A new species of rhacophorid frog of the genus Chiromantis is described from Phnom Samkos in the northwestern section of the Cardamom Mountains, Cambodia on the basis of having the following unique characteristics: green blood; turquoise bones; a thick, white line running from below the midsection of the eye onto the upper lip to the shoulder; and fingers III and IV being more than one-quarter webbed. It is further distinguished from its congeners by a unique combination of additional morphological and color pattern characteristics. This new species is the eighth potential endemic known from the Cardamom Mountains and underscores the need for continued field work in this remote section of Indochina.