Promachoteuthis sp. D

Introduction

Diagnosis

• with nuchal fusion between head and mantle.
• with mostly 2 series of suckers on arms..
• with tentacle at base narrower than arm III base.

Characteristics

1. Arms and tentacles
   1. Arm suckers mostly in two series but tend toward three series in mid-arm.
   2. Tentacles missing due to damage; remaining stubs about 75% as thick as bases of arms III.
      

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

      

      Figure. Oral view of left arm IV of Promachoteuthis sp. D. Photograph by R. Young.

2. Head
   1. Head fused to mantle in nuchal region.
      

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

      

      Figure. Dorsolateral view of the head and anterior mantle of Promachoteuthis sp. D showing nuchal fusion. Photograph by R. Young.

3. Beaks
   1. Beaks, buccal mass very large (length about 6.5 mm). Beak descriptions can be found here: Lower beak; upper beak.
      

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

      

      Figure. Lateral (left) and ventral (right) views of the head and brachial crown of Promachoteuthis sp. D showing large size of buccal mass. Note the broken stubs of the tentacles in the photographs. Photographs by R. Young.

Comments

Unfortunately the specimen is not in good condition. Previous investigators cut open the mantle then partially dissected the squid prior to fixation and, subsequently, the gladius was removed. In addition, the tentacles are missing. In spite of these problems, this is a very distinctive species. Considerable shrinkage has occurred which overemphasizes the size of the buccal mass (see Measurements and counts).

Life History

Ovary and nidamental glands had been removed by an earlier investigator and placed in a separate vial. The vial contains mostly large, free, equally-sized, mature eggs (ca. 170 eggs at 1.8 mm x 1.5 mm) with very few intermediate size and a small number of small oocytes still attached to the ovarian strands. The photograph on the right shows

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

Figure. Ventral view of most of the mantle cavity and two eggs of Promachoteuthis sp. D placed beside it for size comparison. The large posterior dark area in the visceral sac is where the ovary was removed. Compare photograph with title photograph to clarify orientation. Photograph by R. Young.

Distribution

Type locality: 16°35'E, 34°15'S in the south Atlantic Ocean. Captured from the WALTHER HERWIG at 1550 m depth.