Opisthoteuthis dongshaensis Chung-Cheng Lu, 2010

Introduction

The cephalopod fauna of the South China Sea is poorly understood in spite of the apparent rich number of species (ca. 120 species) and their economic importance (over 500,000 tons annually) (Norman and Lu, 2000). O. dongshaensis is the only positively known Opisthoteuthis from this region since a previously record of O. depressa (Dong, 1988) was a female, and therefore, possibly belongs to this species. O. dongshaensis is a small-bodied species with moderate compression of the bell-shaped cephalopodal mass. The description is based on the examination of 23 specimens.

Brief diagnosis:

A. Opisthoteuthis with ...

• Greatly enlarged suckers in the distal field of the male only on arms III and IV.
  

Characteristics

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

Figure. Opisthoteuthis dongshaensis, paratype. Left - Dorsal view. Right - Ventral view.  Photographs from Lu (2010).

1. Head
   1. Head wider than mantle; eyes large, laterally orientated; areolar spots absent.
2. Fins
   1. Relatively long (up to 173% of ML), paddle-shaped; base deeply embedded in gelatinous tissue of mantle. Anterior and posterior margins of fins weakly convex; basal constriction poorly developed.
      
      

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

      
      

      Figure. O. dongshaensis, holotype, mature male, 38 mm ML, 221 mm TL. Left - Dorsal view. Middle - Ventral view. Right - Oral view.  Scale bar = 50 mm.  Photographs from Lu (2010).

3. Funnel and mantle
   1. Mantle attached to arm IV bases at level of 6th sucker.
      
   2. Funnel organ unknown.
   3. Median mantle adductor short and thin.
      
4. Arms
   1. Arm formula variable, no consistent pattern.
   2. Arms long (longest 349-541% of ML.
   3. Web formula variable, no consistent pattern.
   4. Web nodules absent.
   5. Web thick and gelatinous; web sectors vary from 20% to 85% of longest arm.
   6. First cirrus between suckers 3 and 4 or 4 and 5 on all arms.
   7. Sucker size sexually dimorphic, distinctly enlarged in males.
      
   8. Proximal sucker field of mature males with enlarged suckers; distal sucker field only on arms III and IV and bearing 3 or 4 enlarged to greatly enlarged suckers.
      
      

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

      
      

      Figure. Oral views of O. dongshaensis. Top - Photographs. Bottom - Drawings. Left - Male, 35 mm ML. Right - Female, 34 mm ML.  Photographs and drawings from Lu (2010).

       

5. Viscera:Digestive tract
   
   

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

   
   

   Figure. Digestive tract of O. dongshaensis, male, 45 mm Head Width. Top - Ventral view. Bottom - Dorsal view. Photograph from Lu (2010).
   

    

   1. xx
      

6. Optic nerve bundles
   

   

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

   
   

   Figure. O. dongshaensis, male 46 mm head with showing the optic lobe (ol), white body (wb) and optic nerve bundles (on). Left - Broad view. Scale = 10 mm. Right - Close view. Scale = 5 mm. Photographs from Lu (2010).
   

xxx

7. Shell
   1. xx
      
      

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

      
      

      Figure. O. dongshaensis, various views of the shell, male, 31 mm ML, 227 mm TL.  Photographs from Lu (2010).

       

Distribution

References

Lu, Chung-Cheng. 2010. A new species of Opisthoteuthis, O. dongshaensis sp. nov., from the South China Sea (Octopoda: Cirrata: Opsithoteuthidae). Zoological Studies, 49 (3): 405-420.