(Claus, 1879)
Length 12-16 mm. Head 2.5 times as high as long, 4 times as wide as long (Platyscelus armatus 1). All pereonites and pleonites with convex dorsal surface (animal slightly accordion-like). Coxae V and VI larger than others, CX V more or less pointed, projecting laterally in adults (projection rarely weak or very weak). ART 5 of P I, not including distal process, longer than wide (Platyscelus armatus 2); distal process broad, top corner about 60-80°; margins of this process and posterior margin of ART 6 finely serrate, anterior margin of ART 6 smooth. ART 5-6 in P II as in P I, but distal process of ART 5 moderately stronger. ART 2 of P VII broadened, with concave anterior, convex posterior margins, with two rudimentary distal ART (Platyscelus armatus 3).