Vetosmylus, Ma & Shih & Ren & Wang, 2020

Ma, Yiming, Shih, Chungkun, Ren, Dong & Wang, Yongjie, 2020, A new genus of lance lacewings from the Middle Jurassic of Inner Mongolia, China, Acta Palaeontologica Polonica 65 (2), pp. 363-369 : 364-365

Genus Vetosmylus nov.

Zoobank LSID: urn:lsid:zoobank.org:act:EA3D9D9B-917C-4877-A484-1CF2FC28749D

Type species: Vetosmylus tentus sp. nov.; see below.

Species included: Vetosmylus tentus sp. nov. and Vetosmylus maculosus sp. nov.

Etymology: From Latin vetus, archaic and osmylus, the common generic suffix of Osmylidae ; referring to the earliest of Osmylinae . Gender is masculine.

Diagnosis. —Wings oval and elongate; forewing with irregular fragmentized spots and the hind wing more hyaline. Forewing: cross-veins in RP radial sector irregularly arranged except for the outer gradate series of cross-veins sometimes partly present); the bifurcation of M beyond origin of RP1; CuA with distinctly multiple dichotomies in distal; A1 relatively long, clearly beyond the half length of CuP; A2 closed to half length of A1, A1 and A2 with numerous oblique pectinate branches; A3 complete and terminating at the margin. Hing wing: CuA with many pectinate branches in distal; CuP obviously shorter than CuA, about two-thirds of it, and the pectinate branches occurring near the middle of CuP; A1 long, exceeded half length of CuP.

Remarks.—Unequivocally this new genus is closely related to Kempyninae and Osmylinae due to the presence of the forked subcostal veinlets in both wings (other osmylid subfamilies commonly have the simple subcostal veinlets), as well as the elongate and pectinately branched hind wing CuP (cf. Spilosmylinae, Protosmylinae, and Gumillinae ) ( Winterton et al. 2019). Kempyninae and Osmylinae overlap significantly in all characteristics of the wings, especially in Kempyninae where there are exceptions in various genera which do not display the diagnostic feature for the subfamily. A feature often cited as being diagnostic for Kempyninae is the presence of an expanded area between MA and MP, which is often subdivided into multiple rows of irregular cells with sinuous crossveins ( Wang et al. 2011; Khramov 2014; Winterton et al. 2017, 2019; Khramov et al. 2019). Osmylinae typically have the expanded area between MA and MP, but it contains only a single row of cells and the crossveins are not sinuous. Kempynines typically also have the distal branches of RP being rather sinuous while they are only broadly curved in Osmylinae . The exceptions to this rule in Kempyninae are Australysmus Kimmins, 1940 , Euosmylus Krüger, 1913 , which display the typical Osmylinae states for each character. Unfortunately, to conclusively discriminate between Osmylinae and Kempyninae examination of the male and/or female genitalia is required, and most fossils comprise only wing venation characters. There are several examples of fossil genera being transfered between Kempyninae and Osmylinae based on differing subjective interpretations of the wings, especially where the venation is incomplete. While the female terminalia of Vetosmylus maculosus sp. nov. is preserved in this fossil, the important discrimination features (i.e., the shape and position of sternite 8 and gonopophysis 9) are still obscured. Based on the observable features at hand, we believe that Vetosmylus gen. nov. should be excluded from Kempyninae due to its single row of cells between MA and MP in both fore- and hind wings. Kempyninae typically have more than one row of cells between MA and MP. Therefore, the new genus can be attributed to Osmylinae as the earliest record of this subfamily.

Comparing with the known osmyline genera of Osmylus Latreille, 1802 , and Sinosmylus Yang, 1992 , Vetosmylus gen. nov. is distinctly different for the absence of inner gradate series in forewing, as these genera have at least two complete gradate series (Wang and Liu 2009). The new genus can also be distinguished from the other extant genus Parosmylus Needham, 1909 due to the relatively long A1 that exceeds half the length of CuP (cf. A1 is commonly about half the length of CuP in osmyline genera). It is noteworthy that the new genus shows the high similarity with the only fossil osmyline genus Lithosmylus (~34 Mya, Eocene), and in fact only several species-level differences between them can be detected, i.e., the relatively long A2 with about half of CuP length in the new genus (cf. shorter than half of CuP in Lithosmylus , especially in hind wing) and A3 ending at the margin in the new insect (cf. A3 relict and partly coalescent with the proximal branch of A 2 in Lithosmylus ). Considering the huge gap of occurrence times of the fossil genera (~130 Mya), we feel it is appropriate to erect a new genus for the new Middle Jurassic insects, instead of assigning them to the much younger Lithosmylus .

Stratigraphic and geographic range. —Jiulongshan Formation, Middle Jurassic; Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia, China.