Iridoteuthis iris: Description continued

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Figure. Dorsolateral view of I. iris.  Photograph by Thomas Burch.

1. Arms (Harman and Seki, 1990)
   1. Males: Each arm I with 20-28 suckers (mean 24.4); each arm II with 22-31 suckers (mean 25.1); each arm III with 24-31 suckers (mean 27.1); proximal half of each arm IV with 10-20 relatively large suckers, distal half with 70+ smmall suckers.
   2. Females: Each arm I with 18-32 suckers (mean 28.3); each arm II with 24-45 suckers (mean 39.0); each arm III with 18-27 suckers (mean 22.0); each arm IV with proximal half with 6-14 relatively large suckers in proximal half and next quarter with 10-30 smaller suckers.
   3. Arm bases proximal to suckers, in females, covered with small flattened papillae.
      
   

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   Figure. Oral view of arm bases of I. iris, female, showing papillate region. Photograph by R. Young.
   

2. Tentacles (Harman and Seki, 1990)
   1. Tentacular club with two sucker fields: distal half with minute, crowded suckers (ca. 19 suckers across), proximal suckers slightly larger, less crowded (ca. 11 across).
   

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   Figure. Oral view of the tentacular club of Iridoteuthis iris. Drawing from Harman and Seki (1990).

   

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   Figure. Oral view of the tentacular club of I. iris. Arrow points to tentacle organ. Note sucker sizes. Blue color from methylene blue stain. Photograph by R. Young.

   

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   Figure. Oral views of tentacular club suckers of Iridoteuthis iris. Left - Sucker from distal field of small suckers. Right - Sucker from proximal field of larger suckers. Scanning electron micrographs from Harman and Seki (1990).
   

3. Funnel
   1. Funnel locking-apparatus with deep, angled, anterior pit.
   
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   Figure. Funnel/mantle locking-apparatus of I. iris, Hancock Seamount, 29°46'30"N, 179°03'36"E, NMNH 817723, left in photographs is anterior. Top - Side-oblique view of the mantle component. Bottom - Frontal view of the funnel component. Photographs by M. Vecchione.

4. Mantle (Harman and Seki, 1990)
   1. Dorsal mantle broadly fused to head (fusion approximately reaches posterior midpoints of eyes).
   2. Ventral-mantle shield large (ca. 80% of ventral mantle length); extends nearly to anterior margin of eyes; with medial anterior indentation.
      
      

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      Figure. Mostly ventral view of I. iris, preserved, showing the ventral shield and its anterior indentation.Photograph by R. Young.
      

   3. Mantle with pronounced middorsal arch.
      

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      Figure. Side view of I. iris showing the pronounced dorsal hump on the mantle. Left - Drawing, 24 mm ML, from Harman and Seki (1990). Right - Photograph, preserved, 10 mm ML, by R. Young.

5. Fins
   1. Fins with pointed posterior lobes; fins extend to posterior margin of mantle (beyond margin in preserved animals).
   

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   Figure. Dorsal view of I. iris, preserved, showing the pointed posterior fin lobes. Photograph by R. Young.

6. Photophore
   1. Visceral photophore with strongly elevated papillae each composed of two  two distinct tubes.
   2. Photophore tubes located at lateral edges of photophore. Presumably the tubes enter the photophore between the "lens" and the ink sac but this needs confirmation.
      
   

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   Figure. Posteroventral view of the visceral photophore of I. iris, preserved, showing pores to the photophore laterally positioned, elevated and with two distinct ducts. Photograph by R. Young.

7. Pigmentation
   1. Posterior region of head between edge of secondary eyelid and collor with distinct chromatophore-free band.
      
   

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   Figure. Ventrolateral view of the posterolateral portion of the head of I. iris, showing  chromatophore pigmentation in the region where the lateral funnel adductor attaches. Arrow points to chromatophore-free band. Photograph by R. Young.

8. Measurements and counts (Harman and Seki, 1990)

   Sex	Male	Male	Male	Male	Female	Female	Female	Female
   Mantle length	8.5	11.5	15.5	24.1	9.5	13.0	15.5	28.4
   Total length	19.5	31.0	41.0	60.1	24.0	28.5	32.0	46.6
   Head width	12.5	14.5	18.0	20.2	13.5	15.0	17.3	17.4
   Ventral mantle length	13.0	20.0	24.5	30.0	13.5	20.0	21.5	29.8
   Mantle width	7.0	11.0	13.5	16.2	7.5	10.5	11.4	15.0
   Shield length	11.5	17.0	20.5	24.8	12.3	17.0	20.9	26.9
   Eye diameter	7.5	11.0	13.5	15.7	6.7	10.0	11.5	14.5
   Eye lens diameter	3.0	3.0	4.4	4.5	2.5	3.5	2.0	3.4
   Fin width	26.5	28.5	37.0	42.5	21.3	29.0	32.1	36.0
   Fin length	12.5	16.0	19.0	21.8	12.4	16.5	17.7	18.4
   Fin base	6.0	8.0	19.5	12.2	6.2	7.0	8.4	7.7
   Tentacle club length	4.5	5.0	6.5	7.1	3.5	6.0	6.0	9.5
   Tentacle length	21.0	29.0	26.0	41.5	11.0	35.0	31.0	51.8
   Arm I, length	6.0	14.0	19.5	23.2	7.5	9.0	10.3	13.9
   Arm II, length	6.0	14.0	19.5	23.3	8.0	9.0	10.4	15.5
   Arm III, length	7.5	15.0	22.5	28.2	9.0	10.0	13.8	14.9
   Arm IV, length	6.0	11.0	15.0	20.1	8.0	9.5	11.4	16.3

9. Type illustrations
   
   

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   Figure. Side (left), ventral (middle) and dorsal views of the holotype of I. iris. Drawings from Berry (1914).
   

References

Berry, S. S. 1914. The Cephalopoda of the Hawaiian Islands. Bull. U. S. Bureau Fisheries, 32: 257-362, 11 plates.