﻿AbstractThe blattid cockroachPeriplanetaarabica(Bey-Bienko, 1938) has been poorly understood since its original description. In this study, male and female (including nymph) ofP.arabicaare paired using DNA barcoding, and their morphological characters (including both external characteristics and genitalia) are described. A detailed comparative morphological study of this species and the closely relatedPeriplanetaamericana(Linnaeus, 1758) andPeriplanetalateralisWalker, 1868 was carried out to explore phylogenetically relevant characters.