Bathyteuthoida Vecchione, Young and Sweeney, 2004

Introduction

Diagnosis

A decapodiform ...

• with suckers on the buccal membrane.
• without carpal locking-apparatus on tentacles.
• with branchial canals in gills.

Characteristics

1. Arms
   1. Suckers in four or more series at some point on arms I-III.
   2. Suckers without circularis muscles.
2. Tentacles
1. Club not divided into manus and dactylus.
2. Carpal locking-apparatus absent.
3. Club suckers in more than 7 irregular series.
4. Suckers without circularis muscles.
3. Buccal crown
   1. Buccal supports bear small suckers.
      image info

      Figure. Side view of buccal crown and oral views of arms II and III of Bathyteuthis berryi. Arrows point to suckers on the buccal supports. Photograph by R. Young.

4. Head
   1. Head with tentacle pockets.
5. Mantle
   1. Mantle locking-apparatus reaches anterior mantle edge.
6. Fins
   1. Fins with posterior lobes.
7. Shell
   1. Shell a gladius with conus present in Chtenopteryx but absent in Bathyteuthis.
8. Viscera
   1. Gills with branchial canals.
   2. Oviducts paired.
9. Eggs
   1. Egg masses unknown.

Comments

Buccal connectives attach to the ventral borders of Arms IV in the Chtenopterygidae and to the dorsal borders in the Bathyteuthididae. Suckers on the buccal supports are found in members of only four families (Bathyteuthidae, Chtenopterygidae, Loliginidae, Sepiidae). The suckers look much like the arm suckers but are much smaller.

Discussion of Phylogenetic Relationships

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).

The relationship of the Bathyteuthoida to other groups is uncertain as they share some characters with both the Oegopsida and the Myopsida.

References

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.

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.