Ommastrephes bartramii: Description continued

1. Arms
   1. Arm suckers in two series.
   2. Arm sucker number (male 240 mm  ML) (Sasaki, 1929): Arm I - about 48; arms II, III - about 54; Arm IV - about 64.
      
   3. Arm suckers (Sasaki, 1929): Basal arm suckers teeth "... mostly triangular, numbering about 20;... [with] short plate-like supplementary teeth." Suckers in rows 3-10 with 24-28 teeth, "...bent crescentwise, sharply pointed, markedly unequal... ." Distal suckers with 9-12 teeth, ...slenderly conical, nearly uniform but sometimes minute supplementary teeth [present] ..."
      
   

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   Figure. Sucker ring from arm II of O. bartramii showing row number from which sucker was taken, off Japan, male, 240 mm ML. Drawing from Sasaki (1929).

2. Tentacles
   1. Club with suckers in four series except at extreme base. Manus with about 10 transverse rows; dactylus with 20-29 transverse rows with dorsal series smaller than ventral series (Sasaki, 1929).
   2. Marginal manus suckers and dactylus suckers with 21-24 teeth (Sasaki, 1929).
      
   

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   Figure. Oral view of the tentacular club of O. bartramii, 211 mm ML, Eastern Pacific off Southern California. Drawing from Young (1972).

   

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   Figure. Oral view of the tentacular club of O. bartramii, 145 mm ML, female, preserved, Hawaiian waters. Photograph by R. Young

   

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   Figure. Oral view of the mid-portion of the club manus of O. bartramii, same squid as above. Photograph by R. Young.

3. Photophores (Young, 1972).  Numerous, small, closely packed integumental photophores of irregular shape embedded in ventral muscular tissue.
   
   1.  Ventral mantle. Area dorsal to silvery stripe in skin with lower density of photophores. Area in midventral mantle posterior to silvery stripe lacks photophores. Concentration of photophores greatest near anterior margin of mantle and extend onto lateral sides of mantle. Dorsal photophores  absent.
   2. Head. Irregular patch on either side of head where lateral funnel adductors attach to head. Small patch of photophores anterior to foveola. Irregular patch on head at base of each arm IV.
   3. Arms. Arm IV with long band of photogenic tissue all along arm within base of lateral keel.
   4. Funnel. Patch of photophores forming a V-shape dorsal to dorsal pad of funnel organ.
      


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Figure. Ventral view of O. bartramii, Eastern Pacific off Southern California, 210 mm ML, showing subcutaneous photophores. Drawing from Young (1972).

4. Measurements

   	Sasaki, 1929
   Sex	Female
   Mantle length	415
   Mantle width	104
   Head length	75
   Head width	89
   Fin length	183
   Fin width	300
   Arm I, length	180
   Arm II, length	200
   Arm III, length	190
   Arm IV, length	193
   Club length	138
   Largest sucker diameter, arm I	6
   Largest sucker diameter, arm II	7
   Largest sucker diameter, arm III	7
   Largest sucker diameter, arm IV	6
   Largest sucker diameter, club	9

References

Sasaki, M. 1929. A monograph of the dibranchiate cephalopods of the Japanese and adjacent waters. Journal of the College of Agriculture, Hokkaido Imperial University, 20(supplement):1-357.

Young, R.E. 1972. The systematics and areal distribution of pelagic cephalopods from the seas off southern California. Smithsonian Contributions to Zoology, 97:1-159.