A new genus with a new species of poecilostomatoid copepod, Polyankylis orientalis, is described based on a pair of specimens collected from a tide pool on muddy shore in Korea. It represents a new family of the lichomolgoid complex with the following distinguishing characters: (1) 6-segmented antennule (resulted from the fusion of the third and fourth segments) with additional aesthetascs in male, (2) hook on mediodistal corner of antennal coxobasis (first segment), (3) proximal and distal scales on the outer margin of mandible present, (4) main axis of mandibular gnathobase short and lacking notches at the base of mandibular lash, and (5) inner margin of mandibular lash with denticulate processes. Additionally, maxillar syncoxa carries a large, pointed process on ventral surface, legs 1-4 do not show sexua1 dimorphism, and leg 4 is uniramous with 1-segmented exopod. A detailed discussion is given of its affinities with the ten existing families of the lichomolgoid complex.