Magnapinna atlantica Vecchione and Young 2006

Introduction

Magnapinna atlantica (formerly known as Magnapinna sp. A on this page) is based on two specimens taken from the North Atlantic.  The holotype (US National Museum of Natural History cat. no. USNM 1086800), 59 mm ML, immature female, was captured in the Gulf of Mexico at 27°09’N, 86°07’W on 16 Sept., 1995. It was captured intact with damage only to the tips of the appendages. The paratype (Natural History Museum, London, cat. no. BMNH 20060134) 53 mm ML, immature male, was captured over the mid-Atlantic Ridge near the Azores at 37°14'N. 32°18'W on June 21, 1997.

Diagnosis

A magnapinnid with:

• Tentacle bases narrower than adjacent arm bases.
• Proximal tentacle without suckers but with glandular structures.
• Pigment mostly in functional chromatophores

Characteristics

1. Arms
1. Arms short, thick, weakly muscled and decreasing abruptly in diameter distally to form sucker-bearing filaments (mostly lost due to damage)
2. Proximal-arms with suckers in two series (except at tips in some proximal-arms), ocasionally appearing slightly irregular.
   
   
2. Tentacles
1. Proximal-tentacles more slender than arms IV.
2. Proximal- tentacles short, thin and without suckers; distal-tentacles (filaments) very narrow and bearing small suckers mostly around 0.08 mm in diameter.
3. Distal third of proximal-tentacle with large, apparently glandular, lobes.

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


Figure. Left - Oral view of the brachial crown of M. atlantica, holotype. Right - Oral view of the left proximal tentacle and arm IV of M. atlantica, holotype, showing their relative thicknesses and the glandular regions of the proximal tentacle (yellowish tint). The distal tentacle and arm are missing. Note the broad lateral membrane on arm IV. Photographs by R. Young.

3. Fins and tail
1. Fins extremely large, about 90% of the mantle length.
2. Fins appear not to have been drawn-out into V-shaped point.
3. Tail presently a bare gladius with tip missing; extends at least 4 mm beyond fins.

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


Figure. Dorsal view of the posterior half of the fins of M. atlantica showing fin shape and the short gladius extending beyond the fins.

4. Pigmentation
1. Head, mantle, funnel, collars and fins with numerous scattered chromatophores.

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


Figure. Dorsal view of a portion of the fins of M. atlantica, holotype, showing large chromatophores.

Comments

This description is based on the holotype.  More details of the holotype's description can be found here. The paratype is a smaller specimen (53 mm ML) and in less perfect condition. Information on the paratype can be found here.

M. atlantica differs greatly from M. pacifica in the much thinner tentacles, the lack of suckers on the proximal tentacles, the presence of large, glandular regions on the proximal tentacles, two sucker series on the arms rather than three to four and numerous other features. These differences are great enough to suggest that they may belong in separate genera. The thin, bare proximal-tentacles are shared with the other Atlantic species.

References

Fischer, H. and L. Joubin. 1907. Expéditions scientifiques du TRAVAILLEUR et du TALISMAN. Céphalopodes, 8: 313-353.

Hardy, A. 1956. The Open Sea. Fisher, J., J. Gilmour, J. Huxley, M. Davies, and E. Hosking, Eds., Collins, London, 1956.

M. Vecchione, R.E. Young, A. Guerra, D.J. Lindsay, D.A. Clague, J.M. Bernhard, W.W. Sager, A.F. Gonzalez, F.J. Rocha, and M. Segonzac. 2001. Worldwide observations of remarkable deep-sea squids. Science, 294: 2505-2506.

Vecchione, M. and R. E. Young. 2006. The squid family Magnapinnidae (Mollusca; Cephalopoda) in the North Atlantic with a description of Magnapinna atlantica, n. sp.. Proc. Biol. Soc. Wash. 119 (3): 365-372.