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Containing group: Todarodes

Introduction

Todarodes pusilllus is a dwarf ommastrephid that appears to have a maximum size of less than 80 mm ML. It is generally considered to be a subspecies of T. pacificus. Distinct differences exist between the two forms and, although we have no new information, we consider them to represent separate species. Clearly molecular genetic analysis is needed to clarify their relationships especially in light of the finding by Dunning (1988) that some specimens from Hong Kong, Taiwan and the Philippines were intermediate in some characters between the Japanese form (his T. pacificus pacificus) and the Australian form (his T. pacificus pusillus).

Characteristics

1. Arms (Dunning, 1998)
   
   1. Right arm IV hectocotylized; hectocotylized region is 45-57% of arm length; 11-13 normal suckers present proximally; ventral trabeculae broadened and joined to form low serrated fan with about 20 pairs of trabeculae.
      
      

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      Figure. Hectocotylus of T. pusillus, 68 mm ML. Top - Dorsal view. Bottom - Ventral view. Photographs from Dunning (1988).
      

   2. Arms subequal and large; longest (arm II or III) slightly less than half ML.
   3. Largest arm suckers with 9-11 sharp subequal teeth on distal 2/3 of ring.
      
      

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      Todarodes pusillus. © 1988 Memoirs of the Museum of Victoria Dunning, M. 1988. Todarodes pacificus pusillus New Subspecies (Cephalopoda:Ommastrephidae) from Northern Australia. Memoirs of the Museum of Victoria,49(1):149-157.

   4. Protective membranes of uniform  height, not higher than arm suckers.
      
      
2. Tentacles
   1. Manus with 6-8 quadraserial sucker rows (Dunning, 1988, 1998).
   2. Medial manus sucker rings with 16-18 moderately large, subconical teeth interspersed with low plates; about 2.5 times marginal suckers in diameter (Dunning, 1988).
      
      

      Click on an image to view larger version & data in a new window

      
      

      

      Click on an image to view larger version & data in a new window

      
      

      Todarodes pusillus. © 1988 Memoirs of the Museum of Victoria Dunning, M. 1988. Todarodes pacificus pusillus New Subspecies (Cephalopoda:Ommastrephidae) from Northern Australia. Memoirs of the Museum of Victoria,49(1):149-157.

   3. Carpal suckers arranged as 2,2,1 (right club) or 1, 2, 1 (left club) with dentition similar to largest arm suckers; locking apparatus absent (Dunning, 1988).
   4. Protective membranes extend to carpal region; height never exceeds sucker height; supports weak (Dunning, 1988).
      
      
3. Head (Dunning, 1988)
   1. Funnel component of locking-apparatus inverted T-shaped.
   2. Funnel groove with foveola, no side pockets.
      
      
4. Fins
   1. Fin length 25-31% of ML (Dunning and Wormuth, 1998).

Discussion of Phylogenetic Relationships

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Life History

Females mature at 60 mm ML, males mature at 50 mm ML (Dunning, 1988).

Distribution

Type locality: Timor Sea, northeast Indian Ocean at 13°48'S, 124°19'E, bottom depth 102 m.

Known distribution from off western Australia between 8°53'S (Timor Sea) and 19°31'S and from off eastern Australia between 17°16'S and 27°S. All specimens taken in bottom trawls on bottoms of 78-357 m. 54 specimens were taken in a single trawl suggesting a schooling habit. (Information from Dunning and Wormuth, 1998).

References

Dunning, M. C. 1998. Ommastrephidae. In: Carpenter, K. E., Niem, V. H. (eds.). FAO species identification guide for fishery purposes. The living marine resources of the Western Central Pacific. Vol. 2. Cephalopods, crustaceans, holothurians and sharks. FAO, Rome. p. 687-1396.

Dunning, M. C. and J. H. Wormuth. 1998. The ommastrephid squid genus Todarodes: A review of systematics, distribution, and biology (Cephalopoda: Teuthoidea). . Smithsonian Contributions to Zoology, No. 586: 385-391.