Chiroteuthis mega: Description continued

1. Photophores
   1. Eyeball: lateral series= 8 separate organs (may coalesce to irregular stripe + 1); intermediate series = stripe with nearly separate photophore at posterior end; medial series = stripe.
   2. Viscera: none
      

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      Figure. Left - Ventral view of the digestive gland, ink sac and intestine of C. mega showing absence of photophores on the ink sac. Drawing from Voss (1967).  Right - Photograph of the same region of C. mega. Photograph by R. Young.
      

   3. Club-tip photophore large (exposed photogenetic surface much more than half the photophore length), with little or no terminal papilla.
      

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      Figure. Oral view of the club-tip photophore of C. mega. Drawing from Voss (1967).
      

   4. Distal most cushion-like photophore of stalk partially embedded, located just proximal to first club sucker; no photophores embedded in aboral surface of club.
2. Pigmentation
   1. Club-tip photophore with heavy epidermal pigmentation in covering lids and adjacent tissue.
   2. All other club pigment in functional chromatophores.
   3. Club sucker stalks without pigment.
   4. Buccal membrane pigmented (epithelial pigmentation on oral and aboral surfaces).
   5. Olfactory organ unpigmented in small subadults but with pigment in chromatophores at 115 mm ML.
3. Arms
   1. Arms I 30-50% of ML.
   2. Arms III 40-60% of ML.
   3. Arms IV 120-140% of ML.
   4. Large arm suckers with 20-30 teeth around entire ring. Teeth slender, pointed, separate distally; truncated, separate laterally; broadly rounded, in contact proximally.
   5. Largest suckers not globular.

   Scanning electron micrographs of the arm suckers can be seen here.

4. Tentacular clubs
   1. Club length 84% of ML.
   2. Suckers with 15 pointed teeth over distal 3/4 of ring; enlarged, conspicuous central tooth; teeth just lateral to central tooth smallest of distal teeth; club suckers equal to or slightly larger than largest arm III sucker.

   Scanning electron micrographs of the club suckers can be seen here.

   3. Stalks weakly divided into two parts: proximal portion with thick, delicate keel with terminal swelling (=flag). Stalks of lateral suckers about twice as long as stalks of medial suckers.
   
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   Figure. Oral view of medial (left) and lateral (right) club suckers and stalks of C. mega. Drawing from Voss (1967)
   

   4. Protective membranes
   1. Membranes in two sets; proximal set slightly larger than distal set.
   2. Proximal set short (5-7% of club length), with 12-15 trabeculae, numbers 5-11 adjacent (in contact) and more elongate than the others. At broadest point, four trabeculae present between adjacent lateral suckers.
   3. Distal set long (93-95% of club length) with 58-70 broad, well-separated trabeculae. Proximal 1 or 2 trabeculae bifurcate at the tip. Trabeculae arise alternately with lateral suckers; shaped like broad, truncated bands that narrow slightly distally; separated by width of about one trabecula.
   
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   Figure. Oral views of the tentacular club of C. mega. Top - Drawing from Voss (1967). Bottom - Photograph of short proximal segment by R. Young.
   

5. Head
   1. Head length 28-33% of ML
6. Funnel
   1. Tragus of the funnel-locking apparatus well developed but not as prominent as in Chiroteuthis sp. B, with broad base.
      

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      Figure. Frontal view of the funnel locking-apparatus of C. mega. Drawing from Voss (1967)
      

7. Fins
   1. Fin length ca. 45% of ML
   2. Fin width ca. 35% of ML

Comments

Fins with distinct, small posterior lobes; marginal membrane of tail thick, lacks trabeculae. The penis on mature males extends well beyond the mantle opening.