Macrostigmoraphia, 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

Genus Macrostigmoraphia gen. nov.

urn:lsid:zoobank.org:act:67388462-CDFA-46FA-8803-B2978E50605C

Type and only species. Macrostigmoraphia diluta sp. nov.

Etymology. From the Greek macros, long, stigma, spot, and Raphidia , a genus-group name of Raphidiidae . Gender feminine.

Diagnosis. May be distinguished from other genera by configuration of pterostigma: it is very long (10 times as long as wide), very pale, and lacks any incorporated veinlets or crossveins.

Remarks. The specimen has been placed within Raphidiidae based on the combination of 2sc-r being far distad the termination of Sc [ Inocelliidae : located near termination of Sc], closing the proximal end of pterostigma [ Inocelliidae : sc-r not closing pterostigma proximally].

The long pterostigma closed proximally by crossvein 2sc-r and often without incorporated veinlets is also present in the genera of the Cretaceous tribe Nanoraphidiini ( Mesoraphidiidae ). In general, their venation is very similar to that of some Raphidiidae , particularly the late Eocene subfamily Succinoraphidiinae Aspöck & Aspöck, 2004 ( Perkovsky & Makarkin 2019). Apart from the long pterostigma, the rest of the forewing venation of Macrostigmoraphia gen. nov. is typical of the Eocene Raphidiidae . The venation of all species of Nanoraphidiini (except one wing of Rhynchoraphidia burmana Liu et al., 2016 : Fig. 6B ) differs from it, in particular by the simple (not forked) anterior trace of RP distad of 3ra-rp [two branches are present in Macrostigmoraphia gen. nov.]. It cannot be ruled out, however, that the new genus may theoretically belong to Nanoraphidiini or another group of Mesoraphidiidae , but currently there is insufficient data for this conclusion.

The few crossveins and a lack of an enriched venation separate the specimen from Baissopteridae .

The slight bend of RA proximad 3ra-rp might be indicative of the last distal veinlet, closing the pterostigma distally (indiscernible by preservation). In this case, 3ra-rp would be located distad the pterostigma, but it is very unlikely as this crossvein is located within the pterostigma in all known Eocene Raphidiidae (see Archibald & Makarkin 2021). In Nanoraphidiini , both conditions are present: 3ra-rp may be located proximad or distad the pterostigma (see Makarkin 2023). If the indiscernible veinlet exists, then RA has two distal veinlets, but all known Nanoraphidiini only have one. Therefore, if this is either Raphidiidae or Nanoraphidiini , the very long pterostigma is characteristic of the genus, not an artefact.

Figures

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).