A new species of Callionymidae, Pseudocalliurichthys ikedai, is described based on a male and a female specimens collected from Iriomote Island, Ryukyu Islands, Japan. The species is unique among congeners in possessing a pair of supraorbirtal cirri, seven soft rays in the second dorsal fin, six soft rays in the anal fin, seven abdominal and 13 caudal vertebrae, and the preoperculo-mandibular canal with four pores below the preopercular spine. A very small dragonet was collected from the riverine estuary of Iriomote Island, Ryukyu Islands. This specimen, a female, was recognized as a species of Pseudocalliurichthys because it possessed a straight preopercular spine with inward processes, many bony tubercles on occipital region, the postocular commissure not connecting with preoperculomandibular canal, and no transverse lateral-line canal commissure