Under Construction

Taonius belone (Chun, 1906)

Richard E. Young
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Containing group: Taonius

Introduction

Taonius belone is the tropical Indo-Pacific congener of the temperate/boreal Pacific T. borealis. Nesis (1972) originally described two subspecies under the name T. borealis : T. b. borealis and T. b. pacifica. The latter was based largely on Sasaki's 1929 description of "T. pavo" much of which is reproduced below. However, Chun (1906, 1910) had described a juvenile species of the genus (T. belone) from the Indian Ocean and Nesis (1982/87) placed T. b. pacifica within the synonymy of T. belone. N. Voss (see Nomenclature under the Taonius genus page) is very familiar with this genus and supports this synonomy.

Brief diagnosis:

A Taonius with ...

 

Characteristics

  1. Arms
    1. Arms short; formula: 3>2=4>1.
    2. Protective membranes narrow except their proximal part, which are wide and connected together into an internal umbrella.
    3. Arm suckers biserial throughout, crowded distally; suckers number 21 pairs or more on each arm. Largest suckers about 8th pair.
    4. Larger suckers with 20-30, broad, closely set teeth around entire margin of ring; distal suckers with only 6-8 teeth; proximal suckers with teeth united appearing smooth except for few distal undulations.
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    Figure. Oral views of arm suckers of T. belone. Left - Arm III, sucker 20, 119 mm ML. Drawing from Voss (1963). Middle - Large arm sucker, 330 mm ML. Right - Distal arm sucker, 330 mm ML. Latter two drawings from Sasaki (1929).

  2. Tentacles
    1. Largest two (?) suckers of medial two series of club manus with one or two enlarged, hook-like teeth; smaller secondary teeth absent.
    2. Other enlarged suckers of medial series of club manus with two largest hook-like teeth more nearly equal in size; 4-5 smaller secondary teeth present.
    3. Suckers of marginal series of manus  laterally compressed, each with two elongate, incurved teeth on distal and pointed teeth on lateral margin of sucker ring.
    4. Tentacular stalk with two series of locking suckers on distal 2/3 to 3/4 of stalk. Indistinct carpal cluster at base of manus.
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    Figure. Oral view of the tentacular club of T. belone, 330 mm ML, showing enlargement of some suckers. Drawing from Sasaki (1929).

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    Figure. Oral views of club sucker rings of T. belone, Phillipine Islands. Drawing from Voss (1963).

  3. Head
    1. Beaks: Descriptions can be found here: Lower beak; upper beak.

  4. Mantle
    1. At funnel-mantle fusion, tubercules absent .
    2. Mantle skin smooth.

  5. Fins
    1. Fins elongate, lanceolate and subterminal; each fin at anterior insertion broadly separated from each other; fin length 44% of ML.
    2. Gladius extends beyond fins as axis of tail .

Comments

The above characteristics are taken from Sasaki, 1929 and Voss, 1963.

Life History

Paralarvae of T. belone from Hawaiian waters have been identified. they are distinctive among cranchiid paralarvae from these waters in the near lack of chromatophores.

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Figure. Paralarvae of T. belone, Hawaiian waters. Thumbnail (far left) - Illustration shows relative sizes of the two paralarvae. Left - Ventral view of a 4.9 mm ML paralarva. The dotted circle in indicates the position of the digestive gland. The adjacent inserts show (1) a side view of an eye and (2) a dorsal view of the fins. This paralarva has no chromatophores. Right - Ventral and dorsal views of a 14.5 mm ML paralarva. This paralarva has one chromatophore on the dorsal and one on the ventral surface of the head and a few chromatophores on the aboral surface of each tentacular club and one at the base of each tentacle but none on the mantle. Also note the small size of the tentacular club and the shape of the fins. The scale bars are 1 mm. Drawings by R. Young.

Young (1975) found that the structure of the eyes changed with the vertical distribution of this species as in Sandalops melancholicus. Although data were few, he found paralarvae with stalked, laterally compressed eyes, in the upper 400 m; juveniles from 50 to 140 mm ML were captured between 500 and 700 m with most taken between 600 and 650 m. At depths greater than 700 m the squid had hemispherical eyes.

Figure. Growth stages of Taonius belone showing changes in eye shape.
Drawings from Young (1975).

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    Figure. Ventral-oblique (left) and ventral (right) views of a tubular eye of a juvenile T. belone, off Hawaii. Photograph by R. Young.

    The laterally compressed eyes of paralarvae will reduce the size of a shadow cast by the opaque eyeballs under the highly directional downwelling daylight to aid in camouflage. In deeper waters where the intensity of downwelling daylight is reduced the upward looking tubular eye is more easily camouflaged with silvery mirrors on the sides and a photophore on the underside of the eye to match the weak downwelling light and, thereby, eliminate the eye shadow (= counterillumination). In deeper water yet, darkness allows the eye to assume a more normal shape that allows a broader visual field (Young, 1975).

Distribution

Geographical distribution

Type locality: Indian Ocean at 10°8'S, 97°14'E.

Found off southern Japan, Philippine Islands, Hawaiiiian Islands, central equatorial Pacific and, presumably throughout the tropical and subtropical Indo-Pacific, but details are poorly known. 

Vertical distribution

Off Hawaii T. belone appears to exhibit ontogenetic descent and not to undergo diel vertical migration (Young, 1975). 

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Figure. Vertical distribution of T. belone, Hawaiian waters. Captures were made with both open and opening/closing trawls. Bars - fishing depth-range of opening/closing trawl. Circle - Modal fishing depth for either trawl. Blue-filled circles - Night captures. Yellow-filled circles - Day capture. Chart modified from Young (1975).

Other Names for Taonius belone (Chun, 1906)

References

Sasaki, M. 1929. A Monograph of the Dibranchiate Cephalopods of the Japanese and Adjacent Waters. Journal of the College of Agriculture, Hokkaido Imperial University, 20(supplement):357 pages.

Voss, G. L. 1963. Cephalopoda of the Philippine Islands. Bull. U. S. Nat. Mus., 234: 1-180.

Title Illustrations
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Scientific Name Taonius belone
Location Near Koshiki Island, Kiushiu, Japan
Reference Sasaki, M. 1929. A Monograph of the Dibranchiate Cephalopods of the Japanese and Adjacent Waters. Journal of the College of Agriculture, Hokkaido Imperial University, 20(supplement):357 pages.
View Ventral
Size 330 mm
Collection USNM 332946
Type Holotype
About This Page


University of Hawaii, Honolulu, HI, USA

Correspondence regarding this page should be directed to Richard E. Young at

Page: Tree of Life Taonius belone (Chun, 1906). Authored by 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:

Young, Richard E. 2014. Taonius belone (Chun, 1906). Version 21 January 2014 (under construction). http://tolweb.org/Taonius_belone/120159/2014.01.21 in The Tree of Life Web Project, http://tolweb.org/

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