Gonatopsis makko Okutani & Nemoto 1964

Gonatopsis makko: collected with crub cage trap at 39-47 N, 134-15 E at 880 m depth in Yamato Bank, Sea of Japan on 24 April, 2005. BW: 326.3 g, ML: 28.5mm, Fl: 95mm, ALI: 210 mm, ALII: 205mm, ALIII: 230mm, ALIV: 180mm. Deposited in Tottori Prifectural Museum, Japan.

Introduction

The original description of G. makko by Okutani and Nemoto (1964) is based on the holotype and two damaged paratype specimens found in the stomach contents of sperm whales harpooned in the Bering Sea. Afterwards, this species has been reported from deep-sea bottom trawl catches and stomach contents of sperm whales off northeastern Japan, Sea of Okhotsku and Sea of Japan (Ogata et al., 1973; Okutani et al., 1976, 1988). Nesis (1997) considered that most of those records of G. makko were the larger individuals of Gonatopsis japonicus which was described by Okiyama in 1969 from the Sea of Japan. Due mainly to bad condition of the types of G. makko, Nesis (1997) proposed that  G. japonicus be recommended as the valid scientific name for G. makko. Nesis (1997) also mentiond that some of the large individuals of G. makko, including the types found in the stomach contents of sperm whales might be spent females of Gonatus madokai.

Although systematic confusion is still unsolved, the holotype of G. makko is in good enough condition to compare the other species and has apparently smaller fins than G. madokai. A small possibility exists of G. japonicus being an immature female of G. makko, even though G. makko has precedence.

Diagnosis

A Gonatopsis with...

•  slender cylindrical mantle with thin wall.
  
•  long arms of 2/3 mantle length.
  
•  small fin, fine length = fin width.
  

Characteristics

1. Arms
   1. Arms thick, muscular, robust, very powerful in appearance.
   2. Arms almost equal in length, about 2/3 of mantle length, indicating 2,3,1,4.
      
   3. Arm webs not well developed except between the ventral arms.
   4. Armatures set in 4 rows and composed of hooks and suckers.
   5. Arms I-III have hooks in inner two rows and suckers in marginal rows.
   6. Arm IV has suckers in all 4 rows.
   7. Hooks very sharp with vestigal sucker-like structure proximally
      
      
2. Tentacle
   1. Tentacle completely absent.
      
      
3. Head
   1. Head as broad as the mantle openinig.
   2. Nuchal locking-cartilage elongated rectangular with rounded corners.
   3. Funnel locking-cartilage lanceolate, slightly curved with shallow groove.
   4. Dorsal funnel organ V-shaped; ventral organs small and ovoid.
      
      
4. Mantle
   1. Mantle subcylindrical, tapering gradually posteriorly to attenuated point.
   2. Mantle wall thin, soft to touch.
   3. No sculpture and color patterns present.
      
      
5. Fin
   1. Fins subrhomboidal with thinned margins.
   2. Fins one-third as long as mantle lenght.
      
   3. Fin width same as fin length.
      
      
6. Gladius
   1. Gladius slenderly penniform, about 1/15 broad as long.

Distribution

The distribution of Gonatopsis makko is confined to the Bering Sea, Sea of Japan and off northeastern Honshu, Japan.

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

Figure. Distribution of Gonatopsis makko Dark pink area indicates known range; light pink area indicates inferred range. Chart modified from Okutani, et al. (1988).

References

Ichisawa, K., Y. Kawakami, N. Honda & R. Kuranaga. 2006. A record of a gonatid squid Gonatopsis makko (Teuthoida: Gonatidae) captured near the Yamato Bank, central region of the Sea of Japan. Bulletin of Tottori Prefectural Museum, 43:13-15. (in Japanese)

Nesis, K. T. 1997. Gonatid squids in the subarctic North Pacific: Elology, biogeography, niche diversity and role in the exosystem. Advances in MarineBiology, 32:243-324.

Okutani, T. & T. Nemoto. 1964. Squids as the food of sperm whales in the Bering Sea and Alaskan Gulf. Scientific Reports of the Whales Research Institute, 18: 111-121.

Okutani, T., Y. Satake, S. Ohsmi & T. Kawakami. 1976. Squids eaten by sparm whales caught off Joban district, Japan, during January-Februaly, 1976. Bullletin of Tokai Regional Fisheries Reserach Laboratory, 87: 67-113.