Under Construction

Containing group: Onykia

Introduction

Wakabayashi et al. (2007) found a paralarval Onykia near Hawaii (28°30'N 155°W at a surface temperature of 23.3°C) that could not be assigned to any know species of the genus from the North Pacific based on molecular analysis of the COI gene. Therefore, we suspect that Onykia sp. A, found commonly in waters around the main Hawaiian Islands but known primarily from paralarvae, is a new species. A nearly mature female taken from the stomach of a sword fish with a small size further supports this possibility.

Brief diagnosis:

An Onykia with ...

• small maximum size (?)
• irregular warts on mantle (?)
  

Characteristics

The following information is from the nearly mature female (272 mm ML, see title photograph) taken, partly digested, from the stomach of a swordfish.

1. Arms
   1. Arm tips very attenuate.
      
2. Tentacles
   1. Right club with about 25-26 hooks, left club with about 22 hooks.
3. Head
   1. Beaks: Descriptions can be found here: Lower beak; upper beak.
   2. Funnel groove with inverse Y-shaped ridge.
      
4. Mantle
   1. Mantle appears to have been covered with round/irregular warts.
5. Fins
   
   1. Fins sagittate; extend to posterior tip of tail.
      
6. Viscera
   1. Gladius rostrum of 272 mm ML female: 45 mm long, measured from ventral edge of conus.
   2. Irregular shape in cross-section.
      
      

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

      
      

      Figure. Onykia sp. A, distal part of rostrum. Left - Side view. Right - Cross section. Photographs by R. Young.

   3. Nidamental and oviducal glands well developed.
      
      
7. Measurements:

   Female	mm
   Mantle length	272
   Head width	34
   Funnel lock, lenght	25
   Mantle lock, length	45
   Arm I, length	152
   Arm II, length	170
   Arm III, length	178
   Arm IV, length	188
   Tentacle length	400
   Club length	68
   Fin length*	145
   Fin width	150

   *Measured to tip of tail.

Comments

Onykia sp. A is similar to the the warm water O. robsoni/O.carriboea but cannot be clearly separated from them at present.

Life History

The paralarvae of Onykia sp. A  (Figs. A-C below) are easily distinguished from other squid paralarvae in Hawaiian waters: They are broad and have a characteristic line of large dorsal mantle chromatophores whose widths generally increase posteriorly. Small paralarvae often are observed in preserved samples with the head mostly withdrawn into the mantle cavity as shown in Fig. A.

Distribution

Onykia sp. A is known only from the tropical/subtropical central North Pacific.

References

Wakabayashi, T., T. Kubodera, M. Sakai, T. Ichii, and S. Chow. 2007. Molecular evidence for synonymy of the genera Moroteuthis and Onykia and identification of their paralarvae from northern Hawaiian waters. Journal of the Marine Biological Association of the UK, 87: 959-965.