Promachoteuthis megaptera: Description Continued

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.


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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."


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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

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).

Comments

References

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.