Illex oxygonius Roper, Lu & Mangold 1969

Introduction

Characteristics

1. Arms
   1. Normal (non-hectocotylized) arms
      
      

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      Figure. Oral view of arm III of I. oxygonius, holotype, 207 mm ML. Drawing from Roper, et al. (1969).

       

      

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      Figure. Oral view of large arm-sucker-rings of I. oxygonius, hologype, 207 mm ML.  Drawing from Roper, et al. (1969).

   2. Hectocotylus (either left or right arm IV)
      

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      Figure. Oral view of the distal end of the hectocotylus of I. oxygonius, holotype, 207 mm ML. Drawing from Roper, et al. (1969).

      1. Hectocotylized arm longer and more robust than opposite arm in fully mature animals.
      2. Distal hectocotylized portion of arm IV (HA3) moderately long, about 29% (24%-32%) of total arm length; 3 knobs and 2 slightly flattened papillae proximal to well-developed lamellae in dorsal row.
         
      3. Basal portion (HAb) of hectocotylized arm 4% of total arm length.
      4. Proximal portion (HA1) with 7 pairs of normal suckers.
      5. Middle portion (HA2) with sucker diameters reduced in size by about 1/4 on both rows; oral surface of arm constricted slightly between HA1 and HA2, but with no distinct reduction of arm musculature between normal and reduced sucker areas; rows normally separated; trabeculae not modified as fringed lobes.
         
      

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      Figure. Generalized diagram of an Illex hectocotylus defining the terminology used. Drawing modified from Roper, et al., 1998.

2. Tentacles
   1. Club-sucker rings of largest distal medial manal suckers smooth, without crenulations or notches.
      
      

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      Figure. Oral view of the tentacular club of I. oxygonius, holotype, 2007 mm ML.  Drawing from Roper, et al. (1969).

      

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      Figure. Oral view of a  sucker ring of a large, medial manal sucker from the midregion of the tentacular club of I. oxygonius, holotype, 207 mm ML. Drawing from Roper, et al. (1969).

3. Head
   1. Head-width index high, 20.7 (19-23) in mature males, 17.8.
   2. Beaks: Descriptions and photographs can be found here: Lower beak; upper beak.
      
      

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      Figure. Side view of the upper (left) and lower beak (right) of I. oxygonius, paratype, 205 mm ML, male.  Drawing from Roper, et al. (1969).

4. Funnel
   1. Funnel/mantle locking-apparatus
      
      

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      Figure. Frontal views of the funnel (left) and mantle components (right) of the funnel/mantle locking-apparatus of I. oxygonius, holotype, 207 mm ML. Drawing from Roper, et al. (1969).

5. Gladius:
   

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   Figure. Ventral view of the gladius of I. oxygonius, paratype, 176 mm ML, male. Drawing from Roper, et al. (1969).

6. Fins
   1. "Fin angle in mature males acute, 25°-35°, occasionally 40°; fin width equal to fin length" Roper, et al., (1998)
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7. Reproductive structures
   1. Spermatophore: "Spermatophore cone at oral end of cement body, funnel-shaped, with sides equal, broadly triangular in outline; oral tube relatively broad; aboral neck moderately short, narrow" (Roper, et al., (1998).
      
      

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      Figure. View of a spermatophore (center) of I. oxygonius showing an enlargement of the oral end (top) and the central region (bottom). Drawing from Roper, et al. (1969).

Life History

Spawning grounds, season, eggs, and paralarvae are unknown at present. Food is also unknown, but presumed to be crustaceans and fishes.

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Figure. Ventral view of the cut-open mantle cavity of I. oxygonius. The nidamental glands are very large. White spermatangia are attached to the mantle walls and near an oviduct opening. Photograph by M. Vecchione.

Distribution

Type locality - Western North Atlantic off Key West, Florida at 24°13'N, 81°58'W.

Geographical distribution. I. oxygonius is found only in the western North Atlantic from off New Jersey (about 40°N) south to the Straits of Florida and the Gulf of Mexico but limits not well defined (Roper et al., 1998).

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Figure. Distribution chart of all four species of Illex; modified from Roper et al. (1998).

References

Roper, C.F.E., C.C. Lu, and K. Mangold. 1969. A New Species of Illex from the Western Atlantic and Distributional Aspects of Other Illex Species (Cephalopoda: Oegopsida). Proceedings of the Biological Society of Washington, 82:295-322.

Roper, C.F.E., C. C. Lu, and M. Vecchione. 1998. Systematics and distribution of Illex species; a revision (Cephalopoda, Ommastrephidae). In: Voss, N.A., et al. (eds.) Systematics and Biogeography of Cephalopods. Smithson. Contr. Zool. 586:405-423.