Planctoteuthis danae (Joubin 1931)

Introduction

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

Figure. Side view of P. danae, 45 mm ML, preserved, Gulf of California. Photograph by R. Young.

Planctoteuthis danae is one of the more sturdy members of the genus, and it is most easily recognized by its relatively large, muscular fins.

Diagnosis

• Fin length more than 50% of mantle length.

Characteristics

1. Arms
   1. Arms II each with two enlarged suckers in mid-arm.
   2. Arms IV each with 12-13 suckers.
      
      

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

      
      
      

      Figure. Oral view of P. danae, holotype, showing arm suckers. Top - Arrow points to enlarged suckers of arms II. Bottom - Arrows point to terminal suckers on arms IV. Photographs by R. Young.

2. Tentacular clubs
   1. Clubs bilaterally symmetrical and lack keels.
   2. Club length 12-18% of ML.
      
      

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

      
      

      Figure. Several views of a tentacular club of P. danae, holotype. Note that suckers at the base of the club have broader aperatures than remaining suckers. Photographs by R. Young.

3. Head
   
   1. Beaks: Descriptions can be found here: Lower beak; upper beak.
      
      
4. Funnel
   1. Antitragus of funnel locking-apparatus with two distinct lobes.
      

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

      

      Figure. Frontal view of the funnel locking-apparatus, P. danae, subadult, eastern Pacific. Photograph by R. Young.

5. Fins
   1. Fin length 52% of ML.

Comments

More details of the description of P. danae can be found here. 

Nomenclature

This species was originally placed in the genus Valbyteuthis Joubin, 1931, which was subsequently synonomized with Planctoteuthis (Young, 1991).

Life history

Paralarvae of P. danae are most easily distinguished from other doratopsis paralarvae in Hawaiian waters by:

1. The dorsal position of the oesophagus in the brachial pillar (see figure).
2. The small number of brachial pillar chambers (two).

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

Figure. Paralarvae of Planctoteuthis danae from the waters off Hawaii: Thumbnail - Ventral view of the two paralarvae showing relative sizes. Left - Side view of the head, 2.6 mm ML, showing the ventrally protruding eye, the dorsal position of the esophagus and the small number of chambers in the brachial pillar. Middle - Ventral and dorsal views, 8.4 mm ML. Right - Ventral and dorsal views, 22 mm ML. Scale bars are 1 mm. Drawings from Young, 1991.

Distribution

Vertical

In the eastern North Atlantic paralarvae are found mostly between 200 and 300 m (Clarke and Lu, 1974). Between about 10 and 15 mm ML they are found between 200 and 800 m and at larger sizes they are found at depths greater than 700 m during the day with some captures at depths of over 1000 m. In 1974 P. danae was in the genus Valbyteuthis which contained only two species, P. danae and P. oligobessa Young, 1972, both from the Pacific Ocean. The identification of the species upon which this vertical distribution is based needs confirmation. We know of no other records of P. danae in the Atlantic Ocean. The data could refer to P. lippula.

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

Figure. Vertical distribution graph based on opening/closing nets with tows at two localities, one at 11°N Lat. and the other at 18°N Lat., North Atlantic. Yellow - Day capture. Blue - Night capture. Bar length - fishing depth of net. Chart modified from Clarke and Lu, 1975 and Lu and Clarke, 1975.

Geographical

The type locality is the Gulf of Panama, tropical eastern Pacific Ocean. It has also been reported from off California and Hawaii (Young, 1972; 1978), off central Chile and the eastern Polynesian Islands (Nesis, 1982), and the eastern North Atlantic -see comments above- (Clarke and Lu, 1975 and Lu and Clarke, 1975).

References

Clarke, M. R. and C. C. Lu. 1975. Verical distribution of cephalopods at 18 N 25 W in the North Atlantic. Journal of the Marine Biological Association of the United Kingdom, 55 (1): 165-182.

Joubin, L. 1931. Notes preliminaires sur les cephalopodes des croiseires du “Dana” (1921-1922). Annales de l’Institut Oceanographique, 10: 169-211.

Lu, C. C. and M. R. Clarke, 1975. Vertical distribution of cephalopods at 11 N 20 W in the North Atlantic. Journal of the Marine Biological Association of the United Kingdom, 55 (2): 369-389.

Nesis, K. N. 1982. Abridged key to the cephalopod mollusks of the world's ocean. 385+ii pp. Light and Food Industry Publishing House, Moscow. (In Russian.). Translated into English by B. S. Levitov, ed. by L. A. Burgess (1987), Cephalopods of the world. T. F. H. Publications, Neptune City, NJ, 351pp.

Roper, C. F. E. and R. E. Young (1967). A review of the Valbyteuthidae and an evaluation of its relationship with the Chiroteuthidae. Proc. U.S. Nat. Mus., 123: 1-9.

Young, R. E. (1991). Chiroteuthid and related paralarvae from Hawaiian waters. Bull. Mar. Sci., 49: 162-185.