The deep-sea bottom samples from the flat of Cap Vert, tropical Atlantic Ocean, collected during the EUMELI cruises, contain eight demoscolecid species, six of them belong to the subgenus Quadricoma. The dominant species Tricoma (Quadricoma) maxima is rediscribed including SEM information on the head region. A new species Tricoma (Quadricoma) magnafenestra sp. nov. is characterised by a relative long body with 44 main rings, an end ring with large pores or phasmata and spike-like spinneret, a broad head with truncated anterior end with labial rim, males with 55µm long spicules. Additional information is given on T. (Q.) loricata. The taxonomic status of T. (Q.) media is discussed; the species is considered as a species inquirenda
