Big and beautiful : the Megaxyela species ( Hymenoptera , Xyelidae ) of East Asia and North America

Megaxyela Ashmead, 1898 comprises 13 species, four of which are described as new and one is removed from synonymy: Megaxyela euchroma Blank, Shinohara & Wei sp. nov. from China (Zheijang), M. fulvago Blank, Shinohara & Wei sp. nov. from China (Hunan, Jiangsu, Zhejiang), M. inversa Blank & D.R. Smith sp. nov. from the USA (West Virginia), M. langstoni Ross, 1936 sp. rev. from the eastern USA, and M. pulchra Blank, Shinohara & Sundukov sp. nov. from China (Hubei, Jilin, Liaoning, Shaanxi, Tibet), South Korea (Kangwon-do) and Russia (Primorskiy Kray). The male European Journal of Taxonomy 348: 1–46 ISSN 2118-9773 https://doi.org/10.5852/ejt.2017.348 www.europeanjournaloftaxonomy.eu 2017 · Blank S.M. et al. This work is licensed under a Creative Commons Attribution 3.0 License. R e s e a r c h a r t i c l e urn:lsid:zoobank.org:pub:56D8BC29-3C29-4EE8-8633-B997784CA00A


Introduction
Adults of Megaxyela Ashmead, 1898 represent the most colorful and the largest extant xyelids with a body length of up to 14 mm.Despite their conspicuousness, collection records are comparatively seldom.The distribution of the extant species of Megaxyela covers the eastern part of the Nearctic and the southeastern part of East Asia (Shinohara 1992;Smith & Schiff 1998;this paper).Outside this area, the Oligocene † Megaxyela petrefacta Brues, 1908 was recorded from western North America from deposits of Florissant (Colorado, USA ;Brues 1908;Zhelochovtsev & Rasnitsyn 1972).A second fossil species, † M. yaoshanica Zhang, 1989 from deposits at Shanwang (Shandong, China) dates back to the mid-Miocene (Zhang 1989).Fossils of Megaxyela are young in comparison with the earliest Megaxyelinae from the Upper Jurassic (e.g., Rasnitsyn 1966Rasnitsyn , 2008;;Zhang & Zhang 2000) and the oldest Xyelidae from the Late Triassic (e.g., Kopylov 2014;Lara et al. 2014).
Larvae of Megaxyela are external feeders of Juglandaceae.The East Palaearctic M. gigantea Mocsáry, 1909 feeds on the leaves of Juglans Linné and Pterocarya Nuttal ex Moquin.Saito (1941) reported on the oviposition behavior of this species.Taeger et al. (2010: pl. 21, fig. 3) depicted an unidentified larva found in Yunnan, China, feeding on J. sigillata Dode.The Japanese M. togashii Shinohara, 1992, which is associated with J. ailanthifolia Carrière, represents the first Eurasian species for which the larva and ecological traits have been described in detail (Shinohara et al. 2017).The North American M. aviingrata (Dyar, 1898), M. langstoni Ross, 1936 and M. major (Cresson, 1880) have also been found on Juglandaceae like pecan (Carya illinoinensis (Wangenh.)K.Koch) and butternut (Juglans cinerea L.) (e.g., Dyar 1898a; Smith 1967;Smith & Schiff 1998).Megaxyela major has been reported as a minor pest of cultivated pecan trees in Texas (Ree 2012(Ree , 2014)).Collection circumstances of Proctorenyxa incredibilis Kozlov, 1994 on Juglans mandshurica Maxim. in the Russian Far East indicate that Megaxyela might be the hosts of Proctorenyxidae, an enigmatic family of the parasitic Proctotrupoidea represented by only two species (Lelej 2012;Kim et al. 2016).
Five Nearctic and three East Palaearctic species were previously known for the extant fauna (Shinohara 1992;Smith & Schiff 1998).Here, we add four new species, M. euchroma Blank, Shinohara & Wei sp.nov., M. fulvago Blank, Shinohara & Wei sp.nov., M. inversa Blank & D.R. Smith sp.nov.and M. pulchra Blank, Shinohara & Sundukov sp. nov., and we remove M. langstoni from synonymy.We review Megaxyela with focus on the Old World taxa and summarize data on larval hosts and distribution.The analysis of COI barcodes is used to complement morphological studies.

Measurements
The following measurements have been taken: Length of body: distance between interantennal area and tip of tergum 9+10 in females (ovipositor not included in measurement), between interantennal area and tip of hypopygium in males.Length of fore wing: distance between anterior edge of tegula and distal edge of wing.POL, postocellar line: shortest distance between medial edges of posterior ocelli.OOL, ocellus-ocular line: shortest distance between lateral edge of posterior ocellus and nearest edge of neighboring eye.OCL, ocellus-occipital line: shortest distance between posterior edge of posterior ocellus and posterior edge of head.POL, OOL and OCL are each taken in vertical view on the measured line.Distance of antennal toruli: shortest distance between medial (sclerotized) edges of toruli.Distance between eye and antennal torulus: shortest distance between lateral (sclerotized) edge of torulus and medial edge of eye.Width of frons: distance between medial edges of eyes at level of dorsal edges of antennal toruli.Length and width of eye: longest distance between dorsal/ventral and medial/posterior edge of eye in obliquely lateral view (respective edges in same focus plain).Length of malar space: shortest distance between ventral edge of eye and edge of mandibular concavity.Number of articles of antennal filament: completely and incompletely separated articles counted as single articles.This applies in particular to the distal two articles that are sometimes separated by a suture on the posterior/anterior side but continuous anteriorly/posteriorly.More rarely, malformed articles with partial separation occur in the medial section of the filament.Length of synantennomere 3, antennal filament, article 3 of maxillary palp, metafemur, metatibia, longer metatibial spur: distance between proximal and distal end of these articles, in the parallel-sided synantennomere 3 and antennal filament taken parallel to outer edge, in the maxillary article 3 along lateral surface, in the metafemur parallel to ventral edge from basal to dorsal tip.Length of metatarsomeres: measured along dorsal edge of tarsomeres, for metatarsomere 1 distance between tip of metatibia and dorsal distal edge of metatarsomere 1, for metatarsomeres 2-5 from tip of tarsomere 1 to tip of tarsomere 5. Width of metatarsomere 1: largest width in lateral view between dorsal and ventral surfaces of article, setae not taken into account.Length of ovipositor sheath: combined length of valvifer 2 and valvula 3, both measured as straight lines along ventral edge of the sclerite (Fig. 1E).Width of valvula 3 of ovipositor sheath: greatest distance between dorsal and ventral edge of valvula 3 (Fig. 1E).

Host nomenclature
The nomenclature of the taxa of Juglandaceae, which are considered as larval hosts of Megaxyela, follows The Plant List (2013).

Barcoding
Treatment of the specimens with DEI-GISHym numbers 5751-5752 of Megaxyela fulvago sp.nov., 18503-18504 of M. pulchra sp.nov.: for DNA extraction, the single leg of these adults was removed and submitted to the Canadian Centre for DNA Barcoding (CCDB) in Guelph, Canada, where the DNA sequencing was performed (see Blank et al. 2013 andSchmidt et al. 2017 for details).Sequencing of M. gigantea (2 ♀♀, 1 ♂ from 1996, 2002), M. parki Shinohara, 1992Shinohara, (3 ♀♀ from 1990Shinohara, , 1993) ) and of European Journal of Taxonomy 348: 1-46 (2017) additional specimens of M. pulchra sp.nov.(2 ♀♀ from 1994, 1998) was unsuccessful, supposedly due to the age of the pinned material, relaxing in a moist chamber before mounting, and supposedly due to storage in a collection environment where 1,4-dichlorobenzene is continuously applied for pest control.Data of the analyzed specimens are accessible through the website of Barcode of Life Data Systems (BoldSystems, http://www.boldsystems.org).
Treatment of the specimens with DEI-GISHym numbers 22355, 22513 and 22515 of Megaxyela euchroma sp. nov., 5237, 5239 and 30883 of M. fulvago sp. nov., 18507 of M. gigantea, 30796 of M. langstoni, 30767 and 30797 of M. major, 22347, 22349 and 86249 of M. pulchra sp. nov., 22354 and 22521 of M. togashii: total genomic DNA was extracted from one leg or from the genital capsule (without mechanical disruptions) of these specimens using the E.Z.N.A. Tissue DNA Kit (Omega Bio-tek Inc., Norcross, USA) according to the manufacturer protocol for tissue DNA, except some smaller modifications.Lysis time was at least 3 hours for the legs and 4 hours for the genital capsules.Elution was performed twice with 100 µl Elution Buffer each.A partial fragment (658 bp) of the mitochondrial cytochrome c oxidase subunit I (COI) gene was amplified by PCR using the primers SymF2 (5'-TTTCAACAAATCATAAARAYATTGG-3') and SymR2 (5'-TAAACTTCTGGRTGTCCAAARAATCA) (Prous et al. 2016).Amplifications were performed in 15 µl reactions containing 7.5 µl 2 × Qiagen Multiplex PCR Master Mix (Qiagen, Hilden, Germany), 0.2 µM of each primer, RNase-free water and template DNA (1-3 µl).Amplification conditions were as follows: initial PCR activation step at 95°C 5 min, 38 cycles of 30 s denaturing at 95°C, 90 s annealing at 46°C, 1 min extension at 72°C, followed by a final extension of 30 min at 68°C.PCR products were visualized on a 1.4% agarose gel stained with Gel Red (0.1, Biotium, Hayward, USA).PCR products were purified with Exonuclease I and FastAP Thermosensitive Alkaline Phosphatase (Life Technologies, Darmstadt, Germany) and sequenced on an ABI3730XL sequencer using Big Dye v. 3.1 Terminator Kit (Thermo Fisher Scientific, Darmstadt, Germany) by Macrogen Europe (Amsterdam, the Netherlands.Sequencing was performed with the same primers used for amplification.Sequences were checked, manually edited using Geneious 9.1.2(Kearse et al. 2012) and aligned using BioEdit 7.2.5 (Hall 1999).
All sequences of the Megaxyela species have been deposited in GenBank.The individual accession numbers are listed in Table 1.For the calculation of the cladogram we considered two specimens of Macroxyela ferruginea (Say, 1824) (GenBank accession numbers EF032211.1,KF936523.1) in addition.
The evolutionary history was inferred by using the Maximum Likelihood method conducted in MEGA7 (Kumar et al. 2016).The best-fitting model for the analysis, the Jukes-Cantor model (Jukes & Cantor 1969), was retrieved by jModelTest 2.1.7(Darriba et al. 2012).It was run with 1000 bootstrap replications.Bootstrap values > 50% are shown on the ML tree next to the concerned nodes.The tree is drawn to scale, with branch lengths measured as the number of substitutions per site.The analysis involved 22 nucleotide sequences.There were a total of 658 positions in the final dataset, and all sites were used.The number of base differences per site (p-distance) between sequences was calculated.Codon positions included were 1st+2nd+3rd+Noncoding.All ambiguous positions were removed for each sequence pair.

Imaging
Digital images of the specimens were taken with a Leica DFC450C camera attached to a Leica M205 C stereo microscope.Lighting was either from the high diffuse dome illumination Leica LED5000 HDI or from a cold light source attached to double light guides which produced indirect illumination by diffused light reflected from the inner surface of a styrofoam cup set up around the specimen.A grey card was used as the background and for white balance.Images from preparations of the penis valves and an ovipositor were taken from an Olympus BX50 compound microscope with a Leica DFC450 C camera.For this purpose, the specimens were mounted in glycerin temporarily.Composite images with an extended depth of field were created using the software CombineZP (Hadley 2010).Large specimens exceeding the field of view of the camera were stitched with Image Composite Editor (Microsoft Research 2015).

BLANK S.M. et al., Megaxyela of East Asia and North America
Table 1.COI sequences of Megaxyela species analyzed in this work, with specimen identifier (DEI-GISHym number), sex, collection data (including deposition of the voucher), length of COI-5P sequence (bp), and GenBank accession number.
The images were processed with PhotoImpact (Ulead Systems Inc.) and Adobe Photoshop CS4 (Adobe Systems Inc.) and mounted with CorelDraw (Corel Co.).
The distribution map was prepared from draft maps produced by Carto Fauna-Flora 1.2 (Barbier & Rasmont 1996) and was enhanced with help of Adobe Photoshop CS4.

Specimen citation
Original labels of type specimens are quoted literally between "…".Data for paratypes and additional material is listed in a standardized way.Additional explanations and interpretations, like geographic coordinates not written on the collection label, are given in square brackets […].

Comparative material examined
Below we discuss the individual species as far as additional information has been gained since the revisions of Shinohara (1992) and Smith & Schiff (1998).We studied the following material of Nearctic species, which is not listed in detail below: Megaxyela alisonae D.R. Smith & Schiff, 1998

Remarks
The above data from West Virginia represent a new state record.Among others, the species has been found in the neighboring states of Pennsylvania and Virginia (Smith & Schiff 1998).

Diagnosis
This species is unique upon the black head bearing narrow yellow lines along inner and outer orbits and a linear yellow spot on vertex (Fig. 3A-B, D, F-G), and the presence of ctenidia along the annuli of the ovipositor (Figs 1F, 12A).It is separated from other Eurasian species by the metallic blue shine of dark colored body parts (Fig. 3A-G), the laterally black terga 2-4 (Fig. 3A-E; only the ventral margins of the terga bear a narrow longitudinal white line ventrally, Fig. 3C, E), the almost completely black valvula 3 of the ovipositor sheath (Fig. 11A), the black hypopygium of the male (Fig. 3E), and the large and irregular teeth of the upper edge of the valviceps (Fig. 13A).

Etymology
The species name is a noun derived from ancient Greek ευ-(eu-, beautiful) and χρωμα (chroma, color).BLANK S.M. et al., Megaxyela of East Asia and North America orbits, one along ventral half of outer orbits and along ventral edge of eye; clypeus along anterior margin, labrum, mandibles and most of other mouthparts red brown to white (similar to Fig. 3F-G).Antenna black.Tegula, dorsolateral corner and narrow lateroventral margin of pronotum yellow white.Abdominal terga 1-8 with narrowly white distal margins, lateroventral portions of terga 2-7 with continuous 50-100 µm wide white stripe along ventral margin (Fig. 3C).Abdominal sterna 2-7 broadly white along lateral and distal margins (Fig. 3C).Valvifer 2 of ovipositor red brown in basal half, black in distal half, valvula 3 black with brown tip, membrane in between valvifer 2 and valvula 3 white (Fig. 11A).Fore and mid legs red brown, coxae predominantly black from bases, trochanters partly white.On hind leg, basal third of coxa laterally black, distal portion red brown, trochanter and trochantellus white, femur predominantly red brown in basal half, predominantly black in distal half, tibia black, tarsus white, tarsomere 1 weakly infuscate in basal third (Fig. 3A-C, H-I).Wings weakly brown stained, venation brown, pterostigma black (Fig. 3D-E), sometimes brown (Fig. 3A-B, immature specimens?).

Male
Color.Similar to female (Fig. 3D-G, K).Subgenital plate and genitalia black.

Remarks
Megaxyela euchroma sp.nov. is characterized by a number of unique characters (see Diagnosis).All other East Asian species are completely white on the ventral portion and partly on the dorsolateral portion of terga 2-3 or 2-4.In these cases, the white band on terga 2-3 or 2-4 is much wider than on the subsequent terga.The head is more extensively yellow or red brown, at least on the gena in M. gigantea, M. pulchra sp.nov.and M. togashii, or the eye is completely surrounded by black except for the malar space in M. parki.Megaxyela euchroma sp.nov.and M. parki share the white metatarsus, which is black in the other East Asian species.
With respect to the white pattern of the terga, M. euchroma sp.nov. is similar to the North American M. alisonae, M. bicoloripes, M. inversa sp.nov.and M. tricolor (Smith & Schiff 1998).Megaxyela alisonae and M. bicoloripes have a white metatarsus similar to M. euchroma sp.nov., while M. tricolor has a black metatarsus.In the Nearctic species, a yellow white pattern on the orbits and the vertex, similar to that of M. euchroma sp.nov., is absent.Megaxyela alisonae and M. bicoloripes bear an extensive red brown pattern on thorax and abdomen, which is absent in M. euchroma sp.nov.Megaxyela inversa sp.nov.differs in the shape of the ovipositor sheath, which is straight dorsally in the basal and the medial sections, vs convex in M. euchroma sp.nov.
The analysis of the COI sequences supports the monophyly of the studied specimens by a bootstrap of 100%.The maximum intraspecific variation is 0.3%.The nearest neighbor, M. fulvago sp.nov., is placed at a distance of 12.7% (Fig. 2).
All the available adults were found on the undergrowth of open forests during cloudy weather.There were Juglans trees nearby and new shoots of leaflets were beginning to grow.

Diagnosis
The red brown head, prothorax and mesothorax are unique to this species.

Etymology
The Latin noun fulvago indicates the predominantly pale brown color of this species.

Description Female
Color.Body red brown with black-and-white pattern, black parts partly with bronze tinge (Fig. 4A).Head and thorax red brown (specimen 30882 with diffuse transverse stripe on vertex -artifact?),posterior half of metanotum and ventral half of metepisternum infuscate.Scape red brown, pedicel black, flagellum dark brown.Abdomen in dorsal view black with continuous white bands laterally on terga 2-4, each 0.15-0.20 × as wide as tergal width, tergum 8 with narrower lateral white band, ventral portions of terga 2-4 and 8 completely white, terga 5-6 narrowly and tergum 7 broadly white along ventral margin, terga 9+10 brown with small dark spot dorsolaterally.Sterna white.Valvifer 2 and valvula 3 red brown, membrane between valvifer 2 and valvula 3 pale (Fig. 11B).Fore and mid legs pale red brown.On hind leg, coxa red brown, infuscated laterally in middle and dorsally, trochanter and trochantellus pale red brown, femur brown dorsally and red brown ventrally, tibia and tarsus brown.Wings weakly yellow stained, venation and pterostigma yellow brown.

Male
Color.Similar to female (Fig. 4E-G).Metepimeron red brown or predominantly infuscate.Ventral portions of terga 5-7 predominantly white.Subgenital plate and genitalia red brown.On hind leg, coxa sometimes completely black laterally, trochanter and trochantellus red brown, femur black dorsally and medially, dark red brown ventrally and laterally, tibia and tarsus black (Fig. 4C-D).

BLANK S.M. et al., Megaxyela of East Asia and North America
Subgenital plate bluntly pointed at apex.Valviceps of penis valve distally parabolically rounded, basal 0.3 of upper side expanded to a round lobe coiled laterally, medial 0.3-0.8 of upper edge shallowly convex, with numerous small teeth.Distal 0.7 of valviceps with long setae, most dense in medial lower portion of valviceps (Fig. 13B).

Remarks
Megaxyela fulvago sp.nov. is most similar to M. gigantea regarding color and structure.In both species, terga 2-4 are extensively white on the dorsolateral and ventral portion.This pattern is absent in M. euchroma sp.nov.and in most of the Nearctic species.White is present on the dorsal side of only terga 2-3 in M. parki, M. pulchra sp.nov.and M. togashii, as well as in the Nearctic M. major.Megaxyela fulvago sp.nov.and M. gigantea share the dull, minutely areolate and shallowly pitted face.A rugose surface structure is absent from the frons, which has been observed in the other East Asian species.Megaxyela fulvago sp.nov.and M. gigantea are primarily discriminated by color: head, prothorax and mesothorax are completely red brown in M. fulvago sp.nov., but these parts bear an extensive dark brown to black pattern in M. gigantea.The antennal filament of females is longer in M. fulvago sp.nov.(1.1 mm) than in M. gigantea (0.8 mm), and sometimes it is subdivided into fewer articles in M. fulvago sp.nov.(♀: 8-9; ♂: usually 8-9) than in M. gigantea (♀: 9; ♂: 9-10).The relative distance of POL : OOL : OCL differs weakly in males (1.0 : 1.6-1.7[-1.9]: 1.7-1.9[-2.0]and 1.0 : 1.8-2.0: 2.0-2.2,respectively).The metatarsomere 1 of males is 4.9-5.5 × as long as wide in M. fulvago sp.nov.but 4.6-5.0× in M. gigantea.The female of M. fulvago sp.nov.falls into the range of variability of M. gigantea regarding these two characters.
The COI sequences group the specimens identified as M. fulvago sp.nov.by morphology into a clade which is supported by a bootstrap of 97%.This clade additionally includes a specimen of M. gigantea.Supposedly this placement is an artefact caused by the short sequence length (261 bp) of this specimen.The maximum intraspecific variation within M. fulvago sp.nov. is 0.8%.Megaxyela togashii is placed at a minimum pairwise distance of 7.6% (Fig. 2).
The specimens from Mount Yunshan were collected on a sunny day flying around birch trees with lots of catkins shedding pollen.Pollen feeding of adults is well known for Xyela species, which bear distally modified and usually extended maxillary palps (Burdick 1961).A similar behavior is unknown for adult Macroxyelinae.Although M. major has been caught from catkins of willow (Bridwell 1906) and pollen has been identified from the intestine of two fossil Macroxyelinae species (Krasilov & Rasnitsyn 1982), Megaxyela is not specialized in pollen feeding but is facultatively palynivorous, because the labiomaxillar complex exhibits no particular modifications for the uptake of pollen as in Xyelinae.Takeuchi (1940) and Maa (1949) referred to the specimens of M. gigantea collected in "Chinkiang [= Zhenjiang], Prov.Kiangsu [= Jangsu Sheng]" deposited in the collection of the Musée Heude, Shanghai at that time.Major parts of this collection have been incorporated into IZCAS, Beijing (Yang Ganyan, personal communication).The two females and one male collected in "Chinkiang" in 1918 could be identified as M. fulvago sp.nov.with help of photos kindly provided by Yang Ganyan.An additional female from "Chinkian" (3 May 1936, E. Suenson leg.), which we identified as M. gigantea prior to the recognition of M. fulvago sp.nov., is kept at INHS.Mocsáry, 1909 Figs

Host plant
European Journal of Taxonomy 348: 1-46 (2017) In South Korea, A. Shinohara captured a male of M. gigantea together with 3 ♀♀, 2 ♂♂ M. pulchra sp.nov.from the same J. ?mandshurica tree at end of May and beginning of June 2002.

Remarks
Megaxyela gigantea is similar to species with the terga 2-3 or 2-4 laterally extensively white (dorsally black in M. euchroma sp.nov.and in the Nearctic species except for M. major).It is unique among the East Asian species in the predominantly red brown head (predominantly black in M. parki, pale yellow color and less extensive in M. togashii) bearing a large infuscate spot on face and vertex (completely red brown in M. fulvago sp.nov.), which does not extend to the antennal toruli ventrally (spot extending to toruli in M. pulchra sp.nov.).As in M. fulvago sp.nov., the surface of the face is minutely areolate and bears scattered, shallow, 50 µm large pits (face rugose in other East Asian species at least laterally).The dorsal side of terga 2-4 is white laterally for 0.15-0.20 × the tergal width in M. gigantea and M. fulvago sp.nov., whereas the white marks are generally narrower in M. parki or narrower at least on tergum 4 in M. pulchra sp.nov.and M. togashii.
The single specimen studied genetically is placed within the group, which otherwise comprises M. fulvago sp.nov., but we interpret this placement as an artefact caused by the very short sequence length of M. gigantea.Morphological results indicate two separate species.Blank & D.R. Smith sp. nov. urn:lsid:zoobank.org:act

Diagnosis
This species is unique by the very long ovipositor sheath with the dorsal outline of valvula 3 straight and the ventral outline convex, and the ovipositor curved dorsally along its longitudinal axis.

Etymology
The Latin adjective inversus (fem.inversa) indicates the shape of the ovipositor, that, in contrast to other Megaxyela species, is dorsally curved.

Male
Unknown.
Among Nearctic Megaxyela this species is most similar to M. bicoloripes and M. tricolor by the slender metatarsus and the red brown metafemur bearing an extensively infuscate apex.It is readily distinguished from all other Megaxyela species by the outline of the basal and medial portion of valvula 3, which in lateral view is straight dorsally and evenly curved ventrally.The remaining Megaxyela species have either both the dorsal and the ventral outlines of valvula 3 curved, or the dorsal outline is curved and the ventral straight (Fig. 11A-C, 11E-H; Smith & Schiff 1998: figs 7-11).
The paratype is presumably from North America because of its discovery in a US collection and the holotype is from West Virginia.Morphometry and figures are from the paratype since the specimen used as holotype was discovered too late to include in this paper.

BLANK S.M. et al., Megaxyela of East Asia and North America
Megaxyela langstoni Ross, 1936

Host plant
Pecan (Carya illinoinensis; cited as "Carya pecan A. & G." by Ross 1936) and possibly additional species of Carya (Dyar 1898b as M. major; Yuasa 1923 as Megaxyela sp. 1).Supposedly also the photo by Ree (2014) of gregarious larvae of M. 'major' feeding on pecan refers here.Smith (1978Smith ( , 1979) ) treated Megaxyela langstoni as a synonym of M. major.With some reservation, Smith & Schiff (1998) discussed differences in behavior, color and morphology as possible intraspecific variation.Here we reinstate M. langstoni sp.rev.as a valid species.The analysis of the barcoding region of three females, all originating from a collection site in Oklahoma, resulted in two clades (DEI-GISHym 30796 and 30767 + 30797, respectively) separated by a minimum pairwise distance of 13.5%, while the two specimens included in the clade 30767 + 30797 are separated by a mimimum pairwise distance of only 0.3% (Fig. 2).This observation is paralleled by different coloration of the adults corresponding with the type material and the descriptions of M. langstoni and M. major: Specimen 30796 agrees with M. langstoni in the predominantly red brown terga and the basally black pterostigma (Fig. 7A), while the specimens 30767 + 30797 agree with M. major in the dorsally predominantly black terga and the unicolorous yellow pterostigma (Fig. 7G).

Remarks
Several specimens included in the type series of M. langstoni were reared from the pecan Carya illinoinensis (Ross 1936).Ross (1936) also referred to the descriptions of larvae of M. major by Dyar European Journal of Taxonomy 348: 1-46 (2017) (1898b) and Yuasa (1923).Dyar described the larvae as "gregarious on the young leaves of hickory" [= Carya spec.].Yuasa (1923) noted "on hickory and pecan".If the association of larvae described by Yuasa as "Megaxyela sp.1" with M. major by J.M. Langston and H.H. Ross is correct, M. major is a "solitary feeder on pecan and some other hickories" (Ross 1936).Citing M. major, M. langstoni has been listed as a pest of pecan in Texas, but "in most cases sawfly damage is just 'visual discomfort'

Remarks
Megaxyela parki belongs to the group of East Asian species with extensively white terga 2-4.Among these species, it is unique in the completely red brown tergum 7 (black and laterally/ventrally white in other species).It is also easily identified by its comparatively short antennae with the antennal filament comprising 6-7 articles, long valvula 3 of the ovipositor sheath, almost completely black head, red brown antennae, and yellow white metatarsus.
The previously unknown male is similar to the female in color.Both male and female bear a much less dense hair cover on the posterior tarsi than other East Asian taxa.The larval host is still unknown.Blank, Shinohara & Sundukov sp. nov. urn:lsid:zoobank.org

Diagnosis
Megaxyela pulchra sp.nov. is characterized by the following unique combination of characters: frons above the antennal toruli rugulose, head with black spot extending from postocellar area and vertex to the antennal toruli, pterostigma yellow brown and infuscate basally and anteriorly, pectus red brown, hypopygium of male red brown.Megaxyela pulchra sp.nov.differs from the Nearctic species of Megaxyela, except for M. langstoni and M. major, and from the East Asian M. euchroma sp.nov. in the presence of a broad, continuous white band dorsolaterally and ventrally on terga 2-3.Such extensive white pattern on the basal terga is absent in most North American species, which at most bear a narrow white stripe along the ventral margin of the terga as observed in M. alisonae, M. bicoloripes and M. tricolor (Smith & Schiff 1998;Blank, unpublished data).Megaxyela pulchra sp.nov.differs from M. langstoni and M. major, for example, in the black metatarsus (yellow white in M. major) and in the stout valvula 3 of the ovipositor sheath (Fig. 11G; slender in M. major, see Smith & Schiff 1998: fig. 7).
Morphological differences between M. pulchra sp.nov.and M. togashii are faint: the mesoscutellum is homogeneously areolate and flat in M. pulchra sp.nov., but areolate in the middle, with a wide stripe along lateral and anterior margin rugose with areolate microsculpture in M. togashii; the distance between the toruli is 0.95-1.05× as wide as the distance between torulus and eye margin in M. pulchra sp.nov.♀ but 1.20 × in M. togashii ♀; the malar space is 0.6-0.7 × as wide as the distance between toruli in M. pulchra sp.nov.but 0.4 in M. togashii.The two species exhibit different tendencies of coloration: the face, ventral part of mesepisternum and mesosternum, and dorsal portion of tergum 4 are paler in M. pulchra sp.nov., while the posteriolateral ridge of the mesoscutal lateral lobe is paler in M. togashii.The subgenital plate of the male M. pulchra sp.nov. is red brown as in M. gigantea, whereas it is white in the male M. togashii.
The anterior margins of the sterna always bear a pair of large black marks in M. togashii.Such marks are absent in other Megaxyela (see Smith & Schiff 1998 for Nearctic species) except for M. pulchra sp.nov., whose female rarely bears small marks on the sterna.These spots are a putative apomorphy of the vicariant species M. pulchra sp.nov.from the East Asian mainland and M. togashii from Japan.Among Xyelidae, similar pairs of sibling species (or at least morphologically very similar species) with East-Asian mainland / Japanese vicariance have been observed among Xyela species associated with Japanese red pine, Pinus densiflora Siebold & Zuccarini (Blank et al. 2005).
The specimens studied genetically are supported by a bootstrap of 100%.The maximum intraspecific variation is 3.1%.The nearest neighbor, M. togashii, is placed at a minimum pairwise distance of 8.0%.Zhelochovtsev & Zinovjev (1995), Lelej & Taeger (2007) and Lelej (2012) listed M. gigantea for the Russian Far East, but at least the female from Voroshilovskiy Rayon identified by A. Zinovjev refers to M. pulchra sp.nov.Sundukov (2009) noted a specimen from Lazo differing from M. gigantea, which is included as a paratype of M. pulchra sp.nov.here.The specimens published by Shinohara (1992) for South Korea all belong to M. gigantea.Shinohara, 1992 Figs 10A-J, 11H, 12H, 13F

Remarks
Megaxyela togashii is the correct name for the Japanese species, which has been called M. gigantea by Takeuchi (1937), Togashi (1965) and subsequent authors up to Shinohara (1992).This species is most similar to M. pulchra sp.nov. in structure and color.See Remarks there for differentiation of these two species.
The clade including two genetically studied adults from Honshu, which were collected on the same site, is supported by a bootstrap of 100%.The maximum intraspecific variation is 1.4%.Under a wider geographical scope, Shinohara et al. (2017)

Remarks
This is the first state record for West Virginia.The species has been found in Connecticut, Illinois, Kansas, Missouri and in Ontario (Smith & Schiff 1998).
Identification key to the species of Megaxyela 1 Valvula 3 of ovipositor sheath dorsally straight, ventrally evenly convex in basal and medial portion Fig. 11D).

Discussion
Megaxyela is a morphologically well-defined genus of Macroxyelinae that also includes two Nearctic species of Macroxyela in the extant fauna.The carina along the inner orbit (e.g., Figs 3F-G, 4G, 6C, 8E) is a unique character of Megaxyela among Xyelidae.In addition, the comparatively distal position of vein Sc2 of the fore wing (Figs 1A-B, 6F) and the extended hind legs (e.g., Fig. 3A-B, D-E) support this taxon morphologically.In the female the long hind legs may have provided the evolutionary predisposition for a derived oviposition behavior as observed by Saito (1941) in Megaxyela gigantea (Shinohara 1992).The monophyly of Megaxyela is also corroborated by the analysis of COI sequences: the nearest neighbors Megaxyela langstoni and Macroxyela ferruginea are separated by a pairwise distance of 13.7%, which is only slightly larger than some interspecific gaps within Megaxyela (Fig. 2).
The branching of the cladogram in Fig. 2, which is based on genetic data from a restricted number of Megaxyela species, can partly be interpreted with help of morphological characters.Megaxyela fulvago sp.nov., M. gigantea, M. pulchra sp.nov.and M. togashii are included in a common clade, which is supported by the presence of bulbous areas on valvula 1 and valvula 2 of the ovipositor (Fig. 12B-C 5E).Megaxyela langstoni is very close to M. major in structure and color (Fig. 7).Although Smith & Schiff (1998) already casted some doubt, these two taxa were treated as synonyms until now.Even more surprising in the course of this study was the discovery of a very large genetic distance (13.5%) between these species, which led to the recognition of M. langstoni as a separate species.Equally large interspecific genetic gaps have been reported for Pleroneura and Xyela by Blank et al. (2013) and Schmidt et al. (2017).
BLANK S.M. et al., Megaxyela of East Asia and North America morphological characters and the phylogenetic analysis of these data is required to gain a cladogram covering all Megaxyela species.This hypothesis might help to explain the evolution of characters like the number of tarsal pulvilli, the shape of the claw, the pilosity of the metatarsus and the color pattern of the abdomen, which show striking differences among the species.Additional barcoding sequences may be particularly significant for the identification of the larvae of Megaxyela, which remain poorly known.Proper knowledge of the larvae may provide supplementary data about distribution and host associations of the species.
Successful collecting of Megaxyela very much depends on luck, and several species appear to be very rare.The only two known specimens of M. inversa sp.nov.were collected at a time interval of 121 years.For most cases, single specimens were collected from undergrowth or lower branches of various plants, resembling the collection circumstances in many other sawflies.A number of unidentified larvae have been found on lower branches at a hight of 1-5 meters.Once, more than 50 adults of M. gigantea were collected at Mt. Nogodan, Korea, in 1996 within about 30 minutes.Those adults were flying around a single, unidentified tree near a road, but no specimens were observed on other trees nearby.
A subsequent visit at this site in 1997, during exactly the same season, was unsuccessful (Shinohara, personal observations).
The record of M. fulvago sp.nov.from Hunan represents the most southern of a Megaxyela species in East Asia, extending the known distribution of Megaxyela in East Asia 600 km farther south (Fig. 14).
European Journal of Taxonomy 348: 1-46 (2017) unidentified Megaxyela larva from Gongshan (Yunnan; specimen illustrated by Taeger et al. 2010: pl. 21 fig.3) extend the known distribution area of East Asian Megaxyela more than 2500 km westwards with regard to previously published data.Juglandaceae also occur in northern Burma and India (Lu et al. 1999) as well as in more western regions of Eurasia, but Megaxyela has never been recorded from there.In the Nearctic realm, extant Megaxyela and chiefly also their hosts occur in the East, leaving a striking gap in the West of the Nearctic or in the West of the Palaearctic in view of the global distribution.The record of † M. petrefacta and † Carya florissantensis Manchester from Oligocene deposits of Florissant (Colorado) and additional records of fossil Juglandaceae from the western USA (Brues 1908;Manchester 1987) indicate that in the extant fauna both these sawflies together with their hosts exhibit a relict distribution.
A thorough phylogenetic analysis might shed light on the zoogeographic relationships of the Megaxyela species of the Old and the New World.

Fig. 2 .
Fig. 2. Phylogenetic hypothesis of Megaxyela Ashmead, 1898, based on a Maximum Likelihood analysis of the barcoding region (COI-5P) applying the the Jukes-Cantor model.Two specimens of Macroxyela ferruginea (Say, 1824) have been included as outgroup.See Material and Methods for details.Bootstrap values above 50 % are shown next to the concerning nodes.The labels of the individual specimens consist of species name, voucher number (for Megaxyela identical with the DEI-GISHym numbers used in the text, for Macroxyela GenBank accession number), sex (♀ for females, ♂ for males) or larva, country and province of origin, and sequence length.
M. et al., Megaxyela of East Asia and North America