Echinoteuthis tyroi (Salcedo-Vargas, 1997)

Introduction

Diagnosis

A mastigoteuthid ...

• with expanded clubs in paralarval stage.
• with tubercules in paralarval stage.

Characteristics

1. Arms
1. Sucker dentition not examined.


2. Tentacles
   1. Tentacle stalk short, thicker than arms IV.
   2. Club flattened on oral surface and expanded.
   3. Club suckers in 47 rows with 4-9 series across club.
   4. Tip of club narrow and elongate, without suckers.
   5. Sucker dentition not examined.
   

   Click on an image to view larger version & data in a new window

   

   Figure. Aboral and oral views of tentacular clubs. Drawings from Salcedo-Vargas (1997).

3. Head
   
   1. Funnel pocket unknown.
      
      
4. Funnel
   1. Funnel locking- apparatus groove with simple structure lacking tragus or antitragus.
   

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   Figure. Ventral view of funnel locking-apparatus. Drawing from Salcedo-Vargas (1997)

5. Mantle
   1. Transparent, cartilaginous, spiny-like tricuspid tubercules present on mantle and most other skin.


6. Fins
   1. Fin longer than wide.
   2. Tail extends 20% of fin length.


7. Photophores
   1. Photophores absent.


8. Pigmentation
   1. Aboral surface of tentacle club and stalk with transverse pigment bands.
   2. Large chromatophores on both sides of head and at base of armature.
   3. Small chromatophores around anterior edge of mantle.


9. Measurements

   Source	Salcedo-Vargas, 1997
   Sex	?
   Mantle length	15
   Mantle width	3.5
   Head length	3.5
   Head width	2.5
   Fin length	8
   Fin width	12
   Arm I, length	1.2
   Arm II, length	1.8
   Arm III, length	1.2
   Arm IV, length	2.5
   Tentacle length	6
   Club length	3.5
   Eye diameter / Lens diam.	1.3 / 0.8

Comments

This paralarva is unlike any other described (although few species have described paralarvae) and is especially distinctive in having expanded tentacular clubs. The only species of mastigoteuthid that has slightly expanded tentacle clubs as a subadult is Idioteuthis cordiformis but this species is not known from the Indian Ocean.

Distribution

Type locality: Indian Ocean off the coast of Somalia at ca. 08.1°N, 56.1°E, 212 m depth. This species is known only from the type specimen.

References

Salcedo-Vargas, M. A. 1997. Cephalopods from the Netherlands Indian Ocean Programme (NIOP) - II. Mastigoteuthid lineage and related forms. Beaufortia, 47: 91-108.