Family PSYCHROTEUTHIDAE Thiele, 1920

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• PSYCHROTEUTHIDAE Thiele, J. 1920. Die Cephalopoden der deutschen Südpolar-Expedition 1901–1903. Deutsche Südpolar Expedition 16(Zool. 8): 433- 465 4 pls.

  Type genus:

   Psychroteuthis Thiele, 1920.

Introduction

Members of the family Psychroteuthidae Thiele, 1921 are medium to large sized oceanic squid, with a muscular mantle and rhomboidal fins. They are common in Antarctic waters. The family consists of two species, Psychroteuthis glacialis Thiele, 1921 and an undescribed species (Roper et al. 1969); Iwai (1956) reported another species from the stomach contents of a sperm whale off Bonin Island (see Nesis 1987). In Australian waters only Psychroteuthis glacialis is known, from the Prydz Bay area (Lu & Williams 1994).

In the Prydz Bay area, two distinct size classes of Psychroteuthis glacialis, 4–18 mm mantle length (ML) and 90–210 mm ML with the modes at 13 mm and 135 mm, have been captured (Lu & Williams 1994). Piatkowski et al. (1990) reported capturing, at the same time of the year, specimens belonging to a distinct size class of 100–180 mm ML (mode 130 mm ML) and there large specimens of 330–370 mm ML from the Weddell Sea. These data indicate three distinct year classes may have existed (Lu & Williams 1994). Statolith increments in three specimens of Psychroteuthis glacialis indicate large variations (Jackson & Lu 1994).

The vertical distribution of this species is poorly known, but recent data from Prydz Bay suggested strong ontogenetic descent with the small individuals living at shallow depths and the subadults living on or near the bottom (Lu & Williams 1994). The species feeds on a variety of food, including the Antarctic krill, Euphausia superba, a fish, Pleuragramma antarcticum, and conspecific squid (Lu & Williams 1994). They have been found in the stomach of the emperor penguin, Aptenodytes forsteri (Gales et al. 1990), southern elephant seals (Klages 1996), and many species of seabirds from the Antarctic (Croxall & Pince 1996).

Diagnosis

Psychroteuthids are medium and large squids with the mantle muscular. The fins are rhomboidal with ends attenuate. The arms are equipped with 2 rows of suckers. The wide tentacular club is equipped with 4 rows of unequal-sized suckers in the proximal part and 5 to 7 rows of small suckers in the distal part. The tentacular stalk is equipped with a fixing apparatus. The funnel locking cartilage is simple, slightly bent, and the buccal connectives attach to the dorsal borders of the ventral arms.

General References

Clarke, M.R. 1966. A review of the systematics and ecology of oceanic squids. Advances in Marine Biology 4: 91-300

Croxall, J.P. & Prince, P.A. 1996. Cephalopods as prey. I. Seabirds. Philosophical Transactions of the Royal Society of London B 351: 1023-1043

Gales, N.J., Klages, N.T.W., Williams, R. & Woehler, E.J. 1990. The diet of the emperor penguin, Aptenodytes forsteri, in Amanda Bay, Princess Elizabeth Land, Antarctica. Antarctic Science 2(1): 23-28

Iwai, E. 1956. Description of unidentified species of dibranchiate cephalopods, I–II. Science Reports of the Whales Research Institute 11: 139-161

Jackson, G.D. & Lu, C.C. 1994. Statolith microstructure of seven species of antarctic squid captured in Prydz Bay, Antarctica. Antarctic Science 6(2): 195-200

Klages, N.T.W. 1996. Cephalopods as prey. II. Seals. Philosophical Transactions of the Royal Society of London B 351: 1045-1052

Lu, C.C. & Williams, R. 1994. Contribution to the biology of squid in the Prydz Bay region, Antarctica. Antarctic Science 6(2): 223-229

Nesis, K.N. 1987. Cephalopods of the World. Neptune City, N.J. : T.F.H. Publications, Inc., Ltd 351 pp.

Piatokowski, U., While, M. & Dimmler, W. 1990. Micronekton of the Weddell Sea: distribution and abundance. pp. 73-81 in Arntz, W., Ernst, W. & Hempel, I. The expedition ANTARKTIS VII/4 (Epos leg 3) and VII/5 of RV "Polarstern" in 1989. Berichte zur Polarforschung 68

Roper, C.F.E., Young, R.E. & Voss, G.L. 1969. An illustrated key to the families of the order Teuthoidea (Cephalopoda). Smithsonian Contributions to Zoology No. 13: 1-32

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