Grimpoteuthis plena (Verrill, 1885)

Introduction

G. plena was described from a single octopod and many details are lacking. A redescription based on new specimens from the type locality is badly needed.

Characteristics

1. Arms and web
   1. Arms I and II longer than arms III and IV.
   2. Arms I with about 55 suckers, 30 within web.
   3. Arm tips with 15-20 closely-spaced suckers.
   4. Suckers in arm center separated by about one sucker diameter.
   5. Largest suckers (2.5 mm diam.) at basal third of arm, suckers near mouth very small.
   6. Slight tendency for suckers to become alternate at basal third of lateral arms.
   7. Cirri short (3-4 mm).
      
      
2. Eyes
   1. Relatively small (12 mm diam.).
      
      
3. Shell
   1. Not described.
      
      
4. Color (in alcohol)
   1. Body and aboral surfaces of web yellowish flesh-color with translucent, gelatinous appearance.
   2. Fins deep brown, darker toward tips.
   3. Oral surfaces of arms and web dark purplish-brown.
   4. Suckers dull brownish-yellow.


5. Measurements
   • Total length - 185 mm.
   • Mantle length to mantle opening - 57 mm.
   • Mantle width at base of fins - 58 mm.
   • finspan - 130 mm.
   • Fin length - 32 mm.
   • Fin width - 24 mm.
   • Eye diameter - 12 mm.
   • Length, Arm I - 125 mm.
   • Length, Arm II - 120 mm.
   • Length, Arm III - 110 mm.
   • Length, Arm IV - 95 mm.
   • Web depth, Sector A - 70 mm.
   • Web depth, Sector B - 60 mm.
   • Web depth, Sector D - 55 mm.
   • Web depth, Sector E - 35 mm
   • Sucker count - 55 - 60*
   • Diameter largest sucker - 2.5 mm.
   • Length of longest cirrus - 4*  mm.
   • Location of largest suckers - Sucker positions 10 - 28*.

Comments

Collin Martin writes: "I have examined the type (only specimen) of plena, which is in poor condition, and is presently a valid species of Grimpoteuthis. Further material is needed from the type location to evaluate it properly."

Among other Atlantic species, G. plena cannot be clearly separated but may differ from:

• G. boylei in geographic distribution (Western vs Eastern North Atlantic) and the shorter cirri (1.2-1.6x vs 1.9x,males, 2.2x, females). What little is known about G. plena suggests that it is very close to G. sp. B.(Collins, 2003).
• G. challengeri in the lesser number of suckers (55-60 vs 63-72) and the shorter cirri (1.2-1.6x vs 2.5x in males, 3.5x in females) (Collins, 2003).
• G. discoveryi in geographic distribution (Western vs Eastern North Atlantic) and shallower depth habitat (<2000 m vs >2600 m) (Collins, 2003).
• G. megaptera in having a much larger and longer body, smaller fins and relatively larger eyes, larger, less prominent and more closely-packed suckers, and shorter, fatter cirri (Verrill, 1885).
• G. wuelkeri in having fewer suckers (55-60 vs 60-70) (Collins, 2003).

Life History

References

Collins, M. A. In press. The genus Grimpoteuthis (Octopoda: Grimpoteuthidae) in the North-east Atlantic, with descriptions of three new species.

Verrill, A.E. 1885. Third catalog of Mollusca recently added to the fauna of the New England coast and the adjacent parts of the Atlantic, consisting mostly of deep-sea species with notes on others previously recorded. Transactions of the Connecticut Academy, 6(2): 395-452.