Mastigoteuthis atlantica Joubin, 1933

Introduction

M. atlantica was described from a single large specimen.

Brief diagnosis:

A member of the M. glaukopis Group with ...

• an Atlantic Ocean distribution.
  
• well-developed trabeculate protective membranes on tentacular clubs.

Characteristics

1. Arms
1. Arm suckers about 1.5 mm in longest diameter (Joubin, 1933).
   

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   Figure. Oral and lateral views of arm suckers of M. atlantica, holotype. Drawings from Joubin (1933).

2. Tentacles
1. Club 31% of tentacle length (Joubin, 1933).
2. Sucker-bearing area of club tapers proximally to two series of suckers.
   
3. Club with wide, trabeculate membrane.

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Figure. Aboral view of midregion of tentacular club of M. atlantica, 105 mm ML. Photograph by R. Young.

4. Club suckers 0.364 mm in diameter with 2-3 lateral, inward directed pegs (Joubin, 1933).

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Figure. Oral and lateral views of club suckers of M. atlantica, holotype. Drawings from Joubin (1933).

3. Head
   1. Beaks. Description of the beaks can be found here.
      
   2. Funnel pocket present.
      
      
4. Funnel locking-apparatus
1. Tragus present, antitragus slight and flat, not undercut.

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Figure. Funnel/mantle locking-apparatus of M. atlantica, 101 mm ML, immature female, 32°59'N, 39°49'W, NMNH 884052. Left - Funnel component. Right - Mantle component. Photographs by R. Young.

5. Mantle
1. Tubercules absent from mantle and other areas.
   
   
6. Fins
1. Fins slightly longer than broad.

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Figure. Ventral view of the fins of M. atlantica, 105 mm ML, immature male, 34°20'N, 35°24'W, NMNH 884059. Photograph by R. Young.

7. Photophores
1. Eyelid photophore oval; 4 mm long in holotype (Joubin, 1933).
2. Integumental photophores absent.

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Figure. Left - Eyelid photophore of M. atlantica, holotype. Drawing from Joubin (1933). Right - Ventrolateral view of the head of M. atlantica showing eyelid photophore (arrow), 101 mm ML, NMNH 884052. Photograph by R. Young.

1. Pigmentation
1. Squid dark carmine in color becoming almost black at points (Joubin, 1933); most pigment in chromatophores.
2. Tentacles covered with dark red-brown pigment not in chromatophores.

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Figure. Pigmentation of M. atlantica, 105 mm ML, NMNH 884059. Left - Ventral view of a portion of the mantle at the level of the fins. Right - Aboral view of a portion of the tentacular club. Photographs by R. Young.

2. Measurements
Measurements according to (Joubin, 1933) are: Mantle length (="visceral sac") - 112 mm; Head width - 24 mm; Head length - 22 mm; Arm I, length - 37 mm; Arm II, length - 56 mm; Arm III, length - 50 mm; Arm IV, length - 95 mm; Tentacle length - 254 mm; Club length - 80 mm; Fin length - 80 mm; Fin width - 68 mm.

Comments

We examined two large specimens of M. atlantica in the NMNH but they were badly damaged and the sucker rings had deteriorated. M. atlantica is very similar to M. famelica from the central North Pacific in having large eyelid photophores, absence of all other photophores and fins that are slightly longer than wide. These two species clearly differ, however, in the size of the protective membrane on the tentacular clubs (well developed in M. atlantica and nearly absent in M. famelica). The small M. glaukopis from the Indian Ocean as described by Chun (1910) is very similar except for differences in the size and dentition of the club suckers. Since these latter features change with size, we can find no differences that separate M. glaukopis Chun, 1908 and it is probably synonymus with M. atlantica Joubin, 1933 or M. famelica Berry, 1909, but has priority over both. Until larger specimens of M. glaukopis are available from the Indian Ocean, we maintain all three species. We suspect, however, on the basis of the distinct protective membrane on the tentacular club in the illustrations of Chun (1910) that M. glaukopis and M. atlantica may be synonymous.

Distribution

Type locality: 46°28'N, 08°01'W near the Bay of Biscay, NE Atlantic. The specimens we examined came from the central N. Atlantic at 32°59'N, 39°49'W and 34°20'N, 35°24'W.< /p>

References

Joubin, L. 1933. Notes préliminaires sur les Céphalopodes des croisières du Dana (1921-1922). 4e Partie. Annales de l'Institut Océanographique, new series, 13: 1-49.