Sepiolidae Leach 1817

Introduction

Sepiolids are small (ca. 1-10 cm ML), broad cephalopods with a rounded posterior mantle and ear-like fins. Species of the Rossinae and Sepiolinae are benthic while those of the Heteroteuthinae are pelagic. The most distinctive group is the Heteroteuthinae in which the ventral mantle margin extends beneath the head and the photophores are fused into a single large organ. All sepiolids, where known, lay large benthic eggs and the young hatch out at an advanced stage of development and their lenght may be one quarter of that of the adult female (Naef, 1921-23).

Diagnosis

A Sepiolida ...

• with funnel locking-apparatus with a single depression.

Characteristics

1. Arms
   1. One or both arms I hectocotylized; one arm II may also be modified.
      
      
2. Funnel
   1. Funnel locking-apparatus often with an elongate-oval groove but considerable variability may exist.
      
      
3. Mantle
   1. Dorsal margin fused to or free from head.
      
      
4. Shell
   1. Shell a thin or rudimentary gladius or absent.

Comments

The following table compares the three subfamilies.

Nomenclature

A list of all nominal genera and species in the Sepiolidae can be found here. The list includes the current status and type species of all genera, and the current status, type repository and type locality of all species and all pertinent references.

Discussion of Phylogenetic Relationships

We follow the classification of Naef (1921-3) in dividing the Sepiolidae into three subfamilies. We disagree, however, in his placement of Sepiolina in Sepiolinae. We place it in the Heteroteuthinae. As Naef (1921-23) recognized, characteristics of this genus place it right between the two subfamilies. Additional studies are needed to resolve the position of Sepiolina.

A cladistic analysis has not been made on this family but one is badly needed as much disagreement exists over classification. Clarke (1988) includes this family and the Idiosepiidae in the Order Sepiolida. Fioroni (1981) includes this family in the Order Sepioloidea and includes the Idiosepiidae as a subfamily of the Sepiolidae.

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.

Fioroni, P. 1981. Die Sonderstellund der Sepioliden, ein Vergleich der Ordnungen der rezenten Cephalopoden. Zool. Jahrb., 108: 178-228.

Lu, C. C., A. Guerra, F. Palumbo and W. C. Summers. 1992. Order Sepioidea Naef, 1916. In: Sweeney, M. J., C. F. E. Roper, K. M. Mangold, M. R. Clarke and S. V. Boletzky (eds.). "Larval" and juvenile cephalopods: a manual for their identification. Smithson. Contr. Zool. No. 513: 1-282.

Naef, A. 1921/23. Cephalopoda. Fauna e Flora del Golfo di Napoli. Monograph, no. 35. English translation: A. Mercado (1972). Israel Program for Scientific Translations Ltd., IPST Cat. No. 5110/1,2.

Nesis, K. N. 1982. Abridged dey to the cephalopod mollusks of the world's ocean. 385+ii pp. Light and Food Industry Publishing House, Moscow. (In Russian.). Translated into English by B. S. Levitov, ed. by L. A. Burgess (1987), Cephalopods of the world. T. F. H. Publications, Neptune City, NJ, 351pp.