Mastigoteuthis hjorti (Chun, 1913)

Introduction

M. hjorti was originally described from five badly damaged specimens from the North Atlantic, then redescribed by Rancurel (1973) from three squid from the Gulf of Guinea. The species is distinctive and widely distributed but uncertainty exists on the taxonomic status of populations in other oceans.

Diagnosis

A Mastigoteuthis ...

• with two photophores on each eyeball.
• with very large fins (length ca 90% of ML).

Characteristics

1. Funnel
1. Funnel locking-apparatus with oval, slightly curved depression, posterolateral sides protude; without tragus or antitragus. Depression undercuts posterior margin.
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Figure. Funnel/mantle locking-apparatus of M. hjorti. Left - Funnel component uppermost; mantle component below on mantle folded back. Drawing from Rancurel (1973). Left two photographs - Funnel and mantle components of the locking apparatus, equatorial ?? Pacific. Right two photographs - Funnel and mantle components of the locking apparatus, 73 mm ML, eastern North Atlantic, 17°24'N, 22°57'W, NMNH 815489. Structures in photographs stained with methylene blue. Photographs by R. Young.

2. Mantle and Skin
1. Large tubercules cover mantle, head, funnel and aboral surface of arms in subadults (tubercules are often lost during capture).
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Figure. Left - Lateral view of head of M. hjorti showing tubercules and olfactory organ, 48 mm ML, western North Atlantic. Also visible are two lines on the head of the lateral-line analogue of cephalopods. Photograph by R. Young. Right - Scanning electron micrograph of mantle tubercles of M. hjorti, 93 mm ML, South Africa at 80°S, 05°E. Scale 0.1 mm. Photograph from Roper and Lu (1990).

3. Fins
1. Fins large, nearly the full length of the mantle. (see title photograph).
4. Photophores
1. Two large circular photophores on ventral surface of eyeball; no other photophores present.
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Figure. Ventral view of damaged eye of a fresh M. hjorti, western North Atlantic. Arrows point to photophores. Photograph by M. Vecchione.

Comments

More information on the description of M. hjorti can be found here.

M. hjorti bears resemblance to M. cordiformis in the presence of large fins, skin tubercules, lack of a pocket between the bridles and the large trabeculate protective membranes on the tentacular clubs but differs in the presence of ocular photophores among other features.

Life History

Vecchione, et al. (2001) described a 6 mm ML paralarvae which they assummed belonged to M. hjorti on the basis of a single large photophore on each eyeball. They described the paralarva as follows:

Mantle narrow, inserts on anterior end of fins. Fins ca. 25% of ML (excluding tail). Long, spike-like tail, nearly 3 times fin length. Skin mostly missing but fragments with scattered tubercules present. One light organ on ventral surface of each eye. Arm formula: II>I>IV>>III (arms III are minute buds). Tentacles long, thick, about 4 times length of arms II. Clubs with about 54 small suckers in 2 series proximally grading to 6 along "manus." Suckers end abruptly; tip with sucker anlagen.

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Figure. Paralarva of M. hjorti. A - dorsal view of paralarva, 6.0 mm ML, USNM 730521. B - oral view of tentacular club, same specimen. C - ventral view of eye with ocular light organ, same specimen. D - oral view of brachial crown, same specimen; note small arms III. Drawings from Vecchione, et al. (2001).

Distribution

Type locality: North Atlantic at 36°N, 40°W; 32°N, 33°W; 36°05'N, 43°58'W. The species is also known from the central Pacific (pers. obs.), off South Africa (Roper and Lu, 1990) and the Indian Ocean (Nesis, 1987).

References

Chun, C. 1913. Cephalopoda. Report on the Scientific Results of the "Michael Sars" North Atlantic Deep-sea Expedition 1910, 3(1). Reprinted by Bergen Museum, 1933, 21 pages.

Nesis, K. N. 1982/87. 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.

Rancurel, P. 1973. Mastigoteuthis hjorti Chun 1913 description de trois ?chantillons proventant du Golfe de Guin?e. Cah. O.R.S.T.O.M., ser. Oc?anogr., 11: 27-32.

Roper, C.F.E. and C.C. Lu 1990. Comparative morphology and function of dermal structures in oceanic squids (Cephalopoda). Smithson. Contr. Zool., No. 493: 1-40.

Vecchione, M., C. F. E. Roper, M. J. Sweeney and C. C. Lu. 2001. Distribution, relative abundance and developmental morphology of paralarval cephalopods in the western north Atlantic Ocean. NOAA Technical Report NMFS 152: 1-58.