A new species of the rhynchocinetid genus Cinetorhynchus, C. gabonensis sp. n. from the Atlantic waters of Gabon, is described based on morphological and molecular comparisons and its distinctive colour pattern. This is the second known species of the genus in the eastern Atlantic, and the third species in the Atlantic as the whole. The new species is more closely related to the western Atlantic C. manningi, both having quadrispinose ambulatory dactyli (i.e. with unguis + 3 ventral spinules), but differs from the latter by the presence of an arthrobranch on the three anterior pereiopods (vs only on the first pereiopod in C. manningi). The branchial formula of the new species is consistent with most of the Indo-West Pacific congeners, and with the amphi-Atlantic C. rigens; the latter possessing trispinose ambulatory dactyli. Other distinctions of the new species from its congeners are in the carpal and meral spinulation of the ambulatory legs, and in the posterolateral and posteroventral armament of pleomeres IV and V. Cinetorhynchus gabonensis sp. n. differs from both known Atlantic congeners also by a specific colour pattern which is dense deep-red mottled with a pair of small white spots delineated by deep-red broad rings on the top of the third pleomere.