Forty two Chlorophyta and nine Heterokontophyta (Phaeophyceae) species of benthic marine algae were identified from collections made at the deep (> 27 m) fore-reef at Lee Stocking Island, Bahamas. Ten of these species represent first reports from the Bahamas Archipelago and the report of Pedobesia simplex (Meneghini ex Kützing) M.J.Wynne & F.Leliaert is probably the first authentic record from the western Atlantic. Collected at depths of 61 m, Avrainvillea cyathiformis sp. nov. is described herein. The new species attains a height of only 4.0 cm and has nearly cylindrical inner medullary filaments which measure to 20 µm in diameter. The filaments decrease in diameter, to 8 µm, at their distal ends and are tortuous. Avrainvillea cyathiformis differs from all other species of the genus in possessing cyathiform blades.