Mesoscytina tongchuanensis Q. Zhang, Du & H. Zhang 2024, sp. nov.

Mesoscytina tongchuanensis Q. Zhang, Du & H. Zhang sp. nov. Figs 1, 2 A Type material. Holotype: No. NIGP 205761 a, b, an isolated complete tegmen, part and counterpart. Housed at NIGPAS. South of Hejifang Village, Jinsuoguan Town, Yintai District, Tongchuan City, Shaanxi Province, China. Age and horizon. Ladinian, late Middle Triassic; top of the lower Tongchuan Formation. Etymology. The specific epithet is from the city of Tongchuan, where the holotype was collected. Diagnosis. Small tegmen (6–11 mm in length), punctate, quite broad (length / width ratio less than 2.5), broadest on its middle area, with apical area contracted; postcostal area wide; costal fracture curved and single; vein R with two terminal branches; stem M partly curved, with three terminal branches, vein M 1 + 2 long; end of vein CuA 2 beyond vein CuP; terminal branches of stems RP, M and CuA not more or less parallel; crossvein cua - cup long, less curved veins M 3 + 4 and CuA 1 smoothly connected at crossvein m - cu. Clavus developed and convex, veins Pcu and A 1 forming a “ Y ” fork; color patterns small and irregular. Description. Tegmen convex with clavus attached, punctate more distinct on basal tegmen surface. Tegmen length 8.9 mm, maximum width 3.75 mm, length / width ratio 2.37. Tegmen apex asymmetric, gradually narrowed posteriorly. Costa anterior strongly arched, posterior margin more or less straight; tegmen broadest near middle part. Vein Pc + CP curved and merged into anterior margin at basal 3 / 5 tegmen length. Costal area widest near basal cell; postcostal area much wider than costal area. Hypocostal carina sigmoid, merged into stem R + M + CuA, hyposubcostal carina straight, close to stem R + M + CuA gradually; costal fracture curved apically, originating from stem R, stretched cross vein Pc + CP vertically. Basal cell closed, nearly triangle in shape. Vein R slightly curved, first forked into veins RA and RP at apical 1 / 4 of tegmen length; vein RA shorter than vein RP in length; vein RP curved posteriorly. Stem M + CuA strong and short, bifurcated first near basal 1 / 3 of tegmen length. Vein M curved anteriorly first, extending straight on middle membrane, then strongly bent towards vein CuA before reaching level of stem R forking. Vein M first forked into veins M 1 + 2 and M 3 + 4 at apical 1 / 5 tegmen length; veins M 1, M 2 and M 3 + 4 single; crossvein r - m connected veins RP and M 1 + 2; crossvein m - cu connected to evenly curved M 3 + 4 and CuA 1. Vein CuA single and straight, extending in direction of stem M + CuA; vein CuA divided into veinlets CuA 1 and CuA 2 near same level of vein R fork; vein CuA 1 curved strongly towards posterior margin, vein CuA 2 shorter than vein CuA 1, merely just extending beyond clavus apex. Vein CuP single, slightly curved basally before leaving basal cell, then extending straight towards clavus apex after connecting with long crossvein cua - cup. Clavus large and convex, with anal angle about 120 ˚; vein Pcu single, curved posteriorly, forming a “ Y ” fork with vein A 1. Vein A 2 close to A 1, parallel with postclaval margin and merged before end level of vein CuP. Small, irregular, dark-colored patterns shown on tegmen.