Bathyteuthoidea

These are small mesopelagic to bathypelagic squids.  They have suckers on the buccal membrane; no carpal locking apparatus on tentacles; branchial canals in gills.
Arms:  Suckers in four or more series at some point on arms I-III. Suckers without circularis muscles. Tentacles: Club not divided into manus and dactylus. Carpal-locking apparatus absent. Club suckers with more than seven irregular series. Suckers without circularis muscles. Buccal crown: Buccal supports bear small suckers. Head: Has tentacle pockets. Mantle: The locking-apparatus reaches anterior mantle edge. Fins:  Have posterior lobes. Gladius: Has a spoon-shaped conus. Viscera: Gills have branchial canals and oviducts are paired. Comments: Buccal connectives attach to the ventral borders of Arms IV on the Chtenopterygidae and to the dorsal borders in the Bathyteuthidae.  Suckers on the buccal supports are found in members of only four families (Bathyteuthidae, Chtenopterygidae, Loliginidae, Sepiidae).  The suckers look much like the arms suckers but smaller.
Bathyteuthidae Pfeffer 1900 Chtenopterygidae Grimpe 1922
Bathyteuthida
The two genera that represent these families (Bathyteuthis, Cthenopteryx) were, at one time, placed within the same family (e.g., Naef, 1921) because they share a number of similar features. They especially show strong similarities in the structure of the tentacular clubs, the sucker arrangement on the arms and the morphology of their gladii. Roper (1969) considered them to belong to separate families and emphasized the differences in the attachment of the buccal crown to arms IV. Others (e.g., Clarke, 1988) have considered them to be distantly related. Their close relationship to one another, however, has been confirmed by a molecular study (Carlini, 1998).

Clarke, M. R. (1988). Evolution of recent cephalopods -- A brief review. P. 331-313. In: Clarke, M. R. and E. R. Trueman (Eds.). The Mollusca. Vol. 12. Paleontology and Neontology of Cephalopods. Academic Press, New York. 355pp.

Carlini, D. B. The phylogeny of coleoid cephalopods inferred from molecular evolutionary analyses of the cytochrome oxidase I, muscle actin, and cytoplasmic actin genes. Ph.D. diss. Coll. William and Mary, 273 pp.

Naef, A. (1921/23). Cephalopoda. Fauna und Flora des Golfes von Neapel. Monograph, no. 35. English translation: A. Mercado (1972). Israel Program for Scientific Translations Ltd., Jerusalem, Israel. 863pp., IPST Cat. No. 5110/1,2.

Nautilus Live Ocean Exploration Trust. 2012.  Image of Chtenoptertyx sicula.

Roper, C.F.E. 1969. Systematics and zoogeography of the worldwide bathypelagic squid Bathyteuthis (Cephalopoda: Oegopsida). Bulletin of the United States National Museum, 291:1-210.