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Illicinae Posselt 1891

Illex Steenstrup 1880

Michael Vecchione and Richard E. Young
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taxon links [up-->]Illex oxygonius [up-->]Illex coindetii [up-->]Illex illecebrosus [down<--]Ommastrephidae Interpreting the tree
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Containing group: Ommastrephidae

Introduction

This subfamily, as currently recognized, contains only the genus Illex. These are commercially important species found in neritic waters of the North and South Atlantic (Roper et al., 1998). The number of species in the North Atlantic has been controversial, with the validity of I. oxygonius repeatedly questioned. Carlini et al. (2006) used molecular methods to confirm that three species are present in the North Atlantic. Since I. oxygonius  occupies waters where the distributions of I. illecebrosus and I. coindetii overlap, it could represent a hybrid of these species (Roper, et al., 1998).  Morphological identification of specimens, even mature males, can be quite difficult since all four species exhibit considerable intraspecific morphological variability; no single character will allow consistent identification of species (Roper, et al., 1998).

Brief diagnosis:

Ommastrephids with ... 

Characteristics


  1. Arms
    1. Either right or left ventral arm hectocotylized.
    2. Distal portion of hectocotylus without protective membranes.
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    Figure. Oral views of the distal region of the hectocotylus of Illex oxygonius. Top - Photograph by M. Vecchione. Bottom - Drawing from Roeleveld (1988). v - Ventral side.

  2. Tentacles
    1. Large, medial club suckers with smooth or bluntly crenulated inner rings.
    2. Dactylus of tentacular club with suckers in eight series.
    3. Carpal locking-apparatus absent.
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    Figure. Oral view of the dactylus of the tentacular club of Illex sp. Photograph by M. Vecchione.

  3. Head
    1. Funnel groove without foveola or side pockets.

  4. Funnel
    1. Funnel/mantle locking apparatus with simple inverted T-shape. 
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      Figure. Funnel (left) and mantle (right) components of the funnel/mantle locking apparatus of Illex illecebrosus, stained with methylene blue stain. Photographs by R. Young.

  5. Photophores
    1. Photophores absent.

  6. Comparison of species
      I. illecebrosus
    I. coindetii
    I. argentinus
    I. oxygonius
    Hectocotylus midsection with
    papillose, fringed flaps
     No  Yes  No  No
    Largest distal medial manal club-sucker dentition
    Smooth
    7-8 broad, flat teeth
    Smooth or few notches
    Smooth
    Longest arm (arm II or III)
    ~ 50% ML
    ~ 60% ML
    ~ 70% ML
    ~ 55% ML
    Length distal portion of hectocotylus
    ~ 22 % ML
    ~ 25 % ML
    ~ 50 % ML
    ~ 29 % ML
    Length proximal bare portion of hectocotylus
    ~ 10 % ML
    ~ 13 % ML
    ~ 10 % ML
    ~ 4 % ML

Behavior

All species of Illex appear to congregrate, at least on occasion, near the ocean floor and spend time sitting on the ocean floor. Videos of Illex swimming near the ocean floor can be seen here.

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Figure. Left - Group of Illex sp., swimming near the ocean floor at about 600 m. Right - Illex coindetii sitting on the ocean floor. ©

Distribution

Species of Illex are found only in the Atlantic Ocean -- Western Atlantic Ocean from equator to Iceland and from southern Brazil to Patagonia, and eastern Atlantic from 20°S to 60°N, including Mediterranean Sea. These species are generally confined to continental shelf and slope areas, or nearby oceanic waters, perhaps because of their habit of sitting on the bottom at depths of up to 1000 m.

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

Other Names for Illex Steenstrup 1880

References

Carlini, D.B., L.K. Kunkle, and M. Vecchione. 2006. A molecular systematic evaluation of the squid genus Illex (Cephalopoda: Ommastrephidae) in the North Atlantic Ocean and Mediterranean Sea. Molec. Phylog. Evol. 41:496-502.

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.

Title Illustrations
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Scientific Name Illex illecebrosus
Specimen Condition Fresh
View Dorsal
Size 270 mm ML
Image Use creative commons This media file is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0.
Copyright ©
About This Page


National Museum of Natural History, Washington, D. C. , USA


University of Hawaii, Honolulu, HI, USA

Page: Tree of Life Illicinae Posselt 1891. Illex Steenstrup 1880. Authored by Michael Vecchione and Richard E. Young. The TEXT of this page is licensed under the Creative Commons Attribution-NonCommercial License - Version 3.0. Note that images and other media featured on this page are each governed by their own license, and they may or may not be available for reuse. Click on an image or a media link to access the media data window, which provides the relevant licensing information. For the general terms and conditions of ToL material reuse and redistribution, please see the Tree of Life Copyright Policies.

Citing this page:

Vecchione, Michael and Richard E. Young. 2011. Illicinae Posselt 1891. Illex Steenstrup 1880. Version 13 January 2011 (under construction). http://tolweb.org/Illex/19940/2011.01.13 in The Tree of Life Web Project, http://tolweb.org/

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