A new fossil silky lacewing genus (Neuroptera, Psychopsidae) from the Early Cretaceous Yixian Formation of China

Abstract A new genus and species, Undulopsychopsis alexi gen. et sp. n., is described from the Early CretaceousYixian Formation of western Liaoning Province, China. This genus is probably most closely related to the Asian Cretaceous genus Kagapsychops Fujiyama, 1978. The family affinity of Undulopsychopsis gen. n. is discussed. The genus is preliminarily assigned to Psychopsidae, although it shares some character states with Osmylopsychopidae (e.g., crossveins are very scarce; Rs1 and 1A are multi-branched).


introduction
The extant Psychopsidae is a small family (five genera and 27 described species), currently restricted to disjunct regions in southern Africa, southeastern Asia and Australia (New 1988;Oswald 1993a;Wang and Bao 2006). Adult psychopsids are recognized by their broad wing shape, dense venation, the presence of vena triplica, spectacularly patterned and hairy wings, which gives psychopsids the common name of silky lacewings (New 1989;Oswald 1993aOswald , 1995. Fossil psychopsids were much more widely distributed than the extant taxa. Since the early 20th century, fossil psychopsids have increasingly been found from all over the world, with species ranging in age from the Triassic to the Tertiary. The earliest fossil record of the Psychopsidae is Triassopsychops Tillyard, 1922 from the Late Triassic of Australia (Tillyard 1922), which possesses a true vena triplica, characteristic of this family. While many fossil psychopsids were recorded from the Mesozoic, few representatives have been described from the Tertiary. Hitherto, 35 fossil species (24 genera) have been referred to Psychopsidae (Table 1). The psychopsid affinity of many Jurassic and Cretaceous genera is debatable. For example, Jepson et al. (2009) believe that some genera (e.g., Grammapsychops Martynova, 1954, Embaneura G. Zalessky, 1953, Pulchroptilonia Martins-Neto, 1997, and Kagapsychops Fujiyama, 1978) may belong to another psychopsoid family, Osmylopsychopidae. The position of these and some other fossil genera from the Mesozoic is questionable, due to certain differences in details of the wing venation between fossil and extant psychopsids (e.g., the pattern of Rs branches, the configuration of M and Cu in the forewing, the structure of vena triplica), although their general venational pattern is similar to that of extant representatives. Furthermore, the combination of a small number of known extant species and the often poor preservation of fossil representatives has greatly hindered the understanding of fossil psychopsids. The ambiguous diagnoses of many fossil psychopsids have resulted in potential confusion with other Mesozoic neuropterans (Andersen 2001;Makarkin and Archibald 2003). More evidence is needed to further the knowledge of fossil psychopsids. In recent years, many Mesozoic psychopsids described from Asia (particularly from Russia and China) have drawn increased attention to fossil psychopsids. In this paper, we describe a new genus and species of Psychopsidae from the Early Cretaceous Yixian Formation of Huangbanjigou Village, Liaoning Province, China.

Material and methods
The specimen described herein is from the Yixian Formation of Huangbanjigou Village, Shangyuan County, Beipiao City, western Liaoning Province, northeastern China. The principal fossil-bearing layers in Huangbanjigou locality are silty mudstone, yellowish to grayish, rich in insects, fish and plants (Chen et al. 2005). The age of these fossil-bearing strata in Sihetun area (including Huangbanjigou) is considered to be well supported by radiometric dating as Early Cretaceous (Middle/Late Barremian), from table 1. Fossil species currently ascribed to the family Psychopsidae.

Species
Age Locality 1 Triassopsychops superbus Tillyard, 1922 Late Triassic (Carnian) Denmark Hill, Queensland, Australia 2 Archepsychops triassicus Tillyard 1919 Late Triassic (Carnian) Denmark Hill, Queensland, Australia 3 Apeirophlebia grandis Handlirsch, 1906 Early Jurassic ( (Wang et al. 2001a;Yang et al. 2007). The specimen is deposited in the Chaoyang Bird Fossil National Geopark, Chaoyang City, Liaoning Province, China. The material was examined using a Leica MZ12.5 dissecting microscope. The photographs were taken using a Nikon D100 digital camera coupled to a Nikkor 105mm macro lens, and final photographs were adjusted by using Adobe Photoshop 4.0 image-editing software. All line drawings were drawn made directly using CorelDraw 12 graphic software.
We follow the traditional (sensu Wootton 2003) venational terminology of Comstock (1918) with the recent interpretation of Oswald (1993b) and Archibald and Makarkin (2006). The abbreviations used in the text are: C, costa; Sc, subcosta; hv, humeral veinlet; R, radius; R1, first branch of R; Rs, radial sector; Rs1, basal-most branch of Rs; M, media; MA, media anterior; MP, media posterior; Cu, cubitus; CuA, cubitus anterior; CuP, cubitus posterior; 1A-2A, first to second anal veins. Etymology. The generic name is derived from the Late Latin undula (meaning a small wave, refers to its undulate wing margins) and Psychopsis (the type genus of the family). The gender is feminine.
Remarks. This new genus differs from all other psychopsids by possessing undulate outer and hind margins of both wings. The combination of the following forewing character states is also characteristic: no costal gradate series; branches of Rs dichotomously branched; the basal-most branch of Rs multi-branched, and M forked far distal to the origin of Rs. The new genus has scarce costal crossveins, which are not arranged in gradate series, in contrast to the genera Grammapsychops, Miopsychopsis Makarkin, 1991, Baisopsychops Makarkin, 1997, Cretapsychops Jepson et al., 2009and Epipsychopsis Makarkin, 2010. Undulopsychopsis gen. n. possesses the dichotomously branched branches of Rs; this condition is also present in the following psychopsid genera: Triassopsychops, Angaropsychops Martynova, 1949, Psychopsites Jepson et al., 2009, Valdipsychops Jepson et al., 2009, Epipsychopsis, Pulchroptilonia, Putzneura Martins-Neto et Rodrigues, 2010 Embaneura. Among these the new genus is most similar to those genera which have the multi-branched Rs1 and M forked far distal to the origin of Rs. This combination is present only in the genus Kagapsychops. The type species of this genus (K. aranea Fujiyama, 1978) is fragmentary and poorly preserved, but K. continentalis Makarkin, 1994 is well-preserved (although incomplete). Undulopsychopsis gen. n. clearly differs from Kagapsychops by being a much smaller size (the forewing of the former is approximately twice shorter than that of the latter), and the absence of the gradate series of crossveins in the radial space. Other fossil psychopsids, for example Propsychopsis Krüger, 1923, Litopsychopsis Engel et Grimaldi, 2008and Micropsychops Jepson et al., 2009 differ strongly from the new genus by having mostly unbranched veins of Rs before end-twigging and several long gradate series of crossveins in the radial space.
Diagnosis. As for the genus. Description. Body: only partial thorax preserved. Pronotum sub-rectangular, 1.2 mm long, 2.8 mm wide, suffused with many long hairs. Mesonotum 3 mm long, 3.5 mm wide, with some long hairs laterally. Forewing (Fig. 3) subtriangular, 21.5 mm long, 12.3 mm wide. Costal space broad throughout; subcostal veinlets forked; humeral veinlet slightly recurrent, branched. Subcostal space much broader than R1 space. R1 space narrow. Sc and R1 close distally but not fused. Rs with 10 primary branches, branches of Rs dichotomously branched; Rs1 pectinately branched with branches directed anteriorly. M appears originating from R, forked far from origins of Rs1. MA and MP probably simple (their terminal parts not preserved). Cu forked near wing base. CuA pectinately branched distal to fork of M. CuP multi-branched, dichotomous. Anal area well-developed. 1A long, dichotomously branched. 2A multi-branched (incompletely preserved). Only few crossveins detected: costal space basally with scarce crossveins, not forming gradate series; subcostal space with 4 crossveins preserved; R1 space with 5 crossveins preserved; medial space with 2 crossveins preserved. Veins covered with dense hairs, particularly long basally. Trichosors distinct. Wing membrane in general brownish; colour pattern consists mainly of two pale transverse zigzagged bands which are proximally darker than other portions of wing; indistinctly mottled basally and apically. Wing margin haired; hind and outer margins undulate.
Hind wings almost entirely hidden under forewing, about 16.5 mm long as preserved, 10 mm wide. Venation very poorly preserved; no details visible. Outer margin undulate.
Etymology. The specific name is named in honor of the distinguished Russian paleoentomologist Prof. Alexandr ('Alex') Rasnitsyn.

Discussion
Based on the configuration of the venation in the radial space of the forewing, fossil psychopsids can be divided into two groups. One group includes the taxa with simple branches of Rs, the majority of which are not branched before end-twigging. This group is represented by the genera Propsychopsis, Baisopsychops, Cretapsychops, Micropsychops and Litopsychopsis. The crossveins in these genera are usually arranged in one to two   gradate series in the costal space, and two to four long gradate series in the radial space. They occur in the Cretaceous and Eocene; all extant genera belong to this group as well.
The other group includes the taxa which have the branches of Rs dichotomously branched, and often the basal-most branch of Rs multi-branched. Representative genera of this group are the earliest psychopsid Triassopsychops, and other Mesozoic psychopsids, e.g., Angaropsychops, Grammapsychops and Kagapsychops (see complete list above). They possess numerous radial crossveins, arranged in many short gradate series (often irregular), and usually no costal gradate series. Undulopsychopsis gen. n. belongs to the latter group. It is preliminarily assigned to Psychopsidae, as its Sc and R1 are not fused apically, and the costal space is broad, although it almost lacks crossveins. The latter feature, and the multi-branched Rs1 and 1A are shared by this genus with another Mesozoic psychopsoid family Osmylopsychopidae (especially with its type genus) known from the Triassic of Australia and Central Asia (Lambkin 1992;Shcherbakov 2008). However, in the family Osmylopsychopidae Sc and R1 are clearly fused apically. Some genera currently ascribed to Psychopsidae also have venation similar to that of Osmylopsychopidae (e.g., Sinopsychops Hong, 1982;Grammapsychops). Unfortunately, the majority of these are either fragmentary or incompletely described and are in need of re-examination. Therefore, until the revision of psychopsoids has been completed, we consider all species enumerated in Table 1 as tentatively belonging to Psychopsidae.
Previously, only four species have been recorded from the Mesozoic of China, i.e., Angaropsychops sinicus Hong in Wang, 1980 (probably from the Early Cretaceous Yixian Formation), Sinopsychops chengdeensis Hong, 1982, Beipiaopsychops triangulatus Hong, 1983, and Cretapsychops decipiens Peng et al., 2010 (all from the Middle Jurassic Jiulongshan Formation). Undulopsychopsis gen. n. is the fifth representative of the Chinese psychopsids found from the different locality (Huangbanjigou). It is characterized by the undulate wing margin, a unique character state among known Psychopsidae, and the forewing venation that is not typical for this family compared with most other genera of Psychopsidae.