Grimpoteuthis megaptera (Verrill, 1885)

Introduction

The original description of G. megaptera was based mostly on two specimens but another two were captured at a nearby station and a small one from another station. Two and probably three of these specimens belong to another species (see below). A more complete description of this species is needed.

Characteristics

1. Arms and web
   1. Arms I slightly the longest.
   2. Suckers small (1.0 mm diam.), urn-like, strongly elevated above arm surface.
   3. Distance between suckers in midarm often 2 times sucker diameter.
   4. Suckers small and closely packed proximally and distally.
   5. Maximum cirrus length, 2 mm.
   6. Web nodules present on ventral side of each arm.
   

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   Figure. Oral view of the arms and web of G. megaptera. Drawing from Verrill, 1885.

2. Eyes
   1. "Small", separated by more than 2 times eye diameter.
      
      
3. Shell
   1. Not described.
      
      
4. Color
   1. Oral surfaces of arms and web chocolate-brown.
   2. Suckers light yellow with brown rims.
   3. Mantle, fins and head bluish white covered with rather large and irregularly arranged, purplish-brown specks and spots.
   4. Web paler and more translucent aborally.
      
      
5. Measurements
   1. Measurements of G. megaptera can be found here.

Comments

There are some differences between the type description which was based on an animal preserved in alcohol and the type illustration which was based on sketches of the fresh animal.

Martin Collins writes: "The type material of G. megaptera appears to be lost, the two specimens in the Smithsonian were in fact C. murrayi. Verrill had four specimens, but the whereabouts of the other two (the real megaptera types) is not known. I have examined 20-30 specimens from the NW Atlantic, and there are at least two species in the material, one of which may be megaptera. Again new material from the type location is needed." Collins (in press) examined a recent specimen from near the type locality of G. megaptera. This specimen had 90 suckers on each arm (ML 120 mm, max. sucker diam. 3.9 mm, max. cirrus length 4 mm).

Among other Atlantic species, Grimpoteuthis megaptera differs from:

• G. boylei in geographic distribution (Western vs Eastern North Atlantic) and, perhaps, the smaller sucker size (Collins, 2002).
• G. challengeri in the shorter cirri (2x vs 2.5x in males, 3.5x in females) (Collins, 2002), but cannot be reliably separated from G. megaptera.
• G. discoveryi in geographic distribution (Western vs Eastern North Atlantic), having smaller sucker size (3.7 vs mean 6.4 in males, 4.4 in females) and shorter cirri (2x vs 1.2x in males, 1.6x in females) (Collins, 2002). The imprecise measurements of suckers and cirri in G. megaptera makes the latter two characters questionable.
• G. plena in having a much smaller and shorter body, larger fins and relatively smaller eyes, smaller, more prominent and less closely-packed suckers, and longer, more slender cirri (Verrill, 1885).
• G. wuelkeri in having a greater depth habitat (>4000 m vs <2100 m) and, perhaps a smaller sucker diameter (1 vs 1.5-2.2 for octopods with arms I about 100 mm) (Collins, 2002).

If the specimen examined by M. Collins from near the type locality (see above) is G. megaptera then the very large number of suckers will separate this species from all other Atlantic species.

Distribution

The type locality is: Southeast of Martha's Vineyard, off N. E. coast of United States, 36°05.5'N, 69°51.8'W, 4600 m depth and at 36°16.5'N, 68°21'W.

References

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.