Introduction
The mid-Mesozoic Eolepidopterigina is an extinct suborder of moths within the Lepidoptera. A single family, the Eolepidopterigidae, constitutes this suborder. The Eolepidopterigidae is inferred to have fed on pollen and to have laid eggs as elongate lesions in plant substrates (Rasnitsyn, Reference Rasnitsyn1983). Within the Eolepidopterigina, another closely related lineage, the Undopterigidae, was erected to accommodate the genus Undopterix Skalski, Reference Skalski1979. However, subsequent examination of these specimens showed that the long apophyses in the female genitalia and the wing venation of Undopterix are similar to those present in the Eolepidopterigidae. Consequently, the Undopterigidae is considered a junior synonym of the Eolepidopterigidae (Rasnitsyn, Reference Rasnitsyn1983; Skalski, Reference Skalski1990; Sohn et al., Reference Sohn, Labandeira, Davis and Mitter2012; Zhang et al., Reference Zhang, Shih, Labandeira, Sohn, Davis, Santiago-Blay, Flint and Ren2013).
To date, 15 fossil species of Eolepidopterigidae have been reported worldwide. The type genus Eolepidopterix is represented by Eolepidopterix jurassica Rasnitsyn, Reference Rasnitsyn1983, restricted to the Upper Jurassic of Transbaikalia, Russia. Seven species described from the latest Middle Jurassic of China currently are the oldest known eolepidopterigid records (Zhang et al., Reference Zhang, Shih, Labandeira, Sohn, Davis, Santiago-Blay, Flint and Ren2013). In addition to Eolepidopterix, the following eolepidopterigids have been reported: Palaeolepidopterix aurea Kozlov Reference Kozlov1989, from the Late Jurassic deposits of Kazakhstan; Daiopterix rasnitsyni Skalski Reference Skalski1984 and D. olgae Kozlov Reference Kozlov1989, from the Upper Jurassic deposits of Russia (Skalski, Reference Skalski1984; Kozlov, Reference Kozlov1989); and Netoxena nana (Martins-Neto, Reference Martins-Neto1999), Undopterix caririensis Martins-Neto and Vulcano Reference Martins-Neto and Vulcano1989 and Gracileopterix pulchra Martins-Neto and Vulcano Reference Martins-Neto and Vulcano1989, from the late Early Cretaceous of Brazil (Martins-Neto and Vulcano, Reference Martins-Neto and Vulcano1989). Additionally, Undopterix sukatshevae Skalski Reference Skalski1979, placed originally in Micropterigidae, was formally transferred to Eolepidopterigidae (Skalski, Reference Skalski1979, Reference Skalski1990; Kozlov, Reference Kozlov1988).
Recently, we collected well-preserved fossil moths from the Jiulongshan Formation near Daohugou Village, Ningcheng County of Inner Mongolia, in northeastern China. The geological age of the Daohugou fossil-bearing beds formerly was considered as mid Middle Jurassic, based on a radioisotopic date of 165 Ma (Ren et al., Reference Ren, Gao, Guo, Ji, Tan and Song2002; Gao and Ren, Reference Gao and Ren2006). Because of new calibrations established for the Jurassic System (Walker et al., Reference Walker, Geissman, Bowring and Babcock2013), this site now should be considered as latest Middle Jurassic, corresponding to a late Callovian Age. The Jiulongshan Formation is considered part of the Yanliao Biota, yielding a Lagerstätte of excellently preserved plants, insects, dinosaurs, pterosaurs, birds, and mammals (Ji et al., Reference Ji, Luo, Yuan and Tabrum2006; Ren et al., Reference Ren, Shih, Gao, Yao and Zhao2010; Gao et al., Reference Gao, Shih, Xu, Wang and Ren2012; Gu et al., Reference Gu, Montealegre-Z, Robert, Engel, Qiao and Ren2012; Yang et al., Reference Yang, Makarkin, Winterton, Khramov and Ren2012). From this deposit, a new genus and species, Aclemus patulus n. gen. n. sp., assigned to the Eolepidopterigidae, is described herein. In addition, the diagnosis of Longcapitalis excelsus Zhang, Shih, Labandeira and Ren 2013, is emended based on additional new material.
Material and methods
This study is based on two specimens housed at the fossil insect collection of the Key Lab of Insect Evolution and Environmental Changes at the College of Life Sciences, Capital Normal University (CNU), in Beijing, China. Camera Lucida drawings were prepared with the aid of drawing tube attached to a Leica MZ12.5 stereomicroscope. The drawings were imported into a computer by an Epson 5100 scanner, and color- and contrast-balanced with Adobe Photoshop CS2 graphics software. Photographs were acquired by a Nikon DXM1200C Digital Camera.
We follow the wing venation nomenclature of Wootton (Reference Wootton1979). The relevant abbreviations are: C, costa; Sc, subcosta; R, radius; R1a and R1b, anterior and posterior branches of the anterior radius, respectively; Rs, posterior branch of R (composed of the Rs1, Rs2, Rs3, and Rs4); M, media; M1+2, anterior branch of the M, with M1 and M2 fused; M3+4, posterior branch of the M, with the M3 and M4 fused; Cu, cubitus; CuA, anterior branch of the cubitus (composed of the CuA1 and CuA2); CuP, posterior branch of the cubitus; and 1A, 2A, and 3A, the first, second, and third branches of the anal vein.
The body length was measured along the midline from the anterior margin of the frons to the apex of the abdomen, minus appendicular structures. The width was measured across the broadest part of the body along the sagittal axis, at the thorax. The wing length was measured from the basal zone of articulatory sclerites to the apex of the wing. The wing index is defined as the ratio of wing width/wing length. All measurements are given in millimeters.
Systematic paleontology
Order Lepidoptera Linné, 1758
Suborder Eolepidopterigina Rasnitsyn, Reference Rasnitsyn1983
Family Eolepidopterigidae Rasnitsyn, Reference Rasnitsyn1983
Genus Aclemus new genus
Type species
Aclemus patulus n. sp., by monotypy.
Diagnosis
As for the type species by monotypy (see below).
Etymology
The generic name, Aclemus, is a combination of the Greek A-, meaning “lack of” or “absence”, and the Latin–clemus, meaning “twig” or “branch,” which refers to both the Sc and R1 veins lacking a bifurcation. The sex is masculine.
Occurrence
Daohugou locality, Inner Mongolia Autonomous Region, in northeastern China.
Aclemus patulus new species
Figure 1 Camera lucida drawing of the forewings. (1) Aclemus patulus n. gen. n. sp. (2) Eolepidopterix jurassica Rasnitsyn, Reference Rasnitsyn1983 (modified from Rasnitsyn, Reference Rasnitsyn1983). (3) Grammikolepidopteron extensus Zhang, Shih, Labandeira and Ren, 2013 (modified from Zhang et al., Reference Zhang, Shih, Labandeira, Sohn, Davis, Santiago-Blay, Flint and Ren2013). (4) Daiopterix rasnitsyni Skalski, Reference Skalski1984 (modified from Skalski, Reference Skalski1984). (5) Longcapitalis excelsus Zhang, Shih, Labandeira and Ren, 2013 (modified from Zhang et al., Reference Zhang, Shih, Labandeira, Sohn, Davis, Santiago-Blay, Flint and Ren2013).
Figure 2 (1) Camera lucida drawing of Aclemus patulus n. gen. n. sp., holotype, ♂, CNU-LEP-NN-2013-001. (2–4) Photographs of Aclemus patulus n. gen. n. sp., holotype, ♂, CNU-LEP-NN-2013-001. (2) General habitus. (3) Forewing. (4) Hindleg. co, coxa; fe, femur; sp, spur; tr, trochanter. Arrowhead indicates terminal spinules for each tarsomere.
Type
Holotype; male; specimen CNU-LEP-NN-2013-001; hindleg, abdomen, and wings clearly visible, but basal and anal area of fore- and hindwings poorly preserved.
Diagnosis
The new fossil species can be identified by the following combination of characters: all legs with setae; metatibia with one pair of medial spurs and one pair of apical spurs; forewings and hindwings lacking cilia on their anterior margins; forewing veins Sc and R1 unforked, cross-veins r-m and m3-cua1 present; hindwing veins, Sc and R1 unforked, cross-vein m3-cua1 present.
Aclemus n. gen. (Fig. 1.1) is differentiated from the type genus of Eolepidopterigidae, Eolepidopterix Rasnitsyn, Reference Rasnitsyn1983 (Fig. 1.2), in having the forewing with Sc and R1 unforked (vs. forewing with Sc and R1 bifurcated). The Sc unforked condition is a derived character. Aclemus shares this character with Palaeolepidopterix, Netoxena, Gracileopterix, and Grammikolepidopteron. R1 unforked also is considered a derived character. Aclemus shares this character with Netoxena, Grammikolepidopteron, and Longcapitalis.
The venation of Aclemus resembles that of Grammikolepidopteron Zhang et al., Reference Zhang, Shih, Labandeira, Sohn, Davis, Santiago-Blay, Flint and Ren2013 (Fig. 1.3), but Aclemus differs from the latter by the R vein bifurcated into R1 and Rs veins, which further subdivide into the veins Rs1+2 and Rs3+4 and then into the 4 branches of Rs1, Rs2, Rs3 and Rs4, deployed in successively stepped branching points (vs. branching points of R1 and Rs1 to Rs3 that are linearly aligned). In the primitive moths, Rs veins usually present as in Aclemus. Thus the former arrangement of Rs veins is inferred to be the primitive state. In Eolepidopterigidae, only Netoxena nana and Grammikolepidopteron extensus possess the derived state.
Aclemus resembles Longcapitalis Zhang et al., Reference Zhang, Shih, Labandeira, Sohn, Davis, Santiago-Blay, Flint and Ren2013 (Fig. 1.5), but it differs from the latter by the following: (1) the forewing with the Sc is unforked (vs. forewing with the Sc bifurcated); (2) the presence of an m3-cua1 cross-vein in both the forewing and hindwing (vs. m3-cua1 crossvein absent)—the presence of a cross-vein between M and CuA is probably the homoplasious condition, which Aclemus shares with Daiopterix rasnitsyni; and (3) all legs bear setae (vs. legs lacking setae). The presence or absence of leg setae is highly variable within the family and the genus. Consequently, this character is viewed as a homoplasy. Setae occur in a number of Eolepidopterigidae, such as Aclemus patulus, Eolepidopterix jurassica, Daiopterix olgae, Akainalepidopteron elachipteron, and Dynamilepidopteron aspinosus, but are lost in the other species.
Aclemus shows similarity to the genus Daiopterix Skalski, Reference Skalski1984 (Fig. 1.4), but it differs from the latter in the following characters: (1) the forewing has the Sc and R1 unforked (vs. forewing with Sc and R1 veins bifurcating), (2) the hindwing with the R1 is unforked (vs. the R1 forked), and (3) the hindleg possesses setae (vs. a hindleg without setae).
Occurrence
This specimen was collected near Daohugou Village, Shantou Township, Ningcheng County, of the Inner Mongolia Autonomous Region, in northeastern China. The fossil bed is the latest Middle Jurassic and late Callovian in age.
Description
Eyes oval, with sparse pubescence along the outer ocular margin. Mesofemora longer than mesotibiae; mesotibiae with irregularly arranged setae; mesotibial spurs difficult to identify. Hindlegs well preserved; metafemora 0.6 times as long as metatibiae; metatibiae with irregularly arranged setae, and with one pair of medial spurs and one pair of apical spurs; both pairs of spurs approximately 1–1.5 times as long as the diameter of the tibiae (Fig. 2.4); metatibiae 1.2 times as long as metatarsi. Tarsi 5-segmented, with terminal spinules at each tarsomere (Fig. 2.4, black arrows); tarsomere I longest, about 2.0 times as long as tarsomere II; tarsomeres II, III, IV subequal to each other, with tarsomere IV slightly longer than tarsomere V.
Forewing moderately broad, and with a rounded margin distally (Figs. 1.1, 2.3). Wing index of forewing ca. 0.25. Sc unforked, extending to the costal margin at two-thirds length of the wing from its base. R1 unforked; Rs 4-branched; Rs4 extending to apex of forewing; Rs1+2 and Rs3+4 furcations arising at about the same level. M 3-branched. CuA bifurcated; CuA furcation beyond M furcation. Cross-vein m3-cua1 present, originating at 1/3 length of M3 from M2+3 furcation and terminating at one-third length of CuA1 from CuA furcation. CuP and anal veins not preserved. Hindwing venation resembling forewing. Sc and R1 unforked; Rs 4-branched, Rs1+2 and Rs3+4 furcations arising at the same level; M 3-branched; CuA bifurcated; cross-vein m3-cua1 present. Measurements: body length ca. 5.2, width 1.3; forewing length 4.8, width 1.8.
Etymology
The specific name is derived from the Latin, patulus (unfolding), referring to the unfolded posture of the insect body.
Remarks
An affiliation to the Lepidoptera is supported by the absence of the M4 vein on the forewing, and an Ml vein with a markedly angulate position at the junction with cross-vein r-m, which is a previously unrecognized autapomorphy of the Lepidoptera (Huang et al., 2010).
This genus is assigned to the family Eolepidopterigidae by a combination of the following four features: (1) the fore- and hindwings are homonomous, (2) the M vein is three-branched, (3) the wings lack long cilia on their margin, and (4) a cross-vein is absent between the Sc and R veins.
Longcapitalis Zhang, Shih, Labandeira and Ren, 2013
Type species
Longcapitalis excelsus Zhang, Shih, Labandeira and Ren, 2013; by monotypy.
Diagnosis
As for the type species, by monotypy (see below).
Occurrence
Daohugou locality, Inner Mongolia Autonomous Region, northeastern China.
Longcapitalis excelsus Zhang, Shih, Labandeira and Ren, 2013
Figure 3 (1) Camera lucida drawing of Longcapitalis excelsus Zhang, Shih, Labandeira and Ren 2013, ♂, CNU-LEP-NN-2013-004P/C, new material. (2–5) Photographic images of Longcapitalis excelsus Zhang, Shih, Labandeira and Ren 2013, ♂, CNU-LEP-NN-2013-004P/C. (2) General habitus, counterpart. (3) General habitus, part. (4) Forewing. (5) Foreleg, mid leg and antennal articles. ant, antenna; co, coxa; fe, femur; ti, tibia; tr, trochanter; I–V, tarsomeres I–V. Arrowhead indicates boundaries between tarsomeres.
2013 Longcapitalis excelsus Zhang, Shih, Labandeira, and Ren, p. 16, fig. 11
Holotype
CNU-LEP-NN-2012-025P/C (part and counterpart).
Diagnosis
The diagnostic characters of the legs are added. (1) Mesotibiae have two pairs of spurs. (This feature excludes this taxon from Eolepidopterix, Seresilepidopteron and Quadruplecivena.) (2) The absence of setae on all tibiae. (This feature excludes this taxon from Eolepidopterix jurassica and Daiopterix olgae.)
Occurrence
This specimen was collected from the same locality where the holotype was collected.
Description
Characters of the antennae and legs are added, based on the new specimen, as follows. Antenna with scape swollen, scape and pedicel broader than flagellomeres, flagellum filiform, length of segments less than their diameters, total length of antenna subequal to half the length of the forewing. Last segments of labial palpi visible, protruding from head underside. Forefemora subequal to foretibiae; foretibiae 0.6 times as long as foretarsi; foretarsi 5-segmented, tarsomere I longest. Mesofemora longer than forefemora, slightly shorter than mesotibiae; mesotibiae with one pair of medial spurs and one pair of apical spurs; mesotibiae 0.6 times as long as mesotarsi. Mesotarsi 5-segmented (Fig. 3.5); tarsomere I as long as the total length of the rest segments; tarsomere II subequal to tarsomere III; slightly longer than tarsomere IV; tarsomere IV subequal to tarsomere V. Hindleg very long, about 1.5 times as long as mid leg. All legs lacking setae. Characters on thorax and wings are the same as the holotype specimen. Measurements (new material): body length 10.5 and width 2.5, forewing length 11.8 and width 4.2.
Material
Male, specimen CNU-LEP-NN-2013-004P/C (part and counterpart); well-preserved left forewing and legs, parts of head and left hindwing.
Remarks
The diagnosis of the genus is emended, based on the new fossil specimen that has good preservation of the fore-, mid- and hindlegs. Our comparison of this new specimen to the holotype revealed that Zhang et al. (Reference Zhang, Shih, Labandeira, Sohn, Davis, Santiago-Blay, Flint and Ren2013) confused the midlegs with the hindlegs.
Discussion
The Eolepidopterigidae, proposed by Rasnitsyn in 1983, was based on only one specimen of Eolepidopterix jurassica with limited diagnosable characters. Subsequently, 14 genera with 16 species in this family, including the new taxon reported here, have been documented from Russia, Kazakhstan, China, and Brazil. These species collectively improve the morphological definition of the Eolepidopterigidae. The tibial spur formula is considered one of the important diagnosable elements for distinguishing basal lepidopteran families, because it is typically consistent within a family (Table 1). However, there are exceptions, such as Psychidae with tibial spurs 0-2-4, 0-1-1 or absent (Nielsen and Common, Reference Nielsen and Common1991), and Hesperiidae with tibial spurs 0-2-4 and rarely 0-2-2. Rasnitsyn (Reference Rasnitsyn1983) proposed that the mesotibiae of Eolepidopterigidae possessed two apical spurs, although the presence of preapical spurs was not excluded. Among the specimens previously reported, only Eolepidopterix jurassica, Seresilepidopteron dualis, Quadruplecivena celsa, and Longcapitalis excelsus have well-preserved mesotibiae. Two apical mesotibial spurs are visible on the first three species. The new material of Longcapitalis excelsus, bearing two medial and two apical spurs on their mesotibiae, provides a new character for the Eolepidopterigidae. Our update of the tibial spur formula of Eolepidopterigidae provides for a common presence of 0-2-4 and the rare occurrence of 0-4-4.
Table 1 Tibial spur formula of non-Glossatan families and the suborder Glossata
Acknowledgments
This research was supported by the National Basic Research Program of China (973 Program) (grant 2012CB821906), National Natural Science Foundation of China (grants 31172143, 31230065, 31272352, 41272006 and 41402009), Project of the Great Wall Scholar and KEY project of the Beijing Municipal Commission of Education (grant KZ201310028033), Natural Science Foundation of Hebei Province (grant D2015403010), China Geological Survey (grant 1212011120115), and the PhD Research Startup Foundation of Shijiazhuang University of Economics (No. BQ201319). This is contribution 264 of the Evolution of Terrestrial Ecosystems Consortium of the National Museum of Natural History, in Washington, D.C., U.S.A.
