Magnoteuthis magna (Joubin, 1913)

Introduction

Mg. magna  appears to be one of the more common mastigoteuthids in the temperate to tropical Atlantic. The description of the holotype by Joubin (1920) can be seen here.

Brief diagnosis:

A Magnoteuthis ...

• without photophores.
• with smooth-ringed arm suckers.

Characteristics

1. Arms
   1. Arm suckers with smooth inner rings.
   2. Largest suckers of arms IV larger than those of other arms.
      
   

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   Figure. Oral views of large suckers from  arms of Mg. magna, Left - Dive 3750, immature female, 111 mm ML; light microscope. Right - DE011-003, arm III, sucker 6, 135 mm ML; scanning electron microscope. Photographs by R. Young.

More scanning electron microscopy of arm and club suckers can be seen here.

2. Head
   1. Beaks. Description of the beaks in 2D can be found here.
      Description of the beaks in 3D can be found here: Lower beak; upper beak..
      
3. Funnel
   1. Mantle component of funnel locking-apparatus with straight, anterior groove and broad, posterior cup
   

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   Figure. Funnel locking-apparatus of Mg. magna. Left - Frontal view of funnel component, 111 mm ML. Middle - Frontal view of mantle component, 111 mm ML. Right -  Sta. WH512, 32°47'N, 16°24'W, head only. Photographs by R. Young.

4. Photophores and pigmentation
   1. Skin, except oral surfaces, covered with dense packing of chromatophores containing a deep, brilliant red pigment.
   2. Photophores absent.
   3. No trace of ringed chromatophores or white spheres.
      
   

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   Figure. Left - Frontal view of the chromatophores of Mg. magna, off New England, fresh, showing numerous chromatophores. Region of squid unknown. Photograph by M. Vecchione. Right - Ventrolateral view of a damaged portion of the ventral head of Mg. magna, 40°N,67°W, 160 mm ML, showing dense packing of chromatophores and the subchromatophore layer (damaged region) but without any indication of photophores. Photograph by R. Young.

Comments

More details of the description of Mg. magna can be found here.

Distribution

Type locality: Sargasso Sea of the North Atlantic at 31°45'N, 42°39'W. Apparently Mg. magna occurs throughout the tropical and warm temperate Atlantic, At least from 50°N, 27°W (MARECO record) to 40°S, 26°W (FFS WALTHER HERWIG record). Reported from the Indian Ocean (Nesis, 1982/87) but this could be a species of Magnoteuthis that was not recognized at the time of this publication.

References

Joubin, L. 1920. Céphalopodes provenant des Campagnes de la Princesse Alice (1898-1910). 3e Serie. Monaco.