Stoloteuthis Verrill, 1881

Introduction

Species of Stoloteuthis are heteroteuthins with arms one forming the primary (subjective category) hectocotylization (unknown in S. weberi) and a tentacular organ but exhibit unusual variability in the dorsal fusion of the head and mantle and the size of the ventral mantle shield. The genus as constituted here probably does not form a natural group due to the inclusion of the poorly known S. weberi and the distinctive Stoloteuthis sp. A. However until both of these two species are better known and we are confident that there are not too many surprises left in the Heteroteuthinae, we prefer not to name a new genus.

Brief diagnosis:

A heteroteuthin with ...

• enlarged suckers on arms II of males (except S. sp. A).
• arms I very broad (hectocotylized) (not apparent in S. weberi).
  

Characteristics

1. Arms
   1. Arm suckers relatively larger in males but no arm asymmetry present.
   2. Arms II, in males, with one to several greatly enlarged (encept in S. sp. A).
   3. Arms I, in males, very broad (not apparent in S. weberi).
      
   

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   Figure. Oral view of brachial crown (minus tentacles) of S. maoria, mature male, off S.E. New Zealand (44°02'S, 178°08'W), otter trawl at 230-421 m. Drawing by A. Hart.

   4. Arm tips in females not modified (except S. sp. A, unknown in S. weberi).
   5. Suckers of arms IV in females in two identical series (unknown in S. weberi).
      
      
2. Tentacles
   
   1. Tentacle organ of club proximal to or barely overlapping sucker-bearing portion of club (unknown in S. weberi).
      
      
3. Funnel
   1. Funnel/mantle locking-apparatus with straight, simple groove in funnel component or groove with anterior angular pit (unknown in S. weberi).
      
      
4. Mantle
   1. Mantle broadly or narrowly fused to head dorsally, or free.
   2. Ventral mantle does not extend beyond middle of eyes.
      
      
5. Fins
   1. Fin margins rounded posteriorly (except probably in S. maoria).

Comments

S. weberi, which is known only from the type specimen, was formerly placed in Heteroteuthis. This species lacks a dorsal head-mantle fusion, a feature that distinguishes it from all other Stoloteuthis except Stoloteuthis sp. A but in the arrangement of arm suckers, it resembles Stoloteuthis species. S. maoria was formerly placed in Iridoteuthis. Harman and Seki (1990) re-examined S. maoria and found that it was similar to Iridoteuthis iris in its broad head-mantle fusion, middorsal mantle buldge and posteriorly pointed fins. We place S. maoria in Stoloteuthis on the basis of the arm modifications in mature members of both sexes which are similar to S. leucoptera. Most of the generic-level characters, however, are presently unknown in S. weberi. Stoloteuthis sp. A, like S. weberi, was originally placed in Heteroteuthis. However the hectocotylization is very unlike that of Heteroteuthis but resembles that of Stoloteuthis.

Comparison of species 

Life History

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Figure. Dorsal and ventral views of young S. leucoptera, 9.8 mm ML. Drawings from Vecchione, et al. (2001).

Distribution

S. leucoptera is known from off the eastern United States and the eastern Atlantic including the Mediterranean Sea; S. weberi from Indonesia (7.6°S, 117.5°E) and S. maoria from off New Zealand. Unidentified species of Stoloteuthis have been reported from near the Kerguelens, Prince Edward Islands (southern Indian Ocean), Discovery Bank (southeast Atlantic (Nesis, 1982/87) and east of Tasmania (Villanueva and Sánchez, 1993).

References

Cairns, S. D. 1976. Biological results of the University of Miami deep-sea expeditions. 118. Cephalopods collected in the Straits of Florida by the R/V Gerda. Bull. Mar. Sci. 26: 233-272.

Nesis, K. N. 1982/87. Abridged key 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.

Orsi Relini, L. and D. Massi. 1991. The butterfly squid Stoloteuthis leucoptera in the Mediterranean. J. Mar. Biol. Ass. U. K. 71: 47-51.

Vecchione, M., C. F. E. Roper and M. J. Sweeney. 1989. Marine flora and fauna of the eastern United States. Mollusca: Cephalopoda. NOAA Tech. Rep. NMFS 73: 23 pp.

Vecchione, M., C. F. E. Roper, M. J. Sweeney and C. C. Lu. 2001. Distribution, relative abundance and developmental morphology of paralarval cephalopods in the western North Atlantic Ocean. NOAA Tech Rep. NMFS 152.