Choneteuthis tongaensis: Description continued

Characteristics

1. Arms
   1. Ridges present along aboral midline of arms I, III and IV but indistinct on arms II in both sexes.
   2. Arm suckers globular with smooth inner rings.
      
   1. Males
   1. Arm formula: 2.3.1.4. 
      
      

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

      
      

      Figure. Two views of the arm crown of the male C. tongaensis showing sucker sizes (compare with the photograph on the species page). Photograph by C. C. Lu.

   1. Females
   1. Arm formula: 2.3.4.1.
      
      
2. Web
   1. Males
      1. Web formula: D>A=E>C=B.
         
      2. Deepest web (sector D) 27-29% of longest arm; webs A, E 10% of longest arm and webs C,B 5-8% of longest arm.
         
   1. Females
      1. Web formula: D>C>B=A>E.
         
      2. Deepest web (sector D) 38% of longest arm, web C 26%, web B, A 14% and web E about 7% of longest arm.
         
         
3. Tentacles
   
   1. Protective membranes well developed.  
      
   2. Tentacular stalk circular in cross-section proximal to club.
      
   3. Stalk more slender than arms.
      
   4. Club suckers with fine triangular teeth around entire margin of inner ring.
      
      
4. Head
   
   1. Each eye large, with cornea and secondary ventral eyelid.
      
   2. Eye pore absent.
      
   3. Olfactory organ not found.
      
   1. Upper beak
      1. Rostrum pointed, slightly curved rostrum.
         
      2. Lateral wall damaged, presence of depression unknown.
      3.  Jaw angle nearly 90°. Cutting edge of shoulder irregular.
         
      4. Crest wide, slightly curved.
         
      5. Entire beak, except the margin, brown;rostrum and upper part of shoulder black; margin clear.
         
         

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

         
         

         Figure. Lateral view of the upper beak of C. tongaensis. Photograph from Lu and Boucher-Rodoni (2006).

   2. Lower beak
      1. Rostrum with slightly curved, irregular, sharp, thick edge.
         
      2. Acute jaw angle.
      3. Shoulder with large tooth. Anterior edge of shoulder irregular.
      4. Wings widely spread.
         
      5. Hood notch absent.
         
      6. Crest slightly curved.
         
      7. Indentation at posterior edge of lateral
         wall shallow.
         
      8. Entire beak, except the margin, brown; rostrum and anterior part of shoulder blackish brown, rostral tip black; margin clear.
         
         

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

         
         

         Figure. Two views of the lower beak of C. tongaensis. Left - Oblique side view. Right - Frontal-ventral view. Photographs from Lu and Boucher-Rodoni (2006).

   3. Radula
      1. Radula homodont with seven, approximately equal teeth without accessory cusps, in a transverse row.
         
      2. Marginal plates absent.
         
         

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

         
         

         Figure. View of the radula of C. tongaensis. Photograph from Lu and Boucher-Rodoni (2006).

5. Funnel
   
   1. Lateral funnel adductors present.
      
   2. Funnel organ with two, long, slender ventral pads located anterior to dorsal organ; dorsal organ triangular with thick medial ridge in anterior half terminating in a long, slender papilla at organ anterior apex.
      
   3. Funnel valve triangular is shape.
      
      

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

      
      

      Figure. Funnel organ of C. tongaensis. Left - Dissection paratype 1 showing both ventral organs adjacent to one another at the midline. Right - Diagram showing the arrangement and shape of the organs. Photograph and drawing from Lu and Boucher-Rodoni (2006).

6. Fins
   1. Large, ear-shaped (free anterior and posterior lobes); attached obliquely relatively to dorsal mantle midline.
      
   2. Anterior tip of fins 26-27% of ML from anterior mantle margin; posterior tip 9-23% of ML from posterior mantle margin.
      
      
7. Pigmentation
   1. Alcohol preserved specimen brown; dark chocolate brown chromatophores scattered over brown-colored background.
   2. Dorsal mantle surface lighter than ventral surface.
      
      
8. Gladius
   1. Gladius rudimentary: thin, narrow gladius on anterior half of mantle only.
      
      
9. Viscera
   1. Gills with 25-26 lamellae per demibranch, plus a terminal lamella.
      
   2. Median mantle septum present with ventral mantle adductor at anterior end. Mantle adductor passes lateral to rectum just beyond photophore pores.
      
   3. Anal flaps large.
      
   4. Ink sac large.
      
      
10. Measurements and counts
    

    	Holotype	Paratype 1	Paratype 2
    Sex	Female	Male	Female
    Maturity	Mature	Probably mature	Subadult
    Dorsal mantle length	33.8	Head only	24.3
    Ventral mantle length	29	-	24
    Head length	18	17	13
    Head width	18	20	14
    Nuchal commissure width	14	13	11
    Mantle width	23	-	17
    Eye diameter	12	11	11
    Funnel length	23	19	15
    Funnel width	12	9	9
    Free funnel length	17	16	12
    Fin length	20	-	10
    Fin width	12	-	10
    Length, Arm I	35	27	15
    Length, Arm II	41	30	18
    Length, Arm III	41	30	18
    Length, Arm IV	25	22	17
    Arm formula	2=3.1.4.	2=3.1.4	2.3.4.1
    Web sector A	4	3	2.4
    Web sector B	2.2	2.3	2.6
    Web sector C	3.5	2.3	4.6
    Web sector D	11	9	7
    Web sector E	4.3	3.2	1.2
    Largest sucker diam., arm I	1.6	1.6	0.6
    Largest sucker diam., arm II	2.7	4.3	0.8
    Largest sucker diam., arm III	3.9	3.1	0.7
    Largest sucker diam., arm IV	1.2	0.9	0.5
    Tentacle length	-	45	-
    Club length	-	13	-

Comments

The above description with the exception of a few photographs is taken from Lu and Boucher-Rodoni (2006).

References

Lu, C. C. and R. Boucher-Rodoni. 2006. A new genus and species of sepiolid squid from the waters around Tonga in the central South Pacific (Mollusca: Cephalopoda: Sepiolidae). Zootaxa, 1310:37-51.