New fossil genus and species of Sinoalidae (Hemiptera: Cercopoidea) from the Middle to Upper Jurassic deposits in northeastern China

A new fossil genus and species of Sinoalidae, Stictocercopis wuhuaensis gen. et sp. n., from the Middle to Upper Jurassic Haifanggou Formation at Daohugou, Inner Mongolia, northeastern China is described, illustrated and its systematic position discussed, on the basis of four complete well-preserved specimens. The new genus distinctly differs from other sinoalids in having relatively complex wing venation and tegmen spots. The intra-specifi c variation in venation is also discussed. The new discovery increases the palaeodiversity of sinoalids in the early assemblage of the Yanliao biota from the Daohugou beds. ZooBank Article LSID: 7F2553EE-E341-43F9-BBB0-526FD518B9AE * Corresponding author; e-mail: dyhuang@nigpas.ac.cn INTRODUCTION The hemipteran superfamily Cercopoidea Leach, 1815 is the second largest superfamily in the Cicadomorpha, comprising approximately 3000 described species (Hamilton, 2001; Dietrich, 2002). It differs from other extant superfamilies’ of Cicadomorpha in having conical and short hind coxa, c ylindrical hind tibia with one or more large spines and a body clothed in fi ne setae (Szwedo et al., 2004; Dietrich, 2005). Adult cercopoids are commonly called froghoppers because they look like tiny frogs and are well adept at jumping (Burrows, 2003). Cercopoidea i s a relatively poorly-known group of Cicadomorpha with little knowledge on its origin, evolution, palaeoecology and palaeogeography (Cryan & Svenson, 2010; Wang et al., 2012). The fossil C ercopoids comprise nearly 40 species attributed to three extinct families (Procercopidae, Sinoalidae and Cercopionidae) known from the Mesozoic to Cenozoic and one extant family (Clastopteridae) from Dominican amber (Poinar et al., 2014; Chen et al., 2015). Cercopoidea was one of the superfamilies derived from the Triassic family Hylicelloidea (Shcherbakov, 1992, 1996). The earliest Cercopoidea are represented by Procercopidae, recorded from the Lower Jurassic in Germany (Handlirsch, 1906). Other Procercopidae are known from the Early Jurassic to Early Cretaceous in Germany, Eur. J. Entomol. 115: 127–133, 2018 doi: 10.14411/eje.2018.011


INTRODUCTION
The hemipteran superfamily Cercopoidea Leach, 1815 is the second largest superfamily in the Cicadomorpha, comprising approximately 3000 described species (Hamilton, 2001;Dietrich, 2002).It differs from other extant superfamilies' of Cicadomorpha in having conical and short hind coxa, c ylindrical hind tibia with one or more large spines and a body clothed in fi ne setae (Szwedo et al., 2004;Dietrich, 2005).Adult cercopoids are commonly called froghoppers because they look like tiny frogs and are well adept at jumping (Burrows, 2003).
Cercopoidea i s a relatively poorly-known group of Cicadomorpha with little knowledge on its origin, evolution, palaeoecology and palaeogeography (Cryan & Svenson, 2010;Wang et al., 2012).The fossil C ercopoids comprise nearly 40 species attributed to three extinct families (Procercopidae, Sinoalidae and Cercopionidae) known from the Mesozoic to Cenozoic and one extant family (Clastopteridae) from Dominican amber (Poinar et al., 2014;Chen et al., 2015).Cercopoidea was one of the superfamilies derived from the Triassic family Hylicelloidea (Shcherbakov, 1992(Shcherbakov, , 1996)).The earliest Cercopoidea are represented by Procercopidae, recorded from the Lower Jurassic in Germany (Handlirsch, 1906).Other Procercopidae are known from the Early Jurassic to Early Cretaceous in Germany, Stictocercopis wuhuaensis sp.n.
Material.Holotype, NIGP166867 (a, b), a well-preserved adult male in dorsal-ventral aspect with fore and hind wings extended.Paratype includes three males, NIGP166868, NIGP166869 and NIGP167803, nearly complete in dorsal-ventral aspect with fore and hind wings extended.Diagnosis.As for genus (vide supra).Description.Total length 12.7 mm in holotype (NIGP166867), 12.4 mm in NIGP166868, 12.5 mm in NIGP166869 and NIGP167803; tegmen 10.2 mm long and 3.2 mm wide in the holotype (NIGP166867), 9.8 mm long and 3.1 mm wide in NIGP166868, 9.8 mm long and 3.0 mm wide in NIGP167803, and tegmen deformed in NIGP166869.The following measurements are based on the holotype.
Head not fl attened, rounded apically (Figs 1D, 2B); compound eyes large, located laterally, nearly globo se; postclypeus swollen, with transverse impressions, 0.95 mm long and 0.44 mm wide, in facial portion with median concavity extending slightly towards the crown; anteclypeus less swollen, nearly half the length of postclypeus, and clypellus is triangularly elongated; three ocelli present, ocellar triangle distinct (Fig. 2B); loral plates wider than maxillary plate, crescent-like in ventral view, 1.0 mm long and 0.3 mm wide; maxillary plate subquadrate in cross-section; antennae setiform, inserted in deep cavities between the eyes, about 1.3 mm long, fl agellum with at least eight elongate segments; scape large but short, pedicel thinner and longer than scape, fl agellomeres 1 to 8 becoming gradually thinner and shorter (Figs 1E, F); rostrum 2.3 mm long, reaches base of hind coxae.
Tegmen dotted with elliptical spots on veins, with length/ width ratio about 3.1 (Figs 1G, 2G), punct ate (less punctate near apex), appendix very narrow, costal margin thickened, slightly arched at base; posterior margin straight; apical margin rounded; basal cell about 0.24 times as long as tegmen; branch ScP + RA nearly 1.8 times longer than stem ScP + R; ScP + R branching into ScP + RA and RP at 0.47 length from base of tegmen; stem ScP + RA branching into ScP and RA after vein MP branching at 0.72 length from base of tegmen; RA with 3-4 branches, connected with RP by cross vein ir at 0.83 length measured from base of tegmen; RP with 2 branches, connected with MP 1+2 by r-m at 0.77 tegmen length; MP branching into MP 1+2 and MP 3+4 d istinctly basal of CuA branching at 0.64 tegmen length, Herein we describe a new fossil genus and species of Sinoalidae, Stictocercopis wuhuaensis gen.et sp.n. from the Middle to Upper Jurassic Haifanggou Formation at Daohugou, Inner Mongolia, northeastern China.

MATERIAL AND METHODS
The new species is erected on the basis of four specimens, two of which are complete with parts and counterparts, and the two remaining specimens are nearly complete without counterparts.All these specimens are dorso-ventrally compressed and display fi ne details including antennae, ocelli, ornaments on tegmen, hind wings, legs and terminals.They were collected at Xiayingzi, the deposits at which occur below layers with Conchostraca in the Daohugou beds (for the map of fossil layers that yielded new species and locations near Daohugou, see Jiang et al., 2016).They are preserved in grey or dark greyish fi ne laminated tuffaceous shale.All these fossils come from the Daohugou beds in the Haifanggou Formation with a geological age close to the Middle to Upper Jurassic boundary (163.5 Ma) (Huang, 2016).
All specimens were carefully prepared using a sharp knife, and studied under a Leica MZ16A dissecting microscope.Line drawings were prepared using a binocular Olympus SZX7 microscope and a camera lucida.Photographs were taken using a digital camera attached to a Zeiss Discovery V20 microscope, and some were moistened with 70% ethanol to show fi ne details.Photomicrographs of general habitus were taken using a Canon EOS 5D Mark II camera with a Canon 100 mm macro lens.Micro surface information was obtained under the Low Vacuum mode (100 Pa in sample chamber) of a Hitachi SU-3500 SEM with the accelerating voltage set at 20.0 KV.The material studied here is deposited at the Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, China.
Th e venation terminologies used herein follow the interpretations of wing venation for all Paraneoptera (Nel et al., 2012) with slight modifi cations and r eference to the standardized terminology of the forewing venation in Fulgoromorpha (Bourgoin et al., 2015).Etymology.The generic name is a combination of the Greek word "stiktos" (στικτός) = spotted, which indicates the spotted tegmen and the known genus Cercopis.Gender: masculine.

Diagnosis.
The new genus distinctly differs from other known genera in the following characters: a ntenna setiform, fl agellum bearing at least eight elongate segments; tegmen dotted with elliptical spots on veins; RA with 3-4 branches; RP with 2 branches; MP with 5 terminals; hind wings, MP with 2 branches, branching at the same level of CuA; hind tibia armed with two rows of a total of 5-7 large lateral spines.with 5 terminals, slightly contorted near tegmen apex; stem MP 1+2 branching into MP 1 and MP 2 at the same level of r-m; im slant, connecting MP 2 and MP 3 or connecting MP 2 and M 3+4 at the dividing point; MP 4 bifurcating MP 4a and MP 4b halfway; C3 developed, with length/width ratio about 3.5; CuA curved anteriorly, bifurcating into branch-   es CuA 1 and CuA 2 distinctly after MP branching; branch CuA 1 about 1.7 times longer than CuA 2 ; m-cu after CuA branching and connected with CuA 1 ; CuP almost straigh t; PCu slightly distorted; A 1 sinuous.Hind wings partly visible, subtriangular, distinctly shorter than tegmen, without peripheral membrane; MP with 2 branches, branching into MP 1+2 and MP 3+4 at same level as CuA branches; CuA with 2 branches; cross vein r-m at the same level of m-cu.
Fore fe mur robust, approximately 1.2 mm long and 0.5 mm wide; fore ti bia circa 1.5 times longer than femur; fore tarsus with three tarsomeres (Fig. 2D), circa 0.9 mm long, tarsal claws distinct; middle femur approximately 1.3 mm long, and more slender than fore femur; middle tibia longer than fore tibia; hind coxae enlarged and transverse, circa 1.4 mm long and 0.9 mm wide; hind trochanter about 0.7 mm long; hind femur circa 1.6 mm long and 0.4 mm wide; hind tibia 3.5 mm long, nearly twice as long as fore tibia, with two rows of large lateral spines (Fig. 1H), one row with 3-4 spines and the other with 2-3 spines, hind tibia slightly widened apically, armed wit h two rows of at least 9 apical tiny teeth with subapical setae; hind tarsus nearly tw ice as long as fore tarsus, with three tarsomeres (Fig. 2F); basal tarsomere as long as third tarsomere and longer than second tarsomere, armed with a row of apical teeth; apex of second tarsomere armed with at least 14 apical teeth; tarsal claws short and robust, sharp apically; arolium present.

DISCUSSION
The new g enus can be attributed to Sinoalida e based on the following apomorphic characters: tegmen partly punctate, costal margin thickened, almost extending to apex of tegmen; MP branching into M 1+2 and M 3+4 distinctly basad of bifurcation of CuA; cross vein im and m-cu present; hind wing s without peripheral membrane; hind tibia with two rows of a total of 5-7 lateral spines.
The new genus distinctly differs from the other known genera in the presence of tegminal spots and a relatively complex wing venation on both tegmen and hind wings as follows.
(1) RA with 3-4 branches, RP with 2 branches, and MP branching with 5 terminals in new genus in contrast to RA and RP with single branch, MP with two terminals in other genera.(2) MP of hind wings with 2 branches in new genus in contrast to a single branch in other genera.
(3) The cross vein r-m in hind wings at the same level as m-cu in new genus in contrast to m-cu earlier than r-m in Heibeicercopis and Sinoala.(4) Antennal fl agellum has eight segments in the new genera in contrast to at least six segments visible in Sinoala.
The tegmina l venation of Stictocercopis wuhuaensis is variable.For example, RA with 3 branches in the holotype (NIGP166867) and paratype (NIGP166868), but with 4 branches in another paratype (NIGP166869); cross vein r-m basal of m-cu in NIGP166868, but distal of m-cu in NIGP166867 and NIGP166869; cross vein im connects MP 2 and MP 3 in NIGP166867 and NIGP166868, but connects M 2 and the dividing point of M 3+4 in NIGP166869.These specimens were collected in the same horizon and locality, of similar size, length/width ratio of tegmen and body structures, and the variation is limited to terminal branches and connecting position of cross veins.Therefore, these specimens could be attributed to the same species.
To date, the Sinoalidae includes seven genera only from the Middle to Upper Jurassic in northeastern China.The new species provides new insights into the biodiversity of Mesozoic Sinoalidae and increases our understanding of the origin and evolution of the family.

Fig. 1 .
Fig. 1.Male holotype of Stictocercopis wuhuaensis gen.et sp.n. from the Middle to Upper Jurassic Haifanggou Formation at Daohuguo.A -counterpart (NIGP166867b), general habitus with dorsal structures; B -part (NIGP166867a), general habitus with ventral structures; C -enlargements of A, showing the details of genitals; D -showing the details of head and pronotum; E and F -enlargements of A, showing the details of left antenna with nine elongate segments; G -showing the details of right tegmen; H -enlargements of B, showing the details of hind tibia.A-C, E, F, H moistened with 70% ethanol.Scale bars: 2 mm (A, B, G); 1 mm (C-F, H).

Fig. 2 .
Fig. 2. Paratypes, males of Stictocercopis wuhuaensis gen.et sp.n., from the Middle to Upper Jurassic at Daohuguo.A -NIGP166868, general habitus in ventral view; B -enlargement of A, showing the details of head structure with three ocelli (white arrows); C -enlargement of A, showing the details of genitals; D -enlargement of A, showing the details of fore tarsi and claws; E -NIGP166869, general habitus in ventral view; F -enlargement of E, showing the details of hind tarsi; G -enlargement of E, showing the details of right tegmen (deformed).A -F moistened with 70% ethanol.Scale bars: 2 mm (A, E, G); 1 mm (B, C); 0.5 mm (D, F).

ACKNOWLEDGEMENTS.
This work was funded by the Ministry of Science and Technology (2016YFC0600406), the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB18000000 and XDPB05), and the National Natural Science