The four existing species of the ascophoran bryozoan Pentapora Fisher, 1807 are revised, and two new fossil species are introduced Pentapora lacryma sp. nov. from the Pliocene Coralhne Crag Formation of Suffolk, and Pentapora dlipeus sp. nov. from the Pliocene of Emilia, Italy. The Arctic species Pentapora boreale Kuklinski & Hayward possesses a lyrula, does not belong in Pentapora, and is a junior synonym of Raymondcia rigida (Lorenz) The morphology of the autozooids is relatively uniform within the genus, and the main distinguishing characters are those of the ovicells and, particularly, the giant avicularia that are developed sporadically in all species apart from Pentapora foliacea, popularly known as `Ross coral'. A phylogenetic analysis based on skeletal characters returned a single shortest tree in which the three species of Pentapora from the North Atlantic (P foliacea, Pentapora pertusa, and P lacryma sp. nov.) form a dade crownward of the three basal species from the Mediterranean (Pentapora ottomulleriana, Pentapora fascialis, and P clipeus sp. nov.). (C) 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160, 17-39.