Revision of the north-eastern Atlantic and Mediterranean species of the genera Herentia and Therenia (Bryozoa: Cheilostomata)

The cheilostome genera Herentia Gray and Therenia David and Pouyet, placed in the recently established family Escharinidae Tilbrook, were hitherto generally regarded as synonyms of Escharina Milne Edwards. Here we resurrect and define both genera, and revise their eastern Atlantic and Mediterranean species, which turn out to be species complexes. Besides presenting a re-description of the genotype of Herentia, H. hyndmanni (Johnston) from the British Isles, new species from Madeira (Herentia andreasi n. sp.) and the Adriatic Sea (Herentia majae n. sp.) are introduced. The ancestrula of H. hyndmanni, a kenozooid with an almost completely calcified, gymnocystal frontal shield, is here documented for the first time. For Therenia it can be shown that the type species T. porosa (Smitt) from Florida differs from the eastern Atlantic and Mediterranean congeners, all of which were hitherto referred to as this species. Consequently, three new species (Therenia cryptooecium n. sp. from Ghana, Therenia peristomata n. sp. from Madeira, and Therenia rosei n. sp. from the Mediterranean Sea) are described. Both genera show a Paleogene origin and distribution in the Tethyan and Atlantic regions, and persist today in tropical to warm-temperate zones of the Atlantic and Mediterranean Sea. Investigation of poorly studied, low- to mid-latitude regions are likely to yield more new species of Herentia and Therenia.