i.e., three or more long branches originating proximad third gradate series; (5) CuP forked proximad first gradate series; (6) crossveins between branches of CuP.

Remarks. The new genus is most closely related to the Eocene genus Proneuronema Makarkin et al., 2016 , which includes five species ( Makarkin & Perkovsky 2020): P. wehri , an undescribed species from the Tadushi Formation ( A. aristovi sp. nov.), P. gradatum Makarkin et al., 2016 and P. minor Makarkin et al., 2016 from late Eocene of Baltic amber, and P. sidorchukae Makarkin & Perkovsky, 2020 from late Eocene of Rovno amber. The authors believed that the forewing venation of two former species ( P. wehri and the Tadushi species) are more similar to each other than either is to the European Eocene species, except P. gradatum , which is more or less similar to the former by the presence of character states (3) to (6). These character states occur rather often in some genera of the Megalomus -group (see Makarkin et al., 2016), but their complete set is present only in the new genus, P. gradatum , and the mid-Cretaceous Cretoneuronema jarzembowskii Liu et al., 2022 . By this reason, P. gradatum may also belong to Archibaldia gen. nov., except that it lacks crossvein 1r-m and those between RA and RP1/RP2. However, their absence might be explained by secondary reduction. Futhermore, the maculation of P. gradatum and A. aristovi sp. nov. is similar. Megalomus densistriatus Henriksen, 1922 from the earliest Eocene of Denmark may also belong to Archibaldia gen. nov., but this would require reexamination of the holotype or additional specimens.

The forewing of Cretoneuronema Liu et al., 2022 is also very similar to that of the new genus, but differs from it by the distal fusion of Sc and RA, and by the absence of crossvein 1r-m and those between RA and RP1.

The crossvein between RA and RP1 is present only in A. wehri , A. aristovi sp. nov., and three extant genera, the Australian Carobius Banks, 1909 and Notherobius New, 1988 (Carobiinae) , and the mainly Oriental Zachobiella Banks, 1920 (Zachobiellinae) . It is strange but this crossvein is absent in other genera of the Megalomus -group, which have rich crossvenation.

In Hemerobiidae , the crossvein 1r-m is present only in A. wehri and A. aristovi sp. nov. In the holotype of P. wehri , there are two thin crossveins connecting the basal stem of M and RA before the origin of RP1, either of which might be considered 1r-m (or 1r-m and 1 br-m) ( Fig. 1 ). These are poorly discernible and were overlooked in the original description ( Makarkin et al. 2003). Therefore, this character state may be interpreted as an autapomorphy of Archibaldia gen. nov. Unfortunately, it cannot be reliably identified in impression fossils, and its presence in the oldest hemerobiids is possible.

Figures

FIGURE 1. Archibaldia wehri (Makarkin et al., 2003), comb. nov., holotype UWBM77543 (wetted with ethanol).A, forewing; B, its basal part; C, same, taken under different lighting. a, two basal crossveins between R and M; b, crossveins between RA and RP2. Scale bars = 1 mm (B is not to scale).