Eogonatus tinro Nesis, 1972

Introduction

Eogonatus tinro was first described but not named by Fields and Gauley (1971) then described and named by Nesis (1972). The paralarval, early juvenile and mature adult stages are not known. E. tinro is uncommon and although generally thought to be a small species, may reach a rather large size (Katugin, personal communication).

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Figure. Ventral and side views of E. tinro, ca. 90 mm ML. Note the very large eyes, small tentacles and long tail. ©

Brief diagnosis:

A gonatid ...

• without hooks on tentacular club.
• with 2-3 small ridges and grooves, and associated suckers and knobs, in proximal (carpal) locking-apparatus of tentacular club.

Characteristics

1. Arms
1. Hooks in medial two armature series on arms I-III.
   
   
2. Tentacles
   1. Tentacles present in subadults.
   2. Tentacular club without hooks.
   3. Suckers of tentacular club in numerous irregular series; suckers about equal in size.
   4. Proximal locking-apparatus of club with suckers and knobs medial to 2-3 small ridges and grooves.
   

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   Figure. Oral view of the tentacle of E. tinro. Drawing from Nesis (1972).

   

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   Figure. Oral view of the tentacular club of E. tinro, 65 mm ML, 45°07'N, 162°53'E. Drawing from Fields and Gauley (1971).
   

3. Head
1. Beaks. Descriptions can be found here: Lower beak; upper beak. See also this site.
   
2. Radula with teeth in 5 series.
   
   
4. Mantle
1. Mantle tissue flabby.
   
   
5. Fins
1. Fins sagittate, drawn out posteriorly into a short tail.
   
   
6. Photophores
1. Photophores absent.

Nomenclature

Distribution

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Figure. Distribution of E. tinro Dark pink area indicates known range; light pink area indicates inferred range. Chart modified from Okutani, et al. (1988). 

Other Names for Eogonatus tinro Nesis, 1972

• Eogonatus Nesis, 1972

References

Fields, W. G. and V. A. Gauley. 1971. Preliminary description of an unusual gonatid squid (Cephalopoda: Oegopsida) from the North Pacific. Jour. Fish. Res Bd Canada, 28:1796-1801.

Katugin, O. N., G. A. Shevtsov and M. A. Zuev. 2010. The morphology and biology of Gonatus tinro and Gonatopsis okutani (Teuthida: Gonatidae) indicate that they are conspecific. ICES Journal of Marine Science, 67: 1464–1477.

Nesis, K.N. 1972. Two New Species of Gonatid Squids from the North Pacific. Zoologichesky Zhurnal, 51(9): 1300-1307.

Okutani, T., T. Kubodera and K. Jefferts. 1983. Diversity, distribution and ecology of gonatid squids in the subarctic Pacific: A review. Bull. Ocean Res. Inst., Univ. Tokyo, No. 26 (1):150-192.