Note

Mastigoteuthis agassizii tropical form: Description continued

Michael Vecchione and Richard E. Young
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Figure Ventral view of the tropical form of M. agassizii, 90 mm ML, Gulf of Mexico. Collected by T. Sutton, HBOI. Photograph by R. Young.

  1. Arms
    1. Arm formula: IV>II>III>I.
    2. Arm II length ca. 90% arm II length.
    3. Arm II ca. 50-60% 0f ML.
    4. Arms with low protective membranes.
    5. Arm suckers with ca. 12-15 pointed teeth on distal margins of inner rings.
    6. Largest arm suckers of arms III and IV equal in size; ca. 0.6 mm across outer ring in 79 mm ML squid.
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      Figure. Oral-oblique view of an arm sucker of the tropical form of M. agassizii, 90 mm ML. Photograph by R. Young

  2. Tentacles
    1. Suckers on club smaller and more widely separated proximally (typical of the genus). Sucker diameter ca. 0.16 mm in midclub, ca. 0.10 at base in 79 mm ML squid.
    2. Sucker-bearing club completely encircles tentacle in terminal 10-15% of club; Purple line marke the remnant of the aboral surface and can be followed to club tip.
    3. Club covers over 50 of tentacle circumference at its abruptly terminating base.
    4. Click on an image to view larger version & data in a new window
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      Figure. Tentacular club of the tropical form of M. agassizii. Left - Aboral view of club tip showing club completely encircling tentacle, 79 mm ML, Gulf of Mexico. Right - Oral view of club base showing abrubt termination, 90 mm ML, Gulf of Mexico. Photographs by R. Young.

  3. Head
    1. Rounded but distinct occipital crest without occipital folds.
    2. Funnel pocket present.
    3. Stalk of olfactory organ more slender than sensory bulb and weakly pigmented.
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      Click on an image to view larger version & data in a new window
      Click on an image to view larger version & data in a new window

      Figure. Ventral view of the olfactory organ of the tropical form of M. agassizii, 90 mm ML. Photograph by R. Young. Collected by T. Sutton, HBOI

  4. Fins
    1. Fins together nearly circular in outline.

  5. Tubercules
    1. Integumental tubercules absent.

  6. Photophores and pigmentation
    1. Integument with typical integumental photophores, ringed chromatophores and white sphere (see photograph of funnel organ above).
    2. Most integumental chromatophores ringed and well separated.
    3. Eyelid photophore present, small (ca 0.2 mm in 79 mm ML squid), with distinct window.
    4. Click on an image to view larger version & data in a new window
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      Figure. Lateral view of eyelid region of the tropical form of M. agassizii, 90 mm ML, preserved. Eyelid photophore is covered laterally by dark pigment but the window through which the bioluminescence passes is apparent (arrow) and has a covering of small photophores. Photograph by R. Young.

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      Figure. Ventral view of the head and bases of arms IV of the tropical form of M. agassizii, 79 mm ML, showing scattered pattern of large and small photophores. The skin was slightly abraided on this specimen making the pattern of the deep photophores apparent. Photograph by R. Young.

    5. Arms IV with two, somewhat irregular, series of photophores; distally becoming a single series and breaking into separate patches.
    6. Arms III with single series of photophores to arm tip on aboral-ventral margin.
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      Click on an image to view larger version & data in a new window

      Figure. Ventral view of a midregion of arm IV of the tropical form of M. agassizii, 79 mm ML. Photograph by R. Young.

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

      Figure. Ventral view of the distal portion (distal to the vertical white line in the insert) of arms IV of the tropical form of M. agassizii, 79 mm ML. The background has been cleaned-up in Photoshop. Photograph by R. Young.

    7. Photophores on funnel and mantle scattered.
    8. Few small photophores on midregion of cyclindrical, non-muscular mantle extension between fins but patch of large photophores just proximal to tail.
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      Click on an image to view larger version & data in a new window

      Figure. Ventral view of photophores on non-muscular, posterior extension of the mantle of the tropical form of M. agassizii. Photograph by R. Young. Collected by T. Sutton, HBOI

    9. Most pigmentation not in chromatophores.
    10. Inner mantle wall unpigmented; visceral sac with light pigmentation posteriorly.

  7. Measurements
    Squid SC 98 21  SC 95 T8 
    Sex Imm. female  Imm. male 
    Mantle length 90  79
    Tail lenght
    missing  missing 
    Fin length 60  48 
    Fin width 66  51 
    Head width 26  20 
    Eye diameter 15  10.5 
    Arm I, length: Left / Right 43.5  29.5 
    Arm II, length 58.5  43.5 
    Arm III, length 52.5  38.5 
    Arm IV, length 121.5  92.5 
    Tentacle length  189  205 
    Club length (% of tentacle length) 65.5  62% 
    Largest club sucker diam.    0.16
    Largest arm sucker diam.
      0.6 across ring
    *Where possible, right and left measurements averaged.
About This Page


National Museum of Natural History, Washington, D. C. , USA


University of Hawaii, Honolulu, HI, USA

Page: Tree of Life Mastigoteuthis agassizii tropical form: Description continued Authored by Michael Vecchione and Richard E. Young. The TEXT of this page is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.

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