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Leachia Lesueur, 1821

Richard E. Young and Katharina M. Mangold (1922-2003)

Six of the 14 nominal species of Leachia are considered valid by Voss, et al. (1992). These authors suggest that ll species exist in the genus, 5 of which are undescribed.

Containing group: Cranchiinae

Introduction

Members of this genus are easily recognized by the two straight cartinagenous, tubercular strips on the mantle that arise from each point of funnel-mantle fusion, the slender, tapering mantle and the terminal fins with a combined oval shape. The species of the genus, however, are not easily recognized. Many names exist in the literature and most have poor descriptions associated with them and are based on paralarvae. At present, geographical location is one of the most important characteristics used in identification. The type localities of the named species are:

Atlantic Ocean
Indian Ocean
Pacific Ocean

Diagnosis

A cranchin...

Characteristics

  1. Tentacles
    1. Median suckers of tentacular club greatly enlarged.**

  2. Funnel
    1. Funnel valve absent.
    2. Funnel organ: dorsal pad U-shaped with 3-7 papillae.

  3. Mantle
    1. Single tuberculate cartilagenous strip on mantle originates at each funnel-mantle fusion.*

  4. Fins
    1. Fins barely unite posterior to gladius (transversely elliptical in combined outline).

  5. Photophores
    1. Each eye with 5-21 oval photophores depending on species.
    2. Photophores on tips of arms III in mature or nearly mature females.
*Unique feature in family.
**Unique feature in family where suckers unmodified (not hooks or hook-like suckers)

Comments

This is the only genus in the subfamily Cranchiinae with paralarvae that have stalked eyes. Characteristics are from Voss (1980).

Comparison of species

 image info

Figure. Comparison of the structure of the mantle tubercular strips among five of the species. A - Leachia lemur, north Sargasso Sea, 42 mm mL. B - Leachia atlantica, subtropical North Atlantic, 54 mm ML. C - Leachia dislocata, off California, 34 mm ML. D - Leachia danae, eastern tropical Pacific, 53 mm ML. E - Leachia pacifica, off Hawaii, 41 mm ML. Drawings from Voss, et al. (1992, p. 191).

Life History

The paralarvae of the genus have a very distinctive appearance. A paralarva has a very long, slender brachial pillar and a pointed tip to the gladius. Paralarvae of Leachia were originally placed in the genus Pyrgopsis and are now often referred to as pyrgopsis paralarvae.

 image info

Figure. Dorsal and ventral views of paralarval L. pacifica, 7.9 mm ML, Hawaiian waters, original.

Distribution

Vertical distribution

Off Hawaii, L. pacifica has a peculiar vertical distribution pattern which may prove to be common within the genus. Small squid are found in near-surface waters. As sexual maturity approaches, the squid undergoes an abrupt ontogenetic descent. At depths greater than 1000 m males and females become mature. Large photophores develop on the tips of the third arms of females and these are, presumably, used to attract males at great depths where the risk of predation is low.

 image info

Figure. Vertical distribution chart of L. pacifica, 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 color - Night captures. Yellow color - Day captures. Chart modified from Young (1978).

References

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

Voss N. A., S. J. Stephen and Zh. Dong 1992. Family Cranchiidae Prosch, 1849. Smithson. Contr. Zool., 513: 187-210.

Young, R. E. 1978. Vertical distribution and photosensitive vesicles of pelagic cephalopods from Hawaiian waters. Fish. Bull. 76: 583-615.

Title Illustrations
Scientific Name Leachia dislocata
Location off California
Scientific Name Leachia dislocata
Reference from Young, R. E. 1972. The systematics and areal distribution of pelagic cephalopods from the seas off Southern California. Smithson. Contr. Zool. 97:1-159.
Size 110 mm ML
About This Page

Richard E. Young

Dept of Oceanography
University of Hawaii
Honolulu, Hawaii 96822
USA

Katharina M. Mangold (1922-2003)


Citing this page:

Young, Richard E. and Mangold (1922-2003), Katharina M. 1996. Leachia Lesueur, 1821. Version 01 January 1996 (under construction). http://tolweb.org/Leachia/19544/1996.01.01 in The Tree of Life Web Project, http://tolweb.org/

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