| Archaphanostoma agile (Jensen, 1878) | prior to 1975 | | | |
| Acmostomum dioicum Metschnikoff, 1865 | 1950 | | | uncommon. |
| Plagiostomum vittatum (Frey & Leuckart, 1847) | 1955 or earlier | | | |
| Provortex affinis (Jensen, 1878) | 1913 or earlier | littoral | | |
| Provortex balticus (Schultze, 1851) | 1893 or earlier | | | |
| Procerodes ulvae (Ørsted, 1843) | 1958 or earlier | | | Scarlett Point. |
| Oligocladus sanguinolentus (Quatrefage, 1845) | 1893 or earlier | | | |
| Caenoplana sanguinea Moseley, 1877 | 1988 or earlier | | | N. Ireland; Isles of Scilly, Isle of Man, and Dorset, England. |
| Macrostomum hystricinum Beklemischev, 1951 | 1953 or earlier | | | |
| Kontikia andersoni Jones, 1981 | 1988 or earlier | | | Isles of Scilly and Isle of Man, England. |