Promachoteuthis megaptera: Description Continued

Richard E. Young and Michael Vecchione
  1. Tentacles
    1. Club, apparently, without keel, carpal locking-apparatus or terminal pad.

  2. Head and funnel
    1. Buccal connectives attach to the ventral margins of arms IV.
    2. Funnel locking-apparatus "oval but presenting a rather irregular outline because it is so delicate..."; mantle component is "a low, slightly angulated oval knob" (Okutani, 1983).

  3. Viscera
    1. Rectum without anal flaps.
    2. Very large branchial hearts.
    3. Large funnel organs.
    4. Ink sac absent.
    5. 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 mantle cavity, opened funnel and visceral mass of P. megaptera. Drawing modified from Okutani (1983).

  4. Gladius
    1. The gladius of  the holotype was described by Toll (1982): "The free rachis is short and strongly triangular in outline. ... The posterior tip of the gladius is  thin, flexible, and acutely pointed. The rachis is absent in the extreme tip. A thick, rigid domed mass of gelatinous material lines the ventral concavity of the gladius except in the extreme anterior and posterior ends. there is an unusual structure at the posterior end of the rachis. It consists of three (?) anteror facing digitiform lobes lying in a concavity filled with the same gelatinous material found along the ventral surface of the gladius."
    2. 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 gladius of P. megaptera with cross-sections above and arrows indicating the locations of the cross-sections. Drawing from Toll (1982).

  5. Photophores
    1. Photophores apparently absent.

  6. Measurements
  7. Specimen Okutani's Holotype
    Mantle length 52.4 15
    Mantle width (%ML) 19.8  (37.8) 9 (60)
    Head width 10.7 (20.4) 6 (40)
    Fin width 77 (146.9) 23 (153.3)
    Fin length 39.4 (75.2) 11 (73.3)
    Length, arm I: right (%ML) / left (%ML) 23.3 (44.5) / 23.6 (45.0) 13 (86.6) / 14( 93.3)
    Length, arm II 24.8 (47.3) / 21 (40.1) 14.5 (96.6) / 15 (100)
    Length, arm III 24.9 (47.5) / 16.7 (31.9) 14.5 (96.6) / 14.5 (96.6)
    Length, arm IV 20.3 (38.7) / 23.3 (42.6) 7 (46.7) / 12 (80)
    Length, tentacle 108.8 (207.6) / 139.6 (266.4)  -
    Length, club 55.5 (105.9) / 81.2 (155)  -
    Sucker count, arm I 42 / 42 37 / 37
    Sucker count, arm II 42 / 32 39 / 39
    Sucker count, arm III 47 / 27 35 / 39
    Sucker count, arm IV 41 / 41 20 / 31
    Measurements in mm (number in parentheses: % of ML).
    All measurements and counts were taken from Okutani (1983).


The beaks have not been described.


Okutani, T. 1983. Rare and interesting squid from Japan. VIII. Rediscovery of Promachoteuthis megaptera Hoyle, 1885 (Oegopsida: Promachoteuthidae). Venus 42: 241-247.

Toll, R.B. 1982. The comparative morphology of the gladius in the Order Teuthoidea (Mollusca: Cephalopoda) in relation to systematics and phylogeny. PhD. Dissertation, University of Miami, 390 pp.

About This Page

University of Hawaii, Honolulu, HI, USA

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

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