Luteuthis O'Shea 1999

Introduction

Luteuthis spp. are very fragile, gelatinous, presumably pelagic cirrate octopods whose affinities are uncertain (see Nomenclature) The two species in this genus are known from only three specimens.

Brief diagnosis:

An opisthoteuthid ...

• with distinctive broad, W-shaped shell.
  
• with optic nerves passing through white body as a single bundle.

Full diagnosis (from Collins and Villanueva, 2006):

"Grimpoteuthids with moderate-sized fins, short cirri (<2% ML) and a bilobed digestive gland. Shell W-shaped with lateral wings tapering to acute, offset points. Radula well developed. Male accessory glands in linear sequence. Web supporting nodules absent." *

* Refers a diagnosis of the genus within their family Grimpoteuthidae which also includes the genera Grimpoteuthis and Cryptoteuthis.

Characteristics

1. Shell
   1. Shell W-shaped.
   2. Shell with basal shelf deflected beneath saddle.
   3. Shell with lateral wings keeled, in some species, inrolled margins.
   

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   Figure. Ventral and posterior views of shell of L. shuichi. Photograph from O'Shea and Lu, 2002.

2. Arms and web
   1. Sucker enlargement in males undetermined.
   2. Sucker apperature crenulate with tooth-like structures.
   3. First cirri between suckers 4 and 6.
   4. Cirri short; maximum length comparable to half of largest sucker diameter.
   5. Web nodules absent.
   

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   Figure. Side and oral view of cut suckers showing tooth-like structures of L. dentatus. Drawing from O'Shea, 1999.

3. Pigmentation
   1. No areolar spots.


4. Gills
   1. Gills with half-orange appearance.


5. Digestive system
   1. Intestine shorter than or approximately equal to esophagus (including crop) in length.
   2. Digestive gland bilobed.
   3. Radula present.
   

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   Figure. Side view of the digestive system of L. dentatus. Drawing from O'Shea, 1999.

6. Reproductive system
   1. Male with linear arrangement of accessory glands.
   2. Penis well developed.


7. Optic lobe
   1. Circular in cross-section
   2. Single optic bundle penetrates the white body.
   

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   Figure. Digestive system of L. dentatus. Drawing from O'Shea, 1999.

Comments

The two distinctive features of Luteuthis are the tooth-like structures on the suckers and the shape of the shell.

Nomenclature

The genus Luteuthis was established by O'Shea (1999) and placed in its own family, the Luteuthidae. O'Shea and Lu (2002) state that the family is distinguished by the following features:

• Presence of a radula.
• W-shaped shell.
• Suckers with tooth-like margins.
• Linear arrangement of accessory glands in the male.

The presence of a radula is now known be we widely distributed in Grimpoteuthis. The W-shaped shell is unusual but an intermediate condition is seen in Grimpoteuthis tuftsi).  The peculiar suckers appears to be a unique feature. The arrangement of accessory glands needs further evaluation. The arrangement of glands is unknown in many species and where known the clear arrangement of the parts and, indeed, their proper identification is often unclear.

O'Shea and Lu, 2002, placed this species to be in its own family, Luteuthidae. Collins and Villanueva (2006) placed it in the family Grimpoteuthidae.

References

O'Shea, S. 1999. The marine fauna of New Zealand: Octopoda (Mollusca: Cephalopoda). NIWA Biodiversity Memoir 112: 280pp.

O'Shea, S. and C. C. Lu. 2002. A New Species of Luteuthis (Mollusca: Cephalopoda: Cirroctopoda) from the South China Sea. Zoological Studies, 41: 119-126.