Stoloteuthis leucoptera (Verrill 1878)

Introduction

Stoloteuthis leucoptera, the type and the best known species of the genus, is very common throughout the year in the Gulf of Maine, U.S.A., at depths of 175 to 340 m. Only a few specimens have been taken on the outer shelf and slope south of Cape Cod, although it is found as far south as the Straits of Florida. It has also been reported from the Eastern Atlantic. This species, which reaches 25 mm ML, can be distinguished easily from all other neritic sepiolids in the western North Atlantic by the large ventral shield of the mantle characteristic of all members of the Heteroteuthinae. Note the dramatic blue fringe to the shield in the title photograph and the silvery band of tissue around the mantle.

Brief diagnosis:

A Stoloteuthis with...

• Narrow head-mantle fusion.
• glandular structures on dorsal and ventral borders of arms I in males. 

Characteristics

1. Arms (from Villanueva and Sánchez, 1993)
   1. Aboral keel well developed on arms III.
   2. Arms with 2 series of globular suckers except for 3-4 series at tips of arms IV in males.
   3. Males:
      
      1. Arms II with 1 or 2 (rarely 3) enlarged suckers at location of suckers 10-12.
      2. All suckers on arms II and III (at least) enlarged relative to females.
         
      3. Arms I with "cushion-like lateral membranes" on basal 2/3rds of arms.
      4. "Transverse [glandular] bundles of white finger-shaped structures 1.52 mm long by 0.38 mm wide adjacent to these membranes on arms I on both dorsal and ventral sides."
         
         

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         Figure. Oral view of the brachial crown of S. leucoptera. Left - Male, 15.6 mm ML, eastern South Atlantic off Nambia, Africa. Drawing from Villanueva and Sánchez (1993). Right - Male, 22 mm ML, preserved, western North Atlantic off USA. Photograph by R. Young.

   4. Females:
      
      1. Arms not modified in females.
         

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         Figure. Oral view of the brachial crown of S. leucoptera. Left - Female, 14.8 mm ML, eastern South Atlantic off Nambia, Africa. Drawing from Villanueva and Sánchez (1993). Right - Female, 22 mm ML, preserved, western North Atlantic off USA. Photograph by R. Young.

2. Tentacles
   1. Tentacle organ adjacent to or barely overlapping sucker-bearing club.
   2. Proximal suckers large, followed by small suckers then gradually larger suckers distally.
      

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      Figure. Oral view of the tentacular club of S. leucoptera, female, 22 mm ML, preserved, western North Atlantic off USA. Photograph by R. Young.

3. Funnel
   1. Funnel/mantle locking-apparatus with straight, simple groove in funnel component and straight, low ridge in mantle component.
      

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      Figure. Funnel/mantle locking-apparatus of S. leucoptera, 43°02'N, 69°04'W, NMNH 816246, left side of images is anterior. Top - Side-oblique view of the mantle component. Bottom - Frontal view of the funnel component. Photographs by M. Vecchione.

4. Mantle  (from Villanueva and Sánchez, 1993)
   1. Mantle dorsally fused to head by narrow commisure.
   2. Ventral mantle shield length nearly equal to ventral mantle length.
      
   3. Mantle bulges dorsally.
   4. Anterior margin of ventral mantle slightly indented in midline.
      

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      Figure. Dorsal and/or ventral views of S. leucoptera. Left - Male, 15.6 mm ML, eastern South Atlantic off Nambia, Africa. Drawing from Villanueva and Sánchez (1993). Right - Male, 19 mm ML, preserved, western North Atlantic off USA. Photograph by R. Young.

      

      Figure. Side view of S. leucoptera, Male, 15.6 mm ML, eastern South Atlantic off Nambia, Africa, showing dorsal hump of mantle. Drawing from from Villanueva and Sánchez (1993).

5. Fins
   1. Posterior fin lobes broadly rounded.
      

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      Figure. Dorsal view of folded left fin of S. leucoptera, Male, 23 mm ML, preserved, western North Atlantic off USA, showing shape of posterior fin lobe (arrow). Photograph by R. Young.

6. Photophores
   1. Large, visceral photophore with pair of papillae located near midline. Internal to each papilla are two ducts that penetrate the "lens" but are invisible laterally.
      

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      Figure. Posteroventral view of the visceral photophore of S. leucoptera. Note the position and appearance of the ventral pores. Photograph by R. Young.

7. Pigmentation
   1. Value uncertain. At present no known specific characters are associated with pigmentation. However, we suspect this will be important in the future especially in separating closely related species such as S. maoria.
      

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      Figure. S. leucoptera, preserved, mature female, 20 mm ML, showing pigmentation of the funnel and tentacle. Left - Ventral view of the head and mantle cavity. Right - Ventrolateral view of the head and funnel. Photographs by R. Young.

8. Viscera
   1. Large, gelatinous masses, similar in appearance to swollen funnel organs, present in both sexes on either side of the mantle cavity between gills and funnel organ.
      

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      Figure. Ventral view of the mantle cavity of S. leucoptera, mature male, 22 mm ML. Note the gelatinous tissue which is damaged on the animal's right side. Photograph by R. Young.

Comments

The above description is taken from specimens captured off NE USA and from the paper of Villaneueva and Sanchez (1993) from off Namibia.

Comparison of S. leucoptera with other Stoloteuthis species can be found on the Stoloteuthis page.

Life History

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Figure. Dorsal and ventral views of portions of S. leucoptera showing implantation of spermatangia on the left side of the head. Photographs by R. Young.

Distribution

Type locality: Gulf of Maine, 48 km east from Cape Ann, Atlantic Ocean. Known as far south along USA coast the Straits of Florida (Cairns, 1976). Also known from the N.E. Atlantic at 47°N, 5.8°W (Degner, 1925), Mediterranean Sea (Villanueva and Sánchez, 1993), and off Namibia (Villanueva and Sánchez, 1993).

References

Cairns, S. D. 1976. Biological results of the University of Miami deep-sea expeditions. 118. Cephalopods collected in the Straits of Florida by the R/V GERDA. Bull. Mar. Sci., 26: 233-272.

Degner, E. 1925. Cephalopoda. Report on the Danish Oceanographical Expeditions 1908-10 to the Mediterranean and Adjacent Seas, 2(9):1-94.

Villaneueva, R. and P. Sánchez. 1993. Cephalopods of the Benguela Current off Namibia: new additions and considerations in the genus Lycoteuthis. Journal of Natural History, 27: 15-46.