Mongoloniscus polyacanthum sp. nov., holotype A cephalon and pereonite 1 in dorsal view B pleonites, telson, and uropod in dorsal view C second antenna D pereopod 1 E pereopod 6 F pereopod 7 G pleopod 1 H pleopod 2 I–K pleopods 3–5 exopods. The abrupt tip of pleopod 2 endopod are indicated as dotted lines. Scale bars: 1 mm (A–F); 0.5 mm (G–K).