A new mesoserphid wasp from the Middle Jurassic of northeastern China (Hymenoptera, Proctotrupoidea)

A new genus and species of Mesoserphidae (Hymenoptera), Juraserphus modicus gen. et sp. nov., is described based on a well-preserved fossil specimen from the Middle Jurassic Jiulongshan Formation of northeastern China. It is characterized by the following forewing features: the forking of Rs+M located approximately one-third of the distance between 1m-cu and 2r-rs, both 1cu-a and 2cu-a antefurcal; 1-M more than twice as long as 1m-cu and hind wing with cells r and rm closed. In addition, it has a short ovipositor, only extending slightly beyond the metasomal apex. Its new morphological characters broaden the diversity of Mesoserphidae in the Mesozoic and provide new insights into the evolution and relationships of Mesoserphidae.


Introduction
The superfamily Proctotrupoidea, a basal group of Prototrupomorpha within Apocrita, includes 11 extant families and one extinct family (Grimaldi & Engel 2005).Mesoserphidae was erected by Kozlov (1970), representing the only extinct family of Proctotrupoidea.Fossil records of mesoserphids can be traced back to the Middle Jurassic according to the earliest fossil from the upper Middle Jurassic Jiulongshan Formation of northeastern China (Shih et al. 2011).This family was once considered to comprise two subfamilies: Mesoserphinae Kozlov, 1970 andKarataoserphinae Rasnitsyn, 1994 (Grimaldi & Engel 2005).However, the latest research based on a phylogenetic analysis indicated that these two subfamilies a re paraphyletic and should be abandoned (Li et al. 2016).
So far, 22 fossil genera with 53 species have been described worldwide (including their locality, stratigraphic level, external morphological characteristics and body measurements), mostly distributed in

Material and methods
The fossil specimen studied herein was collected from the upper Middle Jurassic Jiulongshan Formation at Daohugou Village, Wuhua Town, Ningcheng City, Inner Mongolia, China and is housed in the Shandong Tianyu Museum of Nature in Pingyi County, Shandong Province, China.

Diagnosis
Forewing 1-Rs as long as 1-M; 1-M more than twice as long as 1m-cu; 2r-rs arising from middle of pterostigma, its width more than twice as long as width of pterostigma; 1cu-a antefurcal, 2cu-a antefurcal; forking of Rs+M located approximately one-third of distance bewteen 1m-cu and 2r-rs, closer to 1m-cu; cell 1mcu complete trapezoid and less than half of cua.Hind wing with cells r and rm closed.Metasoma spindle-shaped, with elongated segments.Short ovipositor, only extending slightly beyond metasomal apex.

Etymology
The generic name is composed of the prefi x 'Jura' from the Jurassic period and the suffi x of the genus name ' serphus'.The gender is masculine.

Species included
Type species only.

Etymology
The specifi c epithet is an adjective derived from the Latin word 'modicus', which means 'moderate, average', indicating that both the body and forewing lengths are medium.

Description
Body length 8.66 mm.Head transversely ovoid, length 1.31 mm and width 0.63 mm.Eye large, oviod and protruding.Antenna fi liform, thin, with nine antennomeres preserved, the fi rst fl agellomere long, subsequent fl agellomeres gradually decreasing in length from base to apex.
Mesosoma about as wide as head; pronotum trapezoid, extremely short and obviously narrower than head and about 3.6 times as wide as long (length 0.96 mm; width 0.27 mm); mesoscutum subquadrate, 0.86 mm long and 0.37 mm wide; mesoprescutum length 0.52 mm and width 0.43 mm; notauli present and reaching transverse mesonotal suture; mesoscutellum triangular; mesopostnotum rectangular, 0.5 times as wide as long; metascutellum preserved and almost as long as wide.Metasoma spindle-shaped, with seven segments, fi rst observed segment very short, subtrapezoidal; second to fi fth segments similar to fi rst in shape and length, but gradually increasing in width; sixth segment reversely trapezoidal and about twice as long as fourth segment; seventh segment about as long as sixth segment; valvifer 1, valvifer 2 and valvula 3 clearly discernible; ovipositor short, slightly stretched out of metasomal apex.
Left foreleg with only femur preserved, small.Left midleg well preserved, with femur wider than tibia; tibia slender; tarsus thin, with basitarsus longest and about twice as long as 2 nd tarsomere, 3 rd tarsomere obviously shorter than 2 nd , 4 th shorter and thinner than 3 rd , 5 th twice as long as 4 th and possessing two short claws.Left hindleg with femur narrow basally and widened apically, with a spindle-like shape; tibia thicker than midtibia; tarsi similar to midtarsi.Forewing length 7.05 mm, width 2.73 mm.Pterostigma long and slightly oblique apicad, six times as long as wide.1-Rs and 1-M equal in length; 1-M more than twice as long as 1m-cu; 2r-rs arising from middle of pterostigma, oblique, about 2.5 times as long as pterostigmal width.Cell 1+2r fi ve-sided and surrounded by R, 1-Rs, 1-Rs+M, (2-Rs+M) + (2-Rs) and 2r-rs; M+Cu straight and distinct, M and Cu straight basally, slightly curved apically; 1-Rs origin at a distance from pterostigma (about twice as long as 1-Rs), and 2r-rs arising from middle of pterostigma; forking of Rs+M located approximately onethird of distance between 1m-cu and 2r-rs; both 1cu-a and 2cu-a antefurcal; cell 1mcu subtrapezoidal, 1.8 times as long as wide basally; 1cu-a slightly longer than 1-M and two-thirds of 2cu-a in length.Hindwing with long, oblique r-m meeting Rs near its base ; cell r long and closed; M+Cu and Cu partly tubular; M tubular.

Discussion
Various morphological characters of Mesoserphidae have been recorded from the latest Middle Jurassic to Early Cretaceous (Zhang & Zhang 2000;Shih et al. 2011;Shi et al. 2013;Li et al. 2016).Compared with other mesoserphids, Juraserphus gen.nov.has the rare combination of both 1cu-a and 2cu-a being antefurcal in the forewing, and cells rm and r closed in the hindwing.Additionally, Juraserphus gen.nov. is unique among Mesoserphidae in having a female metasoma with fi ve basal terga very short and jointly occupying only half of metosoma's length, whilst the other half is formed by terga 6 and 7 only.
Juraserphus gen.nov.resembles Beipiaoserphus Zhang &Zhang, 2000 andBasiserphus Li et al., 2016 with both 1cu-a antefurcal and 2cu-a antefurcal in the forewing, but differs from them in having the forking of Rs+M located at a distance of one-third between 1m-cu and 2r-rs, and 1-M about twice as long as 1m-cu (vs one half and 1-M much shorter than 1m-cu in Beipiaoserphus; one-sixth or onequarter and 1-M slightly longer than 1m-cu in Basiserphus).Juraserphus gen.nov has long crossvein 2r-rs, which is more than twice as long as the width of the pterostigma.The length of 2r-rs, however, is less than 1.5 times the width of the pterostigma in Codoserphus Shi et al., 2013 and more than fi ve times as long as the width of the pterostigma in Turgoserphus Rasnitsyn, 1990 (Rasnitsyn 1990;Shi et al. 2013).1cu-a and 2cu-a of the forewing offer signifi cant characteristics.Juraserphus gen.nov has both 1cu-a and 2cu-a antefurcal, as in Campturoserphus Rasnitsyn, 1986, Scoliuroserphus Rasnitsyn, 1986and Basiserphus Li et al., 2016, but is different from the latter two and from Lordoserphus Rasnitsyn, 1994 andSinoserphus Shih et al., 2011 in the 1cu-a and 2cu-a being interstitial, from Apiciserphus Li et al., 2016in 1cu-a and 2cu-a postfurcal, and from Amboserphus Li et al., 2016and Yanliaoserphus Shih et al., 2011in 1cu-a postfurcal and 2cu-a antefurcal (Li et al. 2016).Furthermore, the position of the Rs+M forking in the forewing could be taken as a key feature.The forking of Rs+M is located one-third of the distance between 1m-cu and 2r-rs in Juraserphus gen.nov, whereas it is about one-fi fth of this distance in Mesoserphus Kozlov, 1968, Sinoserphus Shih et al., 2011and Basiserphus Li et al., 2016, and  The ovipositor of Mesoserphidae demonstrates signifi cant variations, especially in its length, among the fossils described.The ovipositor in Juraserphus gen.nov. is similar to the one in Novserphus Li et al., 2016 andOzososerphus Li et al., 2016 in being short, extending beyond the metasomal apex.In contrast, the ovipositor in some other genera (for example, Apiciserphus Li et al., 2016, Amboserphus Li et al., 2016, Udaserphus Rasnitsyn, 1983and Choriserphus Li et al., 2016) does not extend beyond the metasomal apex.On the other hand, Sinoserphus Shih, Feng & Ren, 2011(especially S. grossus Shih, Feng & Ren, 2011;S. fl exilis Shih, Feng &Ren, 2011 andS. wui Shih, Feng &Ren, 2011) has a much longer ovipositor, albeit not exceeding half of the metasomal length.Furthermore, the ovipositor in Mesoserphus Kozlov, 1968 is longer than the metasoma.
approximately one half in Amboserphus Li et al., 2016 and Beipiaoserphus Zhang & Zhang, 2000.ZHENG Y. & CHEN J., Juraserphus modicus gen.et sp.nov.from the Middle Jurassic of China