Middle Eocene deep-sea sediment sequences cored at Ocean Drilling Program Site 1260 (Leg 207; equatorial Atlantic Ocean), yielded diverse and abundant radiolarian faunas which are conducive to biostratigraphic and palaeoceanographic researchs, as well as to the study of radiolarian diversity dynamics during this epoch of dramatic climate changes. However, many species present in these sediments still have not been formally described and are therefore neglected in most biodiversity surveys. In an effort to improve the taxonomic resolution of middle Eocene radiolaria, 15 new species of nassellarian are described and illustrated. The species are: Cymaetron ? dilatatus n. sp., Eucyrtidium levisaltatrix n. sp. (Eucyrtidiidae), Siphocampe pollen n. sp., Spirocyrtis ? renaudiei n. sp. (Artostrobiidae), Pterocyrtidium eep n. sp. (Rhopalosyringiidae), Petalospyris cometa n. sp., Petalospyris castanea n. sp. (Cephalospyrididae), Velicucullus armatus n. sp. (Theophormididae), Lychnocanium nimrodi n. sp. (Lithochytrididae), Aphetocyrtis zamenhofi n. sp., Aphetocyrtis ? columboi n. sp., Aphetocyrtis ? spheniscus n. sp. (Lophocyrtiidae), Albatrossidium regis n. sp., Albatrossidium annikasanfilippoae n. sp. and Phormocyrtis lazari n. sp. (Pterocorythidae). Stratigraphic range data are provided for each new species, as well as the orbitally tuned ages for their first and last occurrences. In addition to these new species, we also illustrated and documented the stratigraphic distribution of three species described in early radiolarian studies and rarely reported since.