New Fossil Lepidoptera (Insecta: Amphiesmenoptera) from the Middle Jurassic Jiulongshan Formation of Northeastern China

Background The early history of the Lepidoptera is poorly known, a feature attributable to an inadequate preservational potential and an exceptionally low occurrence of moth fossils in relevant mid-Mesozoic deposits. In this study, we examine a particularly rich assemblage of morphologically basal moths that contribute significantly toward the understanding of early lepidopteran biodiversity. Methodology/Principal Findings Our documentation of early fossil moths involved light- and scanning electron microscopic examination of specimens, supported by various illumination and specimen contrast techniques. A total of 20 moths were collected from the late Middle Jurassic Jiulongshan Formation in Northeastern China. Our principal results were the recognition and description of seven new genera and seven new species assigned to the Eolepidopterigidae; one new genus with four new species assigned to the Mesokristenseniidae; three new genera with three new species assigned to the Ascololepidopterigidae fam. nov.; and one specimen unassigned to family. Lepidopteran assignment of these taxa is supported by apomorphies of extant lineages, including the M1 vein, after separation from the M2 vein, subtending an angle greater than 60 degrees that is sharply angulate at the junction with the r–m crossvein (variable in Trichoptera); presence of a foretibial epiphysis; the forewing M vein often bearing three branches; and the presence of piliform scales along wing veins. Conclusions/Significance The diversity of these late Middle Jurassic lepidopterans supports a conclusion that the Lepidoptera–Trichoptera divergence occurred by the Early Jurassic.


Introduction
The Lepidoptera, or butterflies and moths, are one of the most speciose lineages of herbivores, currently including about 157,500 described species encompassing the four suborders of Zeugloptera, Aglossata, Heterobathmiina, and Glossata [1]. In contrast to the documented paleodiversity of otherdiverse insect lineages [2], the Lepidopteran fossil record is depauperate [3]. Only two extant suborders, Zeugloptera and Glossata, and an extinct suborder, Eolepidopterigina proposed by Rasnitsyn [4], are represented in the fossil record. Speciosity of the basal lepidopteran lineages is minimal in the fossil record, as in the extant fauna. This may be a consequence of the Lepidoptera once constituting a minor group of the world's fauna, following their evolution from the stemgroup, the Amphiesmenoptera (Fig. 1A) [5], a major holometabolan lineage comprising two distinctive insect orders, the Lepidoptera and the Trichoptera. The taxonomic boundary between Lepidoptera and Trichoptera is often obscured in their early fossil record [3], attributable to an overall morphological similarity and presence of few apomorphic characters visible in fossil specimens [5].
The earliest unequivocal lepidopteran fossil hitherto established is Archaeolepis mane Whalley, 1985 (Fig. 1B) from the Early Jurassic, about 190 million years ago (Ma), of Dorset, England [5,18,19]. The next, more recent, early fossils are eight non-monophyletic genera, dated to approximately 180 Ma, from the uppermost Lias of Dobbertin, Germany [5], which were described by Handlirsch as Necrotauliidae. However, Ansorge [21,22] disputed the necrotaulid affiliations of the Handlirsch's specimens and other well-preserved wings from the Grimmen locality of Germany, and assigned most of these to the Lepidoptera on the basis of the 3branched M vein and the presence of scales on the forewings. These fossils overwhelmingly are represented by wings. A representative forewing is shown in Fig. 1C, indicating a M with 3 branches and the M 1 , separated from the M 2 at an angle of about 70 degrees, and sharply angulate at the junction with crossvein r-m. Additionally, a forewing of Undopterix sukatshevae, within the Undopterigidae [23], is shown in Fig. 1D, as is a forewing of Netoxena nana in the Eolepidopterigidae [3,24], in Fig. 1E. Huang et al. [25] described Mesokristensenia sinica in the Mesokristenseniidae, the forewing of which is shown in Fig. 1F. For comparison, the forewing of a trichopteran, Juraphilopotamus lubricus Wang, Zhao & Ren, 2009 [17], is shown in Fig. 1G.
? Necrotaulius Handlirsch, 1906 N. tener Sukatsheva, 1990 K1 Russia [50,60] 164-165 Ma [26], a date supported by slightly younger isotopic dates from overlying volcanic deposits [26,27]. This date corresponds to the Callovian-Oxfordian boundary interval of the latest Middle Jurassic, using the most recent, standard international time scale [28]. The deposit contain beautifully preserved fossils of insects and other animals [29][30][31][32][33]. After comparison of these fossils to other Mesozoic lepidopteran specimens, we recognized below eleven new genera and fourteen new species, assigned to the three families, the Eolepidopterigidae, the Mesokristenseniidae, and the Ascololepidopterigidae fam. nov. We used additional taxa to emend diagnoses of the two previously named families, the Eolepidopterigidae and the Mesokristenseniidae. With the fossils reported by Huang et al. [25], these new findings, now document the third oldest-known lineage of lepidopterans.

Materials and Methods
Light Microscopy, Image Processing and Line Drawings All specimens were microphotographed and illustrated using a Leica MZ12.5 dissecting microscope accompanied with a drawing tube attachment in Beijing, and an Olympus SZX12 stereomicroscope in Washington, DC. Images were captured using dissecting microscopes equipped with digital cameras and image processing software. The image processing software for the Beijing computer-microscope-camera system was a Nikon DXM 1200C, with NIS-elements D 2.30; and in Washington, DC, an Image-Pro 6.1 (Media Cybernetics) platform. Alcohol was used to increase the contrast of specimen structures for some images. Line drawings in Beijing were made in conjunction with Photoshop CS2 graphic software.

Electron Microscopy
We used a Philips XL30 environmental scanning electron microscope to examine shrink-wrapped specimens. Compression fossils, such as the material studied herein, generally present minimal topographic relief. This absence of microtopographic differentiation and the uncoated state of the specimens, posed a demand on specimen imaging. By varying the microscopy conditions for each specimen, including sources of illumination, such as back-scattered electrons, gas emission secondary electrons and particle detector adjustment; or alternatively, varying microtopographic aspect, spot size or accelerating voltage; we strove to find the best combination of imaging conditions within a challenging SEM environment.
The fossil specimens studied under vacuum conditions of the electron microscope necessitated a modification of specimen preparation. The presence of a poorly consolidated sedimentary matrix surrounding the fossils resulted in the spalling of particles that interfered with normal operation of the vacuum tube. A protocol was devised that solved this problem. Any matrix material that sloughed from the specimen was isolated by heat-resistant polyalfin film, used in industrial kitchens to shrink-wrap food. In contrast to polyester shrink-wrap, polyalfin film does not melt or release gas in the vacuum chamber. The shrink-wrapping of stubmounted specimens in polyalfin film reduced the likelihood of costly specimen chamber contamination. Thereafter, the wrapping was carefully heat-sealed to reduce specimen bulk and promote ease of further examination. When the specimen was ready for microscopy, a window was opened over the area of interest by careful cutting of the wrapping, leaving a hole for specimen access. A thorough dusting of particles attached to the wrapping is necessary immediately preceding insertion of the specimen into the specimen chamber, particularly if the fossil has remained in storage for some time.

Measurement and Anatomical Conventions
Measurements, including body length and width, wing length and width, and wing index, follow Kristensen and Nielsen [34]. The wing index is defined as the ratio of wing width/wing length. All measurements are given in millimeters (mm). Amphiesmenopteran and lepidopteran apomorphies are taken from Kristensen and Skalski [15] and Huang et al. [25]. Family-level classification follows Nieukerken et al. [1]. Wing venation nomenclature is based on Wootton [35]. A proposed hypothetical forewing for Lepidoptera, modified from Kristensen and Skalski [15], is illustrated in Fig. 2A. In contrast, a hypothetical forewing for Trichoptera, modified from Holzenthal et al. [36], is presented in Fig. 2B. Wing veins are given as combinations of vein abbreviation and the number of vein branches. For example, Rs-4 means that the Rs has four branches; Sc-1/2 indicates that the Sc has one or two branches. Wing vein forking of branches are described as occurring at the same level (equidistant) or at a different level (variable distance) from the base of the wing. The Lepidoptera ovipositor is defined as a composite of abdominal segments VIII, IX+X and associated intersegmental membranes. Additional abbreviations of morphology are provided in the figure captions.

Etymological Sources
The primary source for Latin and Greek etymology is Simpson [37], buttressed by Brown's compendium [38]. Linnaean designations of genus and species names were configured to be consistently either Latin or Greek, avoiding combinatorial forms with both languages in the same word.

Nomenclatural Acts
The electronic edition of this article conforms to the requirements of the amended International Code of Zoological Nomenclature, and hence the new names contained herein are available under that Code from the electronic edition of this article. This published work and the nomenclatural acts it contains have been registered in ZooBank, the online registration system for the ICZN. The ZooBank LSIDs (Life Science Identifiers) can be resolved and the associated information viewed through any standard web browser by appending the LSID to the prefix ''http://zoobank.org/''. The LSID for this publication is: urn:lsid:zoobank.org:pub: AC86AB61-87FC-4353-96BB-AA03231E3BA5. The electronic edition of this work was published in a journal with an ISSN, and has been archived and is available from the following digital repositories: PubMed Central, LOCKSS (www.lockss.org).  Rasnitsyn, 1983. Family Eolepidopterigidae Rasnitsyn, 1983. Type genus. Eolepidopterix Rasnitsyn, 1983 [4]. Emended diagnosis. Head with mandibulate mouthparts. Antennae filiform, less than half the length of forewing. Pronotum longer than one third the mesonotum length. Foretibia with an epiphysis. Mesotibia with one pair of spurs; metatibia with two pairs of spurs. Both pairs of wings homoneurous (the venation of the forewings and hind wings alike). Wings covered with scales. Forewing with jugum and number of vein branches as follows: Sc-1/2, R 1 -1/2, Rs-4, M-3, CuA-2, CuP-1, and A-2/3. Ovipositor with long apophyses anteriores; papillae anales long, non-piercing.

Taxonomy
The synapomorphies for the Eolepidopterigidae are the mesotibia with a pair apical spurs, metatibia with a pair medial spurs and a pair apical spurs, wings homoneurous, forewing M vein 3-branched, and ovipositor with long apophyses anteriores.
This family is defined as a clade in Amphiesmenoptera, which have three branches of the M vein in the hind wing and the anterior margin of female abdominal segments VIII and IX with long, rod-like apodemes. This family can be assigned to Lepidoptera by the following characters: foretibia with an epiphysis, mesotibia lacking medial spurs, wings covered with scales, and forewing M vein 3-branched.
Distribution  [7] unconvincing due to lack of definitive apomorphies. Subsequently, Nieukerken et al. [1] placed only E. jurassica in the Eolepidopterigidae. We assign all the above-mentioned genera to this family for the following reasons. Skalski erected the genus Undopterix in Micropterigidae [10], with the type species as U. sukatsheva Skalski 1979. Another supposed congener was added, U. caririensis Martins-Neto & Vulcano, 1989 from the Crato Formation, Brazil [10,39]. The taxonomic position of this genus is controversial: some authors have placed it in Micropterigidae [10]; some assign it to the Undopterigidae [16]; whereas others considered it as Eolepidopterigidae [4,7]. Yet, Undopterix sukatsheva Skalski, 1979, exhibits no autapomorphies of the Micropterigidae [34]. The long apophyses of the last several abdominal segments are comparable to those present in the Eolepidopterigidae [4]. For wing venation, Undopterix shows similarity to Eolepidopterigidae, especially in the hind wing. Undopterix has R 1 forked, which is rare in Micropterigidae, but present in some members of Eolepidopterigidae, such as Daiopterix Skalski [23], Seresilepidopteron gen. nov., Akainalepidopteron gen. nov., Quadruplecivena gen. nov., and Petilicorpus gen. nov. Consequently, we believe it is more appropriate to place Undopterix in the Eolepidopterigidae. We agree with Skalski [7], followed by Sohn et al. [3], in considering the Undopterigidae a synonym of the Eolepidopterigidae. In addition, the Eolepidopterigidae are believed to have affinities with the Agathiphagidae [7], based on an ovipositor bearing long apophyses that is not present in Micropterigidae and Heterobathmiidae [34]. When Gracileopterix was erected, it was not assigned to a family [39], and because of its great similarity to Undopterix, we tentatively place this genus in Eolepidopterigidae.
Etymology. The generic name, Seresilepidopteron, is derived from the Greek, Seres (Sgrez), the ancient Greek (and later similar Latin) name for northwestern China and its inhabitants, also referring to the land where silk originates; and lepidos, the Greek word for ''scale'' or ''flake''; and pteron, Greek, for ''wing'' or ''fin.'' The root, lepido, also refers to the Lepidoptera, the ordinal affiliation of this genus. The gender is masculine.
Diagnosis. Mesothorax slightly longer and wider than metathorax. All legs lacking spines. Forewing Sc and R 1 forked, all furcations of Rs 1+2 , Rs 3+4 and M 1+2 at the same level with each other. Humeral vein, sc-r crossvein and crossvein between R 1 and Rs present; three anal veins looping into a double-Y configuration; jugum present but short, lacking long setae. Hind wing Sc not forked; R 1 forked; sc-r crossvein present.
Distribution. Inner Mongolia Autonomous Region, China.
Comparison. The venation of Seresilepidopteron resembles that of Daiopterix, but Seresilepidopteron differs from the latter by three anal veins looping into a double-Y configuration (vs. only two anal veins looping into a single-Y configuration). Seresilepidopteron resembles Undopterix, but it differs from the latter by: 1), having sc-r and r crossveins (vs. lacking sc-r and r crossveins); 2), the presence of three anal veins; and 3), a double-Y configuration in the forewing (vs. two anal veins). Etymology. The specific name is derived from the Latin, dualis (dual, twice).  segmented. Midleg (Figs. 3G, K) well preserved, covered with dense hairs, but detached ca. 5.0 mm from the insect. Tarsi 5segmented, with spines; apical segment with a pair of tarsal claws. A pair of apical spurs apparent on the mesotibia (Fig. 3K). Femur of hindleg robust, detached (Figs. 3H, L); ca. 3.1 mm apart from the posterior margin of metathorax.
Forewing ( Fig. 3C) with a humeral vein; costal margin bearing sparse cilia. Sc forked, stalked, gently curved; Sc 2 reaching proximal margin of pterostigma. R 1 forked, both branches of R 1 extend to pterostigma. Rs 4-branched; Rs 4 to the apex of forewing; Rs 1+2 , Rs 3+4 , and M 1+2 furcations arise at same level in the wing. Crossvein sc-r oblique, proximal to the R 1 -Rs furcation. Crossvein r located midway between R 1 furcation and Rs furcation. M 3-branched, the hyaline zones surround the r-m crossvein at Rs 1+2 , Rs 3+4 and M 1+2 furcations. CuA bifurcated; CuP simple, slightly curved terminally. Stem of M divergent from stem of R basally, just beyond humeral vein. CuA divergent from M slightly beyond R-M furcation; R forks just after M-CuA furcation. Three anal veins looping into a double-Y configuration. Crossvein between 1A and 2A present. A short, digitate jugum present in the basal posterior margin of forewing, lacking long setae. Hind wing venation ( Fig. 3C) resembles forewing except Sc not forked; sc-r crossvein present proximally to R 1 furcation. Costal margin bears long bristles. Anal area poorly preserved.
Wing venation (Fig. 4B) of female similar to male, except for the following differences: 1), Sc 2 extends to anterior wing margin at midlength in male, after midlength in female; 2), R 1 furcation in female closer to the apex than that in male; 3), in female, crossvein between R 1 and Rs located before Rs furcation on right wing, but in male after Rs furcation; 4), in female, cup-a crossvein present but no crossvein in anal area; and 5), in male, cup-a crossvein absent, but crossvein in anal area present in the female.
Measurements Remarks. Because there are many similarities in provenance and morphology between these two specimens from the same locality, we consider these two specimens to be conspecific male and female. The minor differences in the wing venation between male and female could be attributable to either individual variation or sexual dimorphism.
Etymology. The generic name Akainalepidopteron is derived from the Greek akaina, (spine, thorn), referring to the piliform scales on the hind wing veins of this species; and ''lepidos,'' the Greek name for ''scale'' or ''flake''; and ''pteron,'' Greek for ''wing'' or ''fin.'' The root, lepidos, also refers to the Lepidoptera, the ordinal affiliation of this genus. The gender is masculine.
Distribution. Inner Mongolia Autonomous Region, China.
Diagnosis. Mesotibia with few short spines; metatibia with robust spines. Forewing and hind wing bear cilia on the anterior margin. Humeral vein present in forewing. Sc and R 1 forked; all furcations of Rs 1+2 , Rs 3+4 , and M 1+2 ca. at same level with each other. Hind wing Sc not forked. R 1 forked; furcations of Rs 1+2 , Rs 3+4 , and M 1+2 almost at the same level. Long, piliform scales present on several veins of hind wing. Crossvein cua-cup present.
Comparison. The diagnostic autapomorphy of Akainalepidopteron consists of piliform scales present on the veins of the hind wing, a character not known to exist for any other lepidopteran fossil species. Akainalepidopteron exhibits a great similarity to Seresilepidopteron in venation, but differs in the position of some crossveins. The differences are: 1), in the forewing, Akainalepidopteron lacks sc-r and r crossveins (vs. retention of these crossveins); 2), in the hind wing, the cua-cup crossvein is present in Akainalepidopteron (vs. absence); and 3), the sc-r crossvein is absent in Akainalepidopteron (vs. presence).
Akainalepidopteron also is similar to Daiopterix, especially to D. olgae that has wing cilia and metatibial spines. Akainolepidopteron is distinguished from Daiopterix by the following characters: 1), the cup-a 1 crossvein is absent in Akainalepidopteron (vs. present); and 2), the humeral vein is present in Akainalepidopteron (vs. absent).
Compared with Undopterix, Akainalepidopteron is different in that: 1), it has forking of Rs 1+2 at the same level as forking of Rs 3+4 (vs. a stem Rs 1+2 only half length of the stem Rs 3+4 ); 2), the anterior margin of forewing and hind wing bears cilia in Akainalepidopteron (vs. lacking cilia); and 3), the metatibiae has spines in Akainalepidopteron (vs. lacking spines). Etymology. The specific name is derived from the Greek, elachys (short, small), and pteron (wing, fin), referring to the wing of this species that is shorter than its body length.
Type materials. Holotype: CNU-LEP-NN-2012-024; R; well preserved fore and hind wings; anal area covered by body and portions of the legs. Paratypes: CNU-LEP-NN-2012-023; R; well preserved legs; anal area covered by body and part of hind wing; and CNU-LEP-NN-2012-026; sex unknown; a well preserved forewing; anal area poorly preserved.
Locality and horizon. These specimens were collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary.
Diagnosis. Same as generic diagnosis.
Description. Head length subequal to width, invested with dense setae on the anterior margin. Antennae filiform, tapered to apex; length of segments equal to their diameter. Eyes oval, with sparse setae on the outer margin.
Forecoxae more robust than forefemora; femora ca. 1.6 times as long as foretibiae, slightly longer than foretarsi. Epiphyses indiscernible. Mesocoxae more slender than forecoxae; mesofemora longer than mesotibia; two long spines present at the end of mesofemora; mesotibia with spines. Metafemora robust and short, less than half the length of metatibia; metatibia with irregularly arranged spines at the distal part, and with one pair medial spurs and one pair apical spurs. All tarsal segments with terminal spinules.   Remarks. There are three forms of wing-coupling in Lepidoptera: the jugate, frenate and amplexi conditions. The frenular bristles on the anterior margin of the hind wing of CNU-LEP-NN-2012-024 (Fig. 5C) probably played an important role in wing-coupling. Because the jugum is not discernible in these specimens and the female possesses multiple frenular bristles, we believe that this species probably possessed a modified jugatefrenate form of wing-coupling.
Etymology. The generic name is derived from the Greek, dynamis (power, strength), referring to the robust hind leg of this genus; and lepidos, Greek for ''scale'' or ''flake,'' also referring to the ordinal name, Lepidoptera, to which this genus belongs; and pteron, meaning ''wing'' or ''fin'' in Greek. The gender is masculine.
Distribution. Inner Mongolia Autonomous Region, China. Diagnosis. Body relatively large, ca. 7 mm long. Metatibia robust, with strong spines. Forewing and hind wing lack cilia on the anterior margin. Humeral vein present in forewing. Sc and R 1 forked; all furcations of Rs 1+2 and Rs 3+4 veins at same level. Hind wing lacking spines.
Comparison. Dynamilepidopteron is similar to Akainalepidopteron in venation, but: 1), the former lacks cilia on the anterior wing margins (vs. both forewing and hind wing with cilia); and 2), the hind wing lacks spines on the veins (vs. spines present on the veins).
Etymology. The specific name is derived from the Latin, aspinosus (the absence of spines), in reference to the hind wing lacking spines.
Locality and horizon. This specimen was collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary.
Diagnosis. Same as generic diagnosis.
Description. Head short and broad, possibly due to preservation. Antennae filiform; length of segments equal to their diameter basally, the length ca. 1.5 times as long as their diameter distally. Maxillary palpus visible, obtuse aspect apically. Mesoscutum broader than long, posterior edges of mesoscutum concave along midline; mesoscutellum flabellate, relatively large, nearly equal to mesoscutum in length; metascutum dumbbell shaped; metascutellum smaller than mesoscutellum. Metatibia relatively robust; with irregularly arranged spines, bearing two pairs of spurs, one pair apically and the other pair arising slightly beyond middle of tibia; all spurs ca. 1.5-2 times as long as diameter of tibia. Metatarsi 5-segmented; tarsomere I longest, nearly equal to the total length of tarsomeres II, III, IV and V combined; two spinules at the apex of each tarsomere.
Forewing 2.8 times as long as wide. Humeral vein present. Sc forked from 2/5 of the stem length; Sc 1 , extending midway along costal margin; Sc 2 beyond 2/3 the length of the wing from its base. R 1 forked distally, slightly beyond Rs 1+2 furcation; Rs 4-branched; Rs 4 terminating slightly below the apex of forewing; Rs 1+2 stalked ca. 0.3-0.4 of their total length; Rs 3 and Rs 4 free; stem Rs 1+2 subequal in length to stem Rs 3+4 . M 3-branched. CuA bifurcated; CuP not preserved. Three anal veins looping into a double-Y configuration.
Measurements (in mm). Body length 7.0; width 1.9. Etymology. The generic name, Quadruplecivena, is derived from the Latin, quadruplex (quadruple, fourfold); and vena (vein, blood vessel); which jointly refers to the costal margin of hind wing that consists of a Sc, sc-r 1 crossvein and a R 1a , forming a quadrate configuration. The gender is feminine.
Etymology. The specific name is derived from the Latin celsa (eminent, noble) in reference to the labial palpi, which are prominent and resemble a crown, providing a noble or regal appearance.
Type material. Holotype: CNU-LEP-NN-2012-027; =; consisting of a well-preserved head, with antennae and labial palpi; well-preserved legs. Left fore-and hind wings overlapping. The right fore-and hind wings are partially preserved; the anal area is poorly preserved. The left hind wing is unusually longer than the right hind wing, probably due to deformation of the matrix or actual wing asymmetry of this particular individual.
Locality and horizon. This specimen was collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary. Diagnosis. Same as generic diagnosis. Description. Male. Antennae filiform, tapered to apex, ca. 1/3 as long as forewing; length of segments shorter than their diameter basally, subequal to their diameter distally. Compound eyes bearing long sparse setae. Labial palpi 3-segmented (Fig. 9A), the last two segments nearly equal in length; apical palpal segments tapered toward apex. Mesothorax with large prescutum; anterior and posterior edge of mesonotum distinctly concave along midline; mesoscutellum triangular. Foretibial epiphysis indistinct. Mesotibia with one pair of apical spurs (Fig. 9B). Metatibia with one pair of medial spurs and one pair of apical spurs (Fig. 9C). Metatarsi 5-segmented, tarsomere I ca. 1.9 times as long as tarsomere II; tarsomere II ca. 1.6 times as long as tarsomere III; tarsomere III subequal to tarsomere IV, and slightly longer than tarsomere V. All tarsal segments lacking terminal spinules.
Forewing 3 times as long as wide; anterior margin bearing cilia. Humeral vein present. Sc forked. Rs 4-branched; Rs 1+2 stalked ca. 0.2 of their total length; Rs 1+2 forked at the same level as Rs 3+4 furcation; Rs 4 and M 1 respectively above and below wing apex. M 3-branched; M 1 and M 2 stalked; M 1+2 forked beyond Rs 3+4 furcation. CuA bifurcated. Anal veins not preserved. In hind wing, Sc not forked. R 1 forked; crossvein sc-r 1 present and slightly curved and oblique, originating near end of Sc and terminating near R 1 furcation; Rs 4-branched; stem Rs 1+2 slightly longer than Rs 3+4 . M 3-branched; M 1+2 forked beyond Rs 3+4 furcation; M 3 curved at 2/3 the length of vein M 3 from its base. CuA bifurcated. Etymology. The generic name is derived from the Latin petilis (thin, slender), and corpus (body, substance), which collectively refers to the gracile body shape of this species. The gender is masculine.
Comparison. Petilicorpus gen. nov. is assigned to the Eolepidopterigina for having a long apophyses in the abdomen and the M vein 3-branched in the forewing. Petilicorpus resembles Eolepidopterix in having the presence of a slender body and similar forewing length and antennal length. However, Petilicorpus differs from Eolepidopterix in the following characters: 1), the pronotum is short with a length of 0.05 mm and a width/length ratio of 8.0 (vs. pronotum relatively long with length of 0.19 mm and width/ length ratio of 2.9); 2), the Sc vein is forked distally (vs. the Sc vein branching near the base of the forewing); and 3), the anterior margins of both the fore-and hind wings bear cilia (vs. lacking cilia). The wing of Paleolepidopterix is not well preserved. Based on the present specimen, Petilicorpus can be differentiated from Paleolepidopterix by its longer head and shorter pronotum. The venation of Petilicorpus resembles Daiopterix in the following characters: 1), the Sc and R 1 are forked; and 2), the Rs 1+2 stem is shorter than the Rs 3+4 stem. In addition, Petilicorpus can be separated from Daiopterix by: 1), possession of a long Sc vein (vs. a short Sc vein); 2), the Sc 2 vein extending beyond the Rs 1+2 furcation (vs. the Sc 2 not reaching the Rs 1+2 furcation); and 3), the m crossvein is present (vs. m crossvein absent).
Etymology. The specific name is derived from the Latin, cristatus (bearing a crest, cluster of plumes), in reference to setae on the head.
Locality and horizon. This specimen was collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary.
Diagnosis. Same as generic diagnosis. Description. Female. Body slender and entirely covered by setae. Head slightly longer than wide, anterior edge with clusters of setae pointing forward. Antennae filiform, less than half length of forewing; length of segments equal to their diameter. Eyes oval. A pair of chaetosemata present near eyes (Fig. 10B). Median ocellus absent. Prothorax much broader than length, with a pair of transverse structures that are adjacent mesially. Mesoscutum broader than long, posterior edge concave along midline; mesoscutellum flabellate, slightly shorter than mesoscutum. Mesothorax large. Long setae present on the sides of prothorax and mesothorax.
Anterior margins of both fore-and hind wings bear cilia. Forewing humeral vein indiscernible. Sc forked from distal 1/3 of the stem; Sc 1 extended to the costal margin beyond the 1/3 the length of the wing from its base; Sc 2 extended beyond the 1/2 length of the wing from its base. R 1  Etymology. The generic name is derived from the Latin, longus (long, extended), and capitalis (head of a living creature), in reference to the elongate head of this species. The gender is masculine.
Distribution. Inner Mongolia Autonomous Region, China. Diagnosis. Head longer than wide. Metatibiae lacking spines. Anterior margin of wings lacking cilia. Humeral vein in forewing present. Sc forked. R 1 not forked. All furcations of Rs 1+2 , Rs 3+4 , and M 1+2 almost at the same level with each other. Anal veins looping into a double-Y configuration. Hind wing with Sc and R 1 not forked. Veins on hind wing lacking spines.
Comparison. The venation of Longcapitalis resembles that of other Eolepidopterigidae, but this new genus lacks a R 1 furcation in the forewing, making it different from all other species of Eolepidopterigidae. Longcapitalis shows great similarity to the genus Undopterix, but it differs from the latter in the following characters: 1), the R 1 is not forked in both fore-and hind wings (vs. R 1 forked in the fore-and hind wings); 2), the Rs 1+2 stem is as long as the Rs 3+4 stem (vs. the Rs 1+2 stem shorter than the Rs 3+4 stem); and 3), the anal veins form a double-Y loop (vs. the anal veins forming a single-Y loop). Longcapitalis differs from Akainalepidopteron by the following characters: 1), the R 1 is not forked in both fore-and hind wings (vs. R 1 forked); 2), the hind wing lacks spines (vs. spines present on several veins on hind wing); 3), the wings lack cilia (vs. cilia present on anterior margins of the fore-and hind wings); and 4), the metatibiae lack spines (vs. the metatibiae bearing irregularly arranged spines).
Etymology. The specific name is derived from the Latin, excelsus (tall, large), in reference to the comparatively large body size of this species.
Locality and horizon. This specimen was collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary.
Diagnosis. Same as generic diagnosis. Description. Head relatively long (ca. 0.9 mm), longer than wide; compound eyes elongate oval. Mesonotum slightly broader than long, with median suture; posterior edge concave along midline; mesoscutellum small, ca. half length of mesoscutum. Metafemora with a spine at the end of femora. Metatibiae with one pair medial spurs and one pair apical spurs. Metatarsi 5segmented, all tarsal segments with terminal spinules.
Forewing 2.7 times as long as wide, bearing a humeral vein; pterostigma present. Sc forked, at distal 2/5 of the stem, Sc 1 , almost extending to the midpoint of wing costal margin; Sc 2  An Eolepidopterigidae affiliation is supported by: 1), antennae less than half the length of forewing; 2), M 3-branched; and 3), crossvein absent between Sc and R.
Grammikolepidopteron resembles one fossil species within Micropterix, Micropterix pervetus Cockerell, 1919 [42]. However, Grammikolepidopteron differs from M. pervetus in: 1), the forewing having Sc and R 1 veins that are not forked (vs. Sc and R 1 that are forked); 2), anal veins that form a double-Y configuration (vs. 1A and 2A veins that are parallel); and 3), presence of a CuP vein (vs. absence of the CuP vein).
Etymology. The specific name is derived from the Latin, extensus (outstretched, extended), in reference to the expansive forewings.
Type material. Holotype: CNU-LEP-NN-2012-006P/C (part and counterpart); R; right forewings well preserved; body and hind wing not well preserved. Forewings asymmetrical; left forewing and right hind wing are much longer and slender than the right forewing and left hind wing. This asymmetry probably is attributable to sediment deformation.
Locality and horizon. This specimen was collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary.
Diagnosis. Same as generic diagnosis.
Description. Antennae with scape swollen; flagellum filiform; length of segments equal to their diameter. Eyes relatively small. Last segment of a maxillary (or labial) palpus visible. Posterior edge of mesoscutum concave; mesoscutellum small, half the length of mesoscutum. Metatarsi 5-segmented, tarsomere I longest, almost subequal to the total length of tarsomeres II, III, IV and V combined. Female genitalia with long ovipositor partially preserved.
Forewings distinctly narrow and elongate, slightly rounded apically, ca. 3.6 times as long as wide. Sc not forked, extending to costal margin of wing, at 2/3 the length of wing from base. R 1 not forked, extending to costal margin of wing at a point 4/5 length of wing from base; Rs 4-branched; Rs 3 terminating slightly before wing apex; branching points of R 1 and Rs 1 to Rs 3 linearly aligned. The synapomorphies for the Mesokristenseniidae are mesotibia with only an apical spur, wings homoneurous, R 1 unforked, M vein 4-branched, and ovipositor with anterior apophyses.
The lepidopteran affiliation of this family has been established by Huang et al. [25] based on the following characters: 1), apex of the foretibia with at most one spur; 2), wings covered with overlapping scales; 3), wings lacking nygmata; and 4), the M 1 sharply angulate at the junction with r-m crossvein.
Genera included. Description of additional specimen. Antenna with the scape prominently swollen and pedicel relatively large; flagellum filiform; length of segments equal to their diameter. Compound eyes moderately developed. Apex of labial palpi acute. Mesothorax large; mesonotum slightly broader than long, posterior edge concave; mesoscutellum small, half the length of mesoscutum. Mesofemora and metafemora robust. Metatibia with irregularly arranged spines; a pair of apical spurs and additional spurs arising from distal third or fourth of tibia; all spurs ca. 2 times diameter of tibia. Metatarsi 5-segmented; tarsomere I longest, with short spine. Remarks. This specimen, collected from the same locality as the holotype of M. sinica, matches the characters of M. sinica in the venation, wing index and body size. We deem this specimen conspecific with M. sinica.
Locality and horizon. This specimen was collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary.
Description. Compound eyes oval; antennae filiform; scape large and elongate, with setae distally placed (Fig. 14B); pedicel longer than one segment of flagellum; flagellum slender, the length of segments basally ca. 0.5 times as long as their diameter; length equal to their diameter distally. Metatibia with one pair of medial spurs, ca. 3 times as long as the diameter of the tibia; one pair of apical spurs, ca. 1.5 times as long as the diameter of the tibia; metatarsi 5-segmented, tarsomere I longest. Ovipositor relatively long and robust. Forewing  Etymology. The generic name is derived from the Greek, combining klados (twig, branch, stem), in reference to the presence of crossvein sc-r; and lepidos, meaning ''scale'' or ''flake,'' also signifying assignment to the order Lepidoptera; and pteron, the word for ''wing'' or ''fin.'' The gender is masculine.
Etymology. The specific name is derived from the Latin ovum (egg, egg-like); and formis, (shape of, likeness, form), in reference to the pair of oval structures on the prothorax.
Locality and horizon. This specimen was collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary.
Description. Body slender. Compound eyes rounded. Antenna filiform, slender, length of segments 1.5 times their diameter.
Prothorax relatively large, with a pair of oval, slightly transverse structures that are adjacent mesially (Fig. 15C). Mesothorax with relatively large prescutum; mesoscutum broader than long; mesoscutellum small, posterior edge concave along midline, slightly shorter than mesoscutum. Mesoscutellum fan-shaped; metascutum dumbbell shaped; metascutellum relatively large and broad. Mesofemora ca. 2 times as wide as mesotibia; mesofemora and mesotibia almost subequal in length. Mesotibia with one apical spur; two spines present at middle of mesotibia. Metatibia with one pair of medial spurs, one pair slightly longer than diameter of tibia, and other pair of apical spurs ca. 2 times as long as the diameter of the tibia. Metatarsi 5-segmented; two very short setae present on the apex of each tarsomere.
Etymology. The specific name is derived frpm the Latin preposition, sub (under, below), and aequalis (equal), in reference to the subequal length of the basal stems to the hind wing veins Rs 1+2 and Rs 3+4 .
Description. Mesothorax large, with prominent scutum and small scutellum; prescutum not preserved. Mesoscutum with distinct median suture, broader than long, posterior edge concave along midline; mesoscutellum fan-shaped, half the length of mesoscutum; metascutum dumbbell shaped.
Forewing moderately slender, tapering gradually to apex. Length ca. 3.1 times the width. Forewing bearing a humeral vein. Sc forked from distal 1/3 of the stem; Sc 2 extending to costal margin of wing at 3/5 length of wing from base. Crossvein sc-r present. R 1 not forked; Rs 4-branched; Rs 4 extending to the apex of forewing; Rs 1 and Rs 2 stalked, Rs 1+2 stalked ca. 0.35 of their total length; Rs 3 and Rs 4 free; Rs 1+2 furcation almost at same level as Rs 3+4 . Crossvein s present (Figs. 16C, D). M 4-branched; M 1 , after separation from M 2 subtending an angle of 75-80 degrees, sharply angulate at junction with r-m crossvein (Figs. 16C, D); stem M 1+2 longer than stem M 3+4 . CuA bifurcated; CuP simple. Three anal veins forming a double-Y configuration; 1A and 2A separate at basal half. Hind wing length ca. 2.3 times the width; broader than forewing. Sc not forked. R 1 not forked; Rs 4branched; Rs branching into veins Rs 1+2 and Rs 3+4 , and then further subdividing into four branches of Rs 1 , Rs 2 , Rs 3 , and Rs 4 ; furcations of Rs 1+2 , and Rs 3+4 almost at the same level to each other. M 4-branched. CuA bifurcated; CuP difficult to discern.
Etymology. The specific name is derived from the Latin parva (small, little, stunted), in reference to its small body size.
Locality and horizon. This specimen was collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary.
Diagnosis. The new species has narrower wings (wing index 0.31) than K. oviformis (wing index 0.33) and K. subaequalis (wing index 0.32). Crossvein m absent in forewing. Hind wing with Rs 1+2 forking almost at the same level as Rs 3+4 .
This family is defined as a clade of the Amphiesmenoptera by having a double anal furcation on the forewing and a hind wing M vein with at most three branches. This family is assigned to Lepidoptera by presence of a M 1 vein which, after separation from M 2 vein, subtends an angle greater than 60 degrees and is sharply angulate at the junction with the r-m crossvein.
Comparison. This new family with a 4-branched M is different from most other Lepidoptera, except for Agathiphagidae and Mesokristenseniidae. The differences among these three families are listed in Table 2.
Etymology. The specific name is derived from the Latin, multi (many, much), and nervis (sinew, tendon, vein), in reference to the numerous crossveins in the forewings.
Locality and horizon. Etymology. This generic name is derived from the Greek pegos (strong, solid), in reference to the large body of this species, and lepidos, for ''scale'' or ''flake,'' also referring to this species' assignment to the Lepidoptera; and pteron, for ''wing'' or ''fin.'' The gender is feminine.
Distribution. Inner Mongolia Autonomous Region, China. Diagnosis. Body relatively large. Forewing with Sc forked, R 1 forked. Crossvein r absent, r-m crossvein weak. Stem M 1+2 longer than stem M 3+4 ; m 3+4 -cua crossvein originating near M furcation and terminating at midpoint of CuA. Crossvein cua-cup located at the base of forewing. The distal part of 2A normal, not curved upward. Hind wing R 1 forked.
Comparison. Pegolepidopteron differs from Ascololepidopterix in the following characters: 1), the forewing Sc is forked (vs. Sc not forked); 2), the r crossvein is present (vs. the r crossvein absent); 3), the m crossveins are absent (vs. the m crossveins present); 4), 2A is rectilinear (vs. the distal part of 2A curved upward); and 5), the hind wing R 1 is forked (vs. R 1 not forked and curved). When compared to Agathiphaga of the monogeneric Agathiphagidae, Pegolepidopteron can be separated by the following characters: 1), the R 1 is forked (vs. the R 1 not forked); 2), the sc-r crossvein is absent (vs. the sc-r crossvein present); 3), the r crossvein is present (vs. the r crossvein absent); 4), the location of the m 3+4 -cua crossvein and the cup-a crossvein; and 5), the hind wing venation of Pegolepidopteron is much different from that of Agathiphaga.
Etymology. The specific name is derived from the Latin of latus (broad, wide), and ala, (a bird's wing), in reference to the broad wings of this species.
Locality and horizon. This specimen was collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary.
Diagnosis. Same as generic diagnosis. Description. Antennae filiform; scape swollen; flagellum filiform; length of segments equal to their diameter. Short setae on anterior head margin. Mesothorax with small prescutum; mesoscutum broader than long; anterior and posterior edges of mesoscutum concave along midline; mesoscutellum fan-shaped, relatively large; mesoscutellum almost subequal to mesoscutum in length. Mesothorax slightly longer than metathorax; metascutum dumbbell shaped. Two short spines present on the apex of each tarsomere. Family Incertae sedis Gen. et sp. incertae sedis (Fig. 21) Material. CNU-LEP-NN-2012-013; =; antennae and forelegs well preserved; venation on both fore-and hind wings difficult to discern.
Locality and horizon. This specimen was collected from Daohugou Village, Shantou Township, Ningcheng County, Inner Mongolia Autonomous Region, China. The age is latest Middle Jurassic, near the Callovian-Oxfordian boundary.
Description. Antennae longer than half the length of forewing; scape swollen; pedicel relatively robust; flagellum filiform, length of flagellar segments equal to their diameter. Maxillary palpus long, the last segment short. Foretibia with epiphysis and spines (Fig. 21C); pretarsi 5-segmented. Both mesotibia and metatibia with one pair of apical spurs; medial spurs not discernible.
Forewings extremely long, distinctly exceeding end of the abdomen. Sc forked; other wing venation not discernible.
Remarks. The tibial epiphysis is well preserved on this specimen. The foretibia is characterized by well-developed epiphyses, an autapomorphy of the Lepidoptera. Based on this character, we consider this specimen is assigned to the Lepidoptera. However, due to indistinct venational characters, it cannot be placed in any lepidopteran family.

Lepidopteran Characters from the Daohugou Specimens
Amphiesmenopteran fossils can be recognized by either the anal veins in the forewing forming a ''double-Y'' loop or by the hind wing M veins with at most three branches. Amphiesmenopteran specimens from the Middle Jurassic Jiulongshan Formation at Daohugou show that they had already acquired at least some lepidopteran or trichopteran apomorphies. Definitive Trichoptera and Lepidoptera from Daohugou previously have been reported by Gao et al. [43] and Huang et al. [25]. Daohugou Lepidoptera described here reveal an earlier underestimated diversity of Lepidoptera from this deposit. These specimens possess some of the most recently proposed lepidopteran autapomorphies.
Although Kristensen listed 23 autapomorphies for adult Lepidoptera [44], few of these can be observed on compression fossils. Grimaldi [8] specified three critical, external apomorphies that should be present in adults of early lepidopteran fossils: 1), absence of a forewing M 4 vein; 2), presence of an epiphysis on the foretibia of (most) species; and 3), the occurrence of wing scales on both fore-and hind wings. In addition, the presence of mandibulate mouthparts [12,40,45], a well-developed jugum and associated setae [40], and a frenulum [12,45] also are present and often used as diagnostic characters of basal moths [41].
One feature mentioned above, wing scales, have long been regarded as a diagnostic character for the Lepidoptera. Although a few trichopteran species also possess wing scales, they are always from rather derived lineages [46]. Grimaldi [8] mentioned that, differing from the Lepidoptera, the Trichoptera have wing scales that very occasionally occur on the forewings. However, some rare Trichoptera, such as Monocentra lepidoptera Rambur, do have wing scales on both wings [47,48]. In primitive Lepidoptera, the scales are typically ''solid'', lacking a lumen; wing-surface scales are nonperforate; and the outer surface of wing scales are densely set with transverse flutes [49]. Interestingly, only one lepidopteran fossil (CNU-LEP-NN-2012-024) from Daohugou exhibits evidence of scales, as robust piliform scales. Huang et al. [25] indicated the presence of wing scales from the Mesokristenseniidae, but their interpretation of the wing scales appears ambiguous. We believe that the absence of wing scales from Daohugou Lepidoptera is due to taphonomic factors. While scales are often preserved in amber ( [11,12], and other examples), scales are known but seldom preserved in compression fossils. Another possible explanation involves the unlikely secondary loss of wing scales from Daohugou Lepidoptera. Such an explanation, however, would require an unparsimonious assumption that these lepidopterans represent a monophyletic lineage. The morphological diversity displayed in these specimens appears to undermine such an interpretation.
Based on our survey of the literature, we consider that the following four amphiesmenopteran apomorphies [15,25] are sufficient for identifying specimens in this report as Amphiesmenoptera (Table 3).
exceptions, most of the specimens with 3-branched M veins (Figs. 1C, D, E and 2A) are most likely Lepidoptera. 12. Separation of the M 1 from the M 2 veins is accompanied by an angle greater than 60 degrees and a sharp, angulate intersection at the junction with the r-m crossvein ( Fig. 2A). Huang et al. [25] proposed that Lepidoptera can be distinguished from Trichoptera by this character of the M 1 vein. In Lepidoptera, the M 1 usually separates from M 2 at an angle greater than 60 degrees, followed by sharp angulation at junction with the r-m crossvein (Figs. 1C, F, and 2A). By contrast, nearly all Trichoptera have branches of the M 1+2 with the M 1 and M 2 veins at an angle of less than 45 degrees; in addition, and M 1 is linear and smooth (Figs. 1G and 2B). Not all Lepidoptera have a M 1 vein that is sharply angulated at the junction with r-m crossvein, such as Undopterix sukatshevae that was identified as a lepidopteran based on the presence of scales (Fig. 1D), and Netoxena nana based on its 3-branched M vein (Fig. 1E). If a fossil species has this feature, it is most likely a lepidopteran. Most of our twenty specimens exhibit wings with this character, except for two lacking this feature and three that have it as an ambiguous presence (as shown in Table 3). 13. The male valva is primarily undivided. 14. The cerci are absent in both sexes.

The Early Evolution of the Amphiesmenoptera
The Amphiesmenoptera likely originated from the stem panorpoid stock [15]. Although no fossils unambiguously represent the common ancestry of Lepidoptera and Trichoptera, the extinct family Necrotauliidae has been suggested as the best candidate ( Fig. 1A) [5]. This family is a paraphyletic assemblage of species that existed from the Triassic to the Cretaceous [50]. The earliest fossil member of the Lepidoptera, Archaeolepis mane (Fig. 1B), was reported from Sinemurian Stage, of the mid Early Jurassic age, an assignment based primarily on distinctive lepidopteran scales [18]. Characters of the wing venation, legs and axial part of the body of the various new species in this report indicate the presence of autapomorphies in both the Amphiesmenoptera and the Lepidoptera. These features provide supplemental evidence to support the hypothesized divergence of the Lepidoptera and Trichoptera occurring by the Early Jurassic. This differentiation of the Lepidoptera and Trichoptera likely had transpired during the Triassic-Jurassic boundary [50], or possibly Late Triassic [6,51]. Notably, gracile, lepidopteran-like, epidermal leaf mines reminiscent of the Nepticulidae and more basal monotrysian leaf mining lineages are present in a Late Triassic (Carnian) flora from South Africa (C Labandeira, R Prevec, E Currano, J Anderson and H Anderson, unpublished data), perhaps indicating an earlier, Middle Triassic date for the origin of basalmost lepidopteran lineages.