Opisthoteuthis robsoni: Description Continued

1. Suckers
   1. Suckers muscular with simple aperature (see drawing on right).
   

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   Figure. Sucker of O. robsoni, longitudinal section. Drawing from O'Shea (1999).

2. Eyes
   1. Large
3. Funnel
   1. Funnel organ V-shaped.
4. Fins
   1. With anterior fin lobes??
      
      
5. Gills
   1. 6-8 primary lamellae.
   2. Base of lamellae 3 and 4 with common afferent vessel.
      
      
6. Optic lobe and nerves
   1. Optic lobe kidney shaped.
   2. 2-3 optic-nerve bundles penetrate white body on left side and 3-4 on right side. (The white bodies are dark brown to purple in color.)
   

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   Figure. Optic lobe complex (optic lobe, optic stalks and white body) of O. robsoni, male, 31 mm ML. Left - Left side. Right - Right side.  Drawings from O'Shea (1999).

7. Digestive system
   1. Radula absent.
   2. Salivary glands absent.
   3. Crop present as expanded esophagus.
   4. Stomach large without external demarcation.
   5. Caecum poorly developed, without spiral coiling.
   6. Intestine about 1.5 times esophagus lengh.
   7. Digestive gland unilobular.
   

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   Figure. Digestive system of O. robsoni, male, 62 mm ML. Drawing from O'Shea (1999).

8. Beaks
   1. Upper jaw with single, broad-based tooth and strong lateral-wall fold.
   2. Lower beak with long lateral wings (98% of beak length) and two weak folds.
   

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   Figure. Beaks of O. robsoni, male, 62 mm ML. Left - Upper beak. Right - Lower beak. Drawings from O'Shea (1999).

9. Male reproductive system
   1. Complex of accessory glands 1-3 greater in size than seminal vesicle complex.
   2. Accessory glands 2 and 3 dominate complex.
   3. Penis well developed, tubular.
   

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   Figure. Male reproductive system of O. robsoni, 62 mm ML. Drawing from O'Shea (1999).

10. Shell
    1. Shell not solid ("vacuolate").
    2. Saddle with single deep excavation (outer surface convex, inner surface concav).
    3. Fin insertion points marked by 2 well-developed shoulders.
    4. Wings diverge from saddle at 45° angle; taper to acute point.
    

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    Figure. Shell of O. robsoni, male, 62 mm ML; lateral view (left), dorsal (?) view (right). Photographs from O'Shea (1999).

11. Pigmentation
    1. Areolar spots on dorsal surfaces of mantle, head and arm bases; 7 spots on head and each arm I, 6 spots on head and each arm II, 4 spots on each arm III and 3 spots on each arm IV.
    2. Dorsal and ventral surfaces maroon.
    3. Margins of eyes, outer margins of fins and cirri, off-white.
    4. Oral surfaces of arms and web, deep maroon, nearly black; suckers and sucker aperatures off-white to pale yellow.
       
       
12. Measurements
    1. Measurements and counts can be found here.

Comments

The above description is from O'Shea (1999).

References

O'Shea, Steve. 1999. The Marine Fauna of New Zealand: Octopoda (Mollusca: Cephalopoda). NIWA Biodiversity Memoir 112: 280pp.