First record of a cirrate octopus (Cephalopoda: Cirroteuthidae) in the Argentine Basin (Uruguay)

We report live observations of Cirrothauma cf. murrayi, the unique ‘blind cirrate octopus’ at a depth of 3,122 m depth during a SuBastian dive aboard RV ‘Falkor (too)’ in the Economic Exclusive Zone of Uruguay. The observed specimen exhibited an elongated body shape, distinct from a compressed form, with a gelatinous and fragile structure. Notable features include reduced or degenerate eyes, lightly pigmented skin, a deep web with a secondary web, long conspicuous cirri, elongate stalks with minute suckers, and large, wide fins that exceed the width of the head. The oceanographic setting indicates the presence of a mixing layer between the North Atlantic Deep Water (NADW) and the Lower Circumpolar Deep Water (LCDW). This record enhances the limited knowledge of Cirroteuthidae distribution in this region, with previous records restricted to Brazil and the Southern Ocean (South Sandwich Islands), being the first one for the Argentine Basin.