Promachoteuthis sulcus Young, Vecchione and Roper, 2007

Introduction

Promachoteuthis sulcus (first known as Promachoteuthis sp. C on this page) is known from a single, small (25 mm ML, sex unknown) but distinctive individual from great depths in the south Atlantic Ocean.

Brief diagnosis:

• with nuchal fusion between head and mantle.
• with arm suckers much larger than club suckers.
• with tentacle base wider than arm base.
• with recessed club base and aboral tentacle groove.

Characteristics

1. Arms
   1. Arm suckers much larger than club suckers.
   2. Suckers in three series on all arms.
      

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

      

      Figure. Oral view of brachial crown of P. sulcus, holotype. Photograph by R. Young.

2. Tentacles
   1. At base tentacle thick, about 2x diameter of arm III.
   2. Tentacle stalk with deep groove on aboral surface.
   3. Club suckers tiny (0.014 mm diam), in numerous irregular rows.
   4. Sucker-bearing club recessed at tapering, proximal end; surrounding lateral and aboral tissue with thick folds.
   5. Tentacles heavily pigmented at base but not forming a well-defined band.
      

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

      

      Figure. Tentacular club of P. sulcus, holotype, preserved. Top - Oral view of the distal portion of the club, holotype. Bottom - Oral view of the proximal portion of the tentacular club. Photographs by R. Young.

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

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

      

      Figure. Side view of the head and anterior mantle of P. sulcus showing nuchal fusion. Photograph by R. Young.

4. Fins
1. Fins terminal with anterior and posterior lobes. Each fin approximately circular in outline.


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



Figure. Ventral and dorsal views of the fins of P. sulcus. Photograph.

Comments

Clubs were slightly abraided so the number of suckers in a transverse series could not be determined. The largest number of those present was 12 suckers across. The specimen is an immature female. The mantle was cut open prior to fixation by a previous investigator. The label in the specimen jar states that the ML is 40 mm; the squid currently measures 25 mm ML.

Distribution

Type locality: 36°49'S, 12°17'W off Tristan Da Cunha, south Atlantic Ocean. Captured from WALTHER HERWIG at 1750-2000 m depth (open net).