The reduviine assassin bug, Tiarodes miyamotoi Ishikawa, Cai and Tomokuni, 2005 (Hemiptera: Heteroptera: Reduviidae: Reduviinae), has so far been known only from the Yaeyama Islands of Japan and no major intraspecific variation has been reported in this species.

This is the first record of this species from Okinawa-honto Island as the northernmost locality. Furthermore, an apparently discontinuous intraspecific variation in coloration has been confirmed between populations from the Yaeyama and Okinawa-honto Islands; this variation has been reported for the first time in the genus Tiarodes Burmeister, 1835, which comprises approximately 90 species.