Cycloteuthis  Cycloteuthis is a genus of squid in the family Cycloteuthidae. It is distinguished from the genus "Discoteuthis" by the presence of a tail on the mantle. The species "C. akimushkini" is currently considered a junior synonym of "C. sirventi", however this is inconclusive and the World Register of Marine Species has "C. akimushkini" as a valid species. The genus contains bioluminescent species.