Grimpoteuthis wuelkeri (Grimpe 1920)

Introduction

G. wuelkeri although originally described in 1920 based on an animal described under an existing name in 1910, this species was poorly known until the recent redescription by Collins (in press). The redescription was based on seven specimens including the holotype. This species is found on the continental slopes in the N. E. and N. W. Atlantic.

Characteristics

1. Arms and web
   

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   Figure. Oral view of arms and web of G. wuelkeri, female, 115 mm ML. Drawing from Collins (2003).

   1. Arms long, subequal in length.
   2. Web extends 2/3 of arm length; extends farther on dorsal arms.
   3. Web formula: A=B>C=D>E.
   4. Single web nodule present on ventral side of each arm (see arrow); located at sucker 28 (arm I), 26 (arm II), 24 (arm III) or 22 (arm IV).
   

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   Figure. Oral view of arm I of G. wuelkeri, holotype, female, 165 mm ML. Drawing from Collins (2003).

   5. Sucker count 60-70.
   6. Maximum sucker diameter between suckers 8 and 25.
   7. Cirri short, length 6.1 % of head width (females) or 10% (single male).
   8. First cirri between suckers 4 and 7.
      

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      Figure. Lateral view of suckers and cirri of G. wuelkeri, female, 115 mm ML. Drawing from Collins (2003).

2. Shell
   1. Robust U-shape with lateral edges of wings nearly parallel to one another.
   2. Inner and outer surfaces of saddle convex; distinct ridge on outer surface.
   3. Lateral wing terminates in two lobes, one with a small point.
   

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   Figure. Ventral (left), lateral (middle) and dorsal (right) views of the shell of G. wuelkeri, holotype. Drawing from Collins (2003).

Comments

The above description is from Collins, 2003. More details of the description of G. wuelkeri can be found here.

Among Atlantic species, G. wuelkeri differs, where known, in having a shell with a ridge on the outer surface of the saddle. In addition it differs from:

• G. boylei in having shorter cirri in females (1.2x vs 2.2x), more suckers (60-70 vs 55-58), 6-7 vs generally 8 gill lamellae, and smaller eggs (14 vs 18-20 mm), and the lesser depth habitat (<2100 m vs >4000)(Collins, 2003).
• G. challengeri in having broad vs slender gill lamellae, 6 or 7 gill lamellae vs generally 8, shorter cirri (2.5x in males, 1.2x in females vs 2.5x and 3.5x), posterior salivary glands and a lesser depth distribution (<2100 m vs >4000 m) (Collins, 2003).
• G. discoveryi in having generally more suckers (60-70 vs 56-61), posterior salivary glands and radula, strong vs weak shoulder blades on the shell, more gill lamellae (8 vs 7) and possibly a lesser depth habitat (<2100 m vs >2600 m) (Collins, 2003).
• G. megaptera in having a lesser depth distribution (<2100 m vs >4000 m) and, perhaps a larger sucker diameter (1.5-2.2 vs 1 for octopods with arms I about 100 mm).
• G. plena in having more suckers (60-70 vs 55-60) (Collins, 2003).
• G. umbellata in having fewer gill lamellae (6-7 vs 8). In spite of this apparent difference, G. umbellata may be the senior synonym of G. wuelkeri (Collins, 2003).

Life History

Distribution

The type locality is at 35°46'N, 08°16'W; depth - 2055 m. This species is known fron the Northeast Atlantic with one specimen from the Northwest Atlantic (Collins, 2003).

References

Collins, M. A. 2003. The genus Grimpoteuthis (Octopoda: Grimpoteuthidae) in the North-east Atlantic, with descriptions of three new species. Zool. Journ. Linnean Soc., 139: 93-127.