REDESCRIPTION OF THE DEEP-SEA CIRRATE OCTOPOD CIRROTEUTHIS-MAGNA HOYLE, 1885, AND CONSIDERATIONS ON THE GENUS CIRROTEUTHIS (MOLLUSCA, CEPHALOPODA)

The deep-living octopod Cirroteuthis magna Hoyle, 1885 is redescribed, based on the only three specimens known of the species: a mature fema le (holotype) captured in the south Indian Ocean between Prince Edward and Crozet islands at 2557 m and two specimens, one submature female and one mature male, recently captured in the central Atlantic at 1300 and 3351 m depth, respectively. Video images from the capture of the latter specimen were recorded. This species is characterized by its ve ry great size (to 1300 mm TL), making it the largest known cirrate oct opod; butterfly-like shell with open wings; very voluminous eyes with large lenses; arm length 73-79% of the total length; primary web inser ted at different levels on the dorsal and ventral ends of the dorso- a nd ventrolateral arms on both sides, and at the same lever on both end s of the dorsal and ventral arms; each arm is independent of the prima ry web, and is connected with it by a single vertical membrane or inte rmediate web that is attached along the dorsum of the arm; absence of nodule at the fusion point of both webs. Very large cirri, the first c irri commencing between the 4th and 5th suckers, with three types of s uckers on all the arms; cylindro-conical form and those with the aceta bulum highly deformable on the first 2/3 of arms and barrel-like on th e rest of the arm; absence of particularly enlarged suckers. C. magna is compared with C. muelleri and other related species. Sperm sacs and spermatozoids from C. magna and C. muelleri are described and compare d. The Cirroteuthis ge nus is reviewed and a diagnosis is proposed. Th is study confirms that the members of the Cirroteuthidae family show s everal unusual features of great interest.