Grimpoteuthis discoveryi Collins 2003

Introduction

Grimpoteuthis discoveryi is a small, lower slope and abyssal species that was recently described from over 50 individuals taken in the N. E. Atlantic (Collins, 2003).

Characteristics

1. Arms and web
   

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   Figure. Oral view of arms and web of G. discoveryi, paratype, female, 65 mm ML. Drawing from Collins (2003).
   

   1. Arms long, subequal in length.
   2. Web extends 2/3 of arm length; extends further on dorsal arms.
   3. Web formula: ABCDE.
   4. Single web nodule prominent on ventral side of each arm (see arrow above); located at sucker 31 (arm I), 29 (arm II), 27 (arm III) or 25 (arm IV).
   

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   Figure. Oral view of arm I of G. discoveryi, paratype, female, 65 mm ML. Drawing from Collins (2003).

   5. Sucker count 56-61.
   6. Suckers barrel-shaped with distinct sexual dimorphism.
   7. Sucker height much greater than sucker diameter in mature males; sucker diameter (max. diameter 6.4% of head width) greater in males.
   8. Maximum sucker diameter between suckers 6 and 40.
   9. Cirri moderate (mean CLI 7.3).
   10. First cirri between suckers 3 and 5.
   

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   Figure. Lateral view of suckers and cirri of G. discoveryi. Left - Female, 65 mm ML, paratype. Right - Male, 50 mm ML, holotype. Drawings from Collins (2003).

2. Shell
   1. Robust U-shape with outer walls of wings parallel.
   2. Inner and outer surfaces of saddle convex.
   3. Lateral wing terminates in two lobes.
   

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   Figure. Ventral (left), lateral (middle) and dorsal (right) views of the shell of G. discoveryi, female, 65 mm ML. Drawings from Collins (2003).

Comments

Among other Atlantic species, with the possible exception of G. wuelkeri, G. discoveryi differs, where known, in having a shell with wings termining in two lobes. In addition it differs from:

• G. boylei in the absence of a depression on the outer surface of the shell saddle, in the absence of a radula and posterior salivary glands, in having generally 7 vs 8 gill lamellae, smaller size at maturity (152 vs 265 mm total length in females), and smaller eggs (8-11 mm vs 18-20 mm)(Collins, i2003).
• G. challlengeri in having broad rather than slender gill lamellae, in the sucker number (56-61 vs 63-72), larger sucker size in males (mean sucker diam./head width of 6.4 vs 4.8), shorter cirri (1.2x in males, 1.6x in females vs 2.5x and 3.5x), generally 7 gill lamellae vs generally 8, and the absence of a radula (Collins, 2003).
• G. megaptera in geographic distribution (Eastern vs Western North Atlantic), having larger sucker size (mean 6.4 in males, 4.4 in females vs 3.7) and shorter cirri (1.2x in males, 1.6x in females vs 2x) (Collins, 2003).
• G. plena in geographic distribution (Eastern vs Western North Atlantic) and deeper depth habitat (>2600 m vs <2000 m) (Collins, 2003). Distinguishing morphological characters seem to be unknown.
• G. umbellata in geographic distribution (Eastern vs Western North Atlantic) and deeper depth habitat (>2600 m vs <2300 m), and in the form of the gill lamellae (narrow vs broad) (Collins, in press). In spite of these apparent difference, G. umbellata may be the senior synonym of G. discoveryi (Collins, 2003).
• G. wuelkeri in having a shell without a ridge on the outer surface of the saddle, in having generally fewer suckers (56-61 vs 60-70), no posterior salivary glands or radula, weak vs strong shoulder blades on the shell, fewer gill lamellae (7 vs 8) and possibly a deeper depth habitat (>2600 m vs <2300 m) (Collins, 2003).

Life History

Distribution

The type locality is the Porcupine Seabight at 49°35'N, 14°01'W, and a depth of 4190-4255 m. Caught at depths of 2600-4870 m in the Northeast 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.