Leachia dislocata Young, 1972

Introduction

Brief diagnosis:

A Leachia with ... 

• a complex tubercule, displaced medially, at anterior end of mantle strip.
• adult having completely sessile eyes.

Characteristics

1. Head
   
   1. Beaks: Descriptions can be found here: Lower beak; upper beak.
      
      
2. Mantle
   1. Length of cartilagenous strip 12-17% of ML.
   2. Complex tubercle at anterior end of strip displaced medially.
      

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      Figure. Ventral view of the anterior end of one cartilagenous strip on the mantle of L. dislocata, 136 mm GL. Drawing from Young, 1972.

3. Photophores
   1. On the adult eyeball, eight photophores comprise the outer series and the inner series (i.e., near the lens) consists of 7 photophores: two small photophores dorsal to the lens and five, three large organs alternate with two small ones, ventral to it.
      

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      Figure. Two views of the ocular photophores of L. dislocata, 143 mmm GL.

Comments

More details of the description can be found here.

The distinctive displaced tubercule on the cartilagenous strip is shared with Leachia pacifica.

Life History

The paralarva or the "pyrgopsis stage" has stalked eyes and few if any ocular photophores. The mature female has sessile eyes with a full compliment of photophores, relatively longer arms and photophores on the tips of arms III.

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Figure. Ventral views of two life-history stages of L. dislocata, off southern California. Top - Adult female, 145 mm GL. Bottom - Paralarva, 27 mm GL. Drawings from Young (1972).

Ocular photophores are gradually added through growth.

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Figure. Development of photophore compliment on eyes with growth in L. dislocata. Two views of each eye shown. A - 16 mm GL. B - 22 mm GL. C - 25 mm GL. D - 35 mm GL. E - 44 mm GL. F - 64 mm GL. G - 125 mm GL (holotype). H - 143 mm GL. Drawings from Young (1972).

Distribution

The type locality is 32°35'N, 118°06'W, off southern California in the eastern North Pacific. Also known from off the Pacific coast of Baja California at 27°45'N (Okutani, 1979).

References

Okutani, T. 1974. Epipelagic decapod cephalopods collected by micronekton tows during the EASTROPAC expeditions, 1967-1968 (systematic part). Bull. Tokai Reg. Fish. Res. Lab., 80: 29-118.

Voss, N. A. 1980. A generic revision of the Cranchiidae (Cephalopoda; Oegopsida). Bull. Mar. Sci. 30: 365-412.

Young, R. E. 1972. The systematics and areal distribution of pelagic cephalopods from the seas off Southern California. Smithson. Contr. Zool., 97: 1-159.