We report the first record of the hydroid Bedotella armata (Pictet & Bedot, 1900) from a bathyal region of the Porcupine Seabight, southwest Ireland. Bedotella armata was thought to be endemic to the southern Lusitanian province and the Mediterranean.Yet specimens were common in box cores on and off living coral mounds formed by the scleractinian Lophelia pertusa. Irish colonies were slightly larger than those from the Strait of Gibraltar and the Bay of Biscay.We hypothesize that the association of B. armata with L. pertusa could explain morphological differences, as hydroids on reef structures may benefit from better feeding opportunities in enhanced flow conditions. We also hypothesize that post-glacial hydroid colonization of these mounds during the Holocene was partly due to species emigration from the warm saline Mediterranean Outflow Water (MOW) mass. Our findings support the hypothesis that MOW could play a significant role in determining the distribution and recent origins of mound fauna in the Porcupine Seabight.The current findings become the deepest, northernmost record of B. armata.