Eurystylus Stal 1871

Key to the Eurystylus species in Vietnam 1. Dorsum mostly brown................................................................................. 2 – Dorsum entirely fuscous; thorax with yellowish stripes laterally; hypophysis of left paramere broad and rounded, posterior margin convex; endosoma with three distinct sclerites (Figs 1A–E, 2A–E)........................ E. yasunagai sp. nov. 2. Pronotum with a pair of noticeable circular dark spot......................................................... 3 – Pronotum with a pair of elongate dark spot, sometimes indistinct................................................ 4 3. Scutellum partly pale and dark brown, with longitudinal pale stripe medially (Fig. 1F).................... E. burmanicus – Scutellum mostly dark brown, with pale spots at each apex (Fig. 1G)................................ E. coelestialium 4. Third antennal segment entirely dark brown; hypophysis of left paramere broad and rounded, posterior margin convex; right paramere almost straight; primary lobal sclerite curved (Figs 1H, 2F–H).................................. E. ryukyus – Third antennal segment mostly dark brown with pale base; hypophysis of left paramere broad and angled, posterior margin concave, truncated; right paramere twisted; primary lobal sclerite straight (Figs 1I, 2I–L)..................... E. sauteri