We report the first records of the new species Isodictya filiformis (Demospongiae, Poecilosclerida, Isodictyidae) from the Peter I Island, Low Island and Deception Island (Antarctic), between 97 and 210 m in depth. We add dataset about the species identified by Burton, in 1934 as Isodictya delicata var. megachela, from Seymour Island (Antarctic).

This research was conducted in the frame of the projects:ECOQUIM (Ecología química en el bentos antártico) (Chemical ecology in the Antarctic benthos) BENTART (Benthos antártico) http://www.bentart.es/ACTIQUIM (Actividad ecológica de productos naturales marinos de organismos bentónicos antárticos: Experimentos de ecología química in situ) (Natural marine products in Antarctic ecosystems)