Cycloteuthids are mesopelagic squids of moderate size, the largest reaches about 60 cm ML, with a cosmopolitan distribution in tropical and subtropical waters (Nesis, 1982). In Cycloteuthis the mantle and fins are drawn-out into a slender tail. A tail is lacking in Discoteuthis and the large, oval (disc-like) combined fins extend virtually the full length of the mantle. Very little is known about the biology of any species in the family.
An oegopsid ...
An oegopsid ...
This family is represented by seven species within two genera
Cycloteuthis Joubin, 1919:1.
CURRENT SYSTEMATIC STATUS. -- Valid genus [fide Young and Roper (1969:2)
TYPE SPECIES. -- Cycloteuthis sirventi Joubin, 1919 by monotypy
Discoteuthis Young and Roper, 1969:5.
CURRENT SYSTEMATIC STATUS. -- Valid genus [fide Nesis (1987:240)]
TYPE SPECIES. -- Discoteuthis discus Young and Roper, 1969 by original designation
Cycloteuthis akimushkini Filippova, 1968:119, figs 1-2.
CURRENT SYSTEMATIC STATUS. -- Valid species [fide Nesis (1987:240)]
TYPE REPOSITORY. -- ZMMGU Holotype
TYPE LOCALITY. -- Indian Ocean (9∞57'S, 91∞31'E)
Discoteuthis discus Young and Roper, 1969:5, pls 3-4, 7-9.
CURRENT SYSTEMATIC STATUS. -- Valid species [fide Nesis (1987:240)]
TYPE REPOSITORY. -- NMNH Holotype 576214 [fide Roper and Sweeney (1978:6)]
TYPE LOCALITY. -- 03∞50'N, 02∞37'W (Atlantic Ocean)
Discoteuthis laciniosa Young and Roper, 1969:9, pls 5-9.
CURRENT SYSTEMATIC STATUS. -- Valid species [fide Nesis (1987:241)]
TYPE REPOSITORY. -- NMNH Holotype 576215 [fide Roper and Sweeney (1978:8)]
TYPE LOCALITY. -- 33∞04'N, 64∞37'W (Atlantic Ocean)
Cycloteuthis sirventi Joubin, 1919:1, figs 1-2.
CURRENT SYSTEMATIC STATUS. -- Valid species [fide Young and Roper (1969:2)
TYPE REPOSITORY. -- MOM Holotype [station 3213] [fide Belloc (150:5)]
TYPE LOCALITY. -- 30∞45'40"N, 25∞47'W, off Madeira
The features that unites these two genera is the similar triangular shape of the funnel locking-apparatus and the position of the mantle component. Other than these unusual features, there is little morphological evidence for their close relationship. Molecular evidence (Carlini, 1998; Lindgren, 2010) supports their close relationship. A more recent study, however, found the two genera only distantly related (Lindgren, 2012).
The genera are easily separated by body and fin shape (see title illustrations). In addition the presence of a large visceral photophore only in Cycloteuthis allows genera to be separated when badly damaged.