The female of Haplostomides hibernicus (Scott and Scott, 1895) is fully redescribed on the basis of a single specimen living in the compound ascidian Polyclinum aurantium Milne Edwards, which was obtained at Strangford Lough in the Irish Sea in 1995. This copepod was collected by the author, together with specimens of H. scotti Chatton and Harant, 1924, from the same ascidian. The redescription confirms that the specimen of H. hibernicus is comparable in morphology to the copepods that Scott and Scott (1895) described as (?)Enterocola hibernica from Valentia Island and that Chatton and Brément (1910) redescribed as Aplostoma hibernica from Roscoff. The result of this study indicates that H. scotti is synonymous with (?)E. beaumonti Scott and Scott, 1895, which was found together with (?)E. hibernica in an unidentified ascidian at Valentia Island.