Taonius borealis (Nesis, 1972)

Introduction

Taonius borealis, known only from the temperate and boreal North Pacific, reaches a maximum size of 50 cm ML (Nesis, 1972).

Brief diagnosis:

A Taonius with ...

• Largest club sucker with one primary hook-like tooth and about 6-8 secondary hook-like teeth. 
• Large club suckers of marginal series of manus not laterally compressed.

Characteristics

1. Arms
   1. Arms short, about 1/4 of ML.
   2. Largest arm sucker-rings with low, truncated closely-set teeth on distal half or all around.
   
   
   

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   figure. Large arm suckers of T. borealis. Left - Distal-oral view of whole sucker (sucker 11 of arm II, 240 mm ML). Middle - Oral view of inner ring of same sucker. Right - Oral view of whole sucker (arm III, about 300 mm ML). Photographs by R. Young.
2. Tentacles
   1. Largest two suckers of medial two series of club manus with one enlarged, hook-like tooth; 3-4 smaller secondary teeth present.
   2. Other enlarged suckers of medial series of club manus with two largest hook-like teeth more nearly equal in size; 6-8 (total) smaller secondary teeth present.
      
   3. Suckers of marginal series of manus circular (ie, not laterally compressed) with long, pointed teeth on distal and lateral margin of sucker ring.
   4. Tentacular stalk with two series of locking suckers on distal 2/3 to 3/4 of stalk. Distinct carpal cluster at base of manus with 6-7 smooth ringed suckers and matching knobs; knobs not always obvious.
   
   
   

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   Figure. Two views of the same tentacular club of T. borealis, 240 mm ML, off Southern California. Photograph by R. Young

   

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   Figure. Manus suckers from T. borealis, male, about 300 mm ML, central temperate North Pacific. Left three - Three views of the largest medial manus sucker. Right two - Two views of a large marginal manus sucker.
   

   

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   Figure. Sucker from medial series of club dactylus of T. borealis, immature female, about 350 mm ML. Left two - Two views of the intact sucker. Right - Same sucker outer ring removed. Photographs by R. Young.
   

3. Head
   1. Occipital folds absent.
      
   2. Beaks: Descriptions can be found here: Lower beak; upper beak.
      
      
4. Mantle
   1. Skin dermis adjacent to the muscular mantle with alveolate structure (in large males only?).
      
5. Fins
   1. Fins lanceolate, about twice as long as combined width; 1/3 of ML.
      

Comments

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Figure. Head and arms of T. borealis. Left - Ventral view. Right - Dorsal view. Note the orange photosensitive vesicles on the "brain" within the cephalic cartilage; the skin has been removed from this area. Photographs by Henk-Jan Hoving.

Life History

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Figure. Left - Ventral view of a young T. borealis. Right - Composite of three photographs of the same individual showing the shape of the eyes that appear to be in transition from an eliiptical to a tubular or to a hemispherical shape. © 2013 MBARI .

Behavior

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Figure. Two photographs of the same T. borealis showing eye orientation. Left - Anterior view with laterally oriented eyes. Right - Anterior-oblique view with anteriorly oriented eyes. Photographs © 2011 MBARI.

Distribution

References

Akimushkin, I.I. 1963. Cephalopods of the Seas of the U.S.S.R. Academy of Sciences of the U.S.S.R., Institute of Oceanology, Moscow, 235 pages. English translation: Israel Program for Scientific Translations, Jerusalem, 1965.

Nesis, K.N. 1972. A review of the squid genera Taonius and Belonella (Oegopsida, Cranchiidae). Zoologichesky Zhurnal, 51(3):341-350

Voss, N. A. 1980. A generic revision of the Cranchiidae (Cephalopoda; Oegopsida). Bull. Mar. Sci. 30: 365-412.