Platyxyela tenuis, Zheng, Yan, Hu, Haiyan, Chen, Dong, Chen, Jun, Zhang, Haichun & Rasnitsyn, Alexandr P., 2021

Zheng, Yan, Hu, Haiyan, Chen, Dong, Chen, Jun, Zhang, Haichun & Rasnitsyn, Alexandr P., 2021, New fossil records of Xyelidae (Hymenoptera) from the Middle Jurassic of Inner Mongolia, China, European Journal of Taxonomy 733 (733), pp. 146-159 : 150-152

Platyxyela tenuis sp. nov.

urn:lsid:zoobank.org:act:62A596B3-6015-4A3F-A55D-694B33EDC5B7

Figs 2–3

Diagnosis

Forewing long (7.9 mm in length), ovipositor sheath as long as M+Cu and strongly narrowed toward acute apex.

Etymology

The specific name tenuis , thin, feminine gender of the Latin, referring to the thinness and delicateness of the body.

Type material

Holotype, female, NND0176 with well-preserved body, wings complete but legs incomplete; NIGP.

Locality and horizon

Daohugou Village, Wuhua Township, Ningcheng County, Chifeng City, Inner Mongolia , China, Jiulongshan Formation, Middle Jurassic (Callovian-Bathonian boundary).

Comparison

Platyxyela tenuis sp. nov. is without pterostigma sclerotised completely, 1-Rs obviously shorter than 1-M and 1 m-cu half as long as 3-Cu, which indicate the position of the new species in Xyelinae , Liadoxyelini . This new species differs from P. unica in forewing length (7.9 mm vs 12.3–16.5 mm in P. unica ), ovipositor sheath length and shape (ovipositor sheath relatively much longer and slowly narrowing to rounded apex in P. unica ).

Description

Female sawfly in ventral view with approximately complete wings and full body. Head large and nearly round; eyes somewhat infuscated; antenna ca 2.7 times as long as width of head, scape about three times as long as pedicel, pedicel short, 0.11 times as long as 1 st flagellomere, the latter thickened and elongated, but obviously shorter than flagellum; flagellum with at least eight segments, each longer than wide.

Thorax slightly wider than head. Propleura large, mesonotum with notauli distinct and complete, medial mesoscutal line long and thin, mesoscutellum strongly elevated. Mesopleuron smooth, without discernible wrinkles.

Forewing with pterostigma sclerotised basally only; pterostigma narrow and nearly half as wide as cell 2r; costal area obviously dilated proximad of base of Rs; Sc with two branches, Sc1 merging with C beyond origin of Rs, Sc2 short and almost vertical, meeting R before origin of Rs; Sc2 nearly equal to 1-Rs and the latter distinctly shorter than 1-M; 3-M about 3 times as long as 2-M; R strongly curved before origin of Rs and slightly thickened before pterostigma; cross vein 1r-rs subparallel to 2r-rs and 0.8 times as long as it; base of 2r-rs 0.7 times as distant from apex of pterostigma as from base of 1r-rs; Rs+M at least six times as long as 1-Rs; section of Rs between 1r-rs and 2r-rs arched toward lower margin of forewing, end of Rs1 closer to pterostigma than to Rs2; M+Cu sinuate; 1m-cu 0.7 times as long as 2-Cu and half as long as 3-Cu; 2m-cu inclined towards wing base and half as long as 4-Cu; length proportions of cells 1r: 2r: 3R: 4r: 1mcu: 2mcu = 1.8: 0.9: 1.2: 1.9: 1.7:2.1.

Hindwing with 1r-m long, meeting Rs it is very base; 1-M ca 0.3 times as long as 1r-m; m-cu not reaching 3r-m for about half of its (m-cu) length; cell 1cu long and widened at origin of M; cu-a arcuate basally; cell 1a slightly shorter than cell cua; M and Cu with free ends not reaching wing margin, 1A with no free end; 3A almost as long as M+Cu.

Foreleg thin and short. Midleg femur ca 4.8 times as long as wide, tibia slightly shorter than femur, tarsus with basitarsus as long as three following segments combined; first segment elongated and fourth segment shortest. Hindleg longer and wider than midleg, coxa long, femur ca 5.3 times as long as wide, tibia 1.25 times as long as femur and nearly ¾ as wide as femur, tarsus with four preserved segments, apparently similar to mid one in proportions.

Abdomen with nine visible segments; ovipositor sword-shaped, with sheath twice as long as valvifer II.

Measurements

Body length (excluding ovipositor sheath) 7.8 mm long. Head width 1.2 mm, length 1.1 mm. Antennae not shorter than 3.2 mm, third antennal article ca 1.5 mm. Length of forewing ca 7.9 mm; maximum width of forewing ca 2.9 mm. Thorax 1.8 mm in length and abdomen 5.1 mm in length. Length of ovipositor 3.6 mm, with valvifer II 1.2 mm and ovipositor sheath 2.3 mm.

Figures

Fig. 2. Photograph of Platyxyela tenuis sp. nov. Holotype, NND0176. Ruler unit (top right): 1 mm.

Fig. 3. Line drawings of Platyxyela tenuis sp. nov. A. Habitus, holotype. B. Left forewing. C. Left hindwing. Symbols: cx2, cx3 = mid and hind coxae; f 1, f 2, f 3 = fore, mid and hind femur; fl = flagellum; md = mandible; no = notaulus; oc = eye; pd = pedicel; pl 2 = mesopleuron; sc = scape; ta1, ta2, ta3 = fore, mid and hind tarsus; ti 1, ti 3 = fore and hind tibia; tr1, tr2, tr3 = fore, mid and hind trochanter; v3 = ovipositor sheath; vr2 = second valvifer; 1–9 = abdominal segments; III = enlarged third antennal segment; venational symbols standard, names of wing cells italicised. Scale bars: 1 mm.