Examination of a collection of Chaetopteridae (Annelida: Polychaeta) from the Iranian coast of the Persian Gulf led to the erection of a new species of Spiochaetopterus: S. creoceanae sp. nov. This is a small, oculate Spiochaetopterus with a single specialised, enlarged cutting seta on each A4 parapodium; this seta is roughly heart-shaped (cordate) in end view and with the outer lobe of the oblique section more developed than the inner one. The new species is mainly characterised by the presence of 10 segments in the anterior region, while all other species described to date have only 9. The description of this new species of Spiochaetopterus is a contribution to the growing evidence supporting the hypothesis that Spiochaetopterus costarum, formerly considered to be a cosmopolitan species, has in fact been used for several distinct species. In addition, the habitat preferences of the new species are also discussed.Se describe una especie nueva de Chaetopteridae en el Golfo Pérsico. Spiochaetopterus creoceanae, se trata de una especie pequeña, provista de ojos u con una única seda en cada parápodo A4. La característica principal de la nueva especie es la presencia de 10 segmentos en la región anterior mientras que las demás especies tienen 9. Asimismo se discuten características del hábitat de la nueva especie.Peer reviewed