Planctoteuthis exopthalmica (Chun 1910)

Introduction

P. exopthalmica is poorly known as the original description was based on a 25 mm and a 9.5 mm ML paralarva. The 9.5 mm ML specimen, taken from the Indian Ocean, was designated as the lectotype (i.e., a "holotype" designated from the original type series) by Glaubrecht and Salcedo-Vargas (2000:274). The 25 mm ML specimen, taken in the North Atlantic, has been placed in the synonomy of P. levimana by Young et al. (2006). The most distinguishing feature of the small lectotype is a slender, unexpanded club, a feature shared with P. levimana. P. exopthalmica may eventually prove to be a junior synonym of P. levimana.

Characteristics

1. Arms
   1. Arms IV bear uniserial suckers.
   2. Arms IV 7 mm long.
   

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   Figure. Oral view of a portion of arm IV of P. exopththalmica, 9.5 mm ML. Drawing from Chun (1910).

2. Tentacular clubs
   1. Club not expanded
   2. Low, thick protective membranes along dorsal and ventral borders.
   

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   Figure. Oral view of the tentacular club of P. exopththalmica, 9.5 mm ML. Drawing from Chun (1910).

3. Head
   1. Head and neck 8 mm to base of arms.
   2. Oblong cone laterally carries strongly protruding eyes.
   3. Eyes with very long ventral process.
   

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   Figure. Side view of the head and eye of P. exopthalmica, 9.5 mm ML. Drawing from Chun (1910)

4. Fins
   1. Dorsal base of fins short (1.5 mm).
   2. Combined width of fins 3.8 mm.

Comments

Most of Chun's description was based on the larger specimen which no longer is placed in this species. Chun states, "The smaller specimen from the Indian Ocean closely resembles the [larger] specimen in all important characters." However, we reproduce here only information specifically based on the small lectotype.

Nomenclature

This species was originally described by by Chun (1908) as Doratopsis exopthalmica and was placed in Planktoteuthis by Young (1991) due to the characteristic ventrally protruding eyes and shape of the fins.

Life history

Distribution

Geographical distribution

The lectotype is from the temperate South Indian Ocean at 43° 13'S, 80° 30'E.

References

Chun, C. 1908. Ueber Cephalopoden der Deutschen Tiefsee-Expedition, Zoologischer Anzeiger, 33: 86-89.

Chun, C. 1910. Die Cephalopoden. Oegopsida. Wissenschaftliche Ergebnisse der Deutschen Tiefsee-Expedition, "Valdivia" 1898-1899, 18: 1-522 , Atlas.

Glaubrecht, M. and M.A. Salcedo-Vargas. 2000. Annotated type catalogue of the Cephalopoda (Mollusca) in the Museum fur Naturkunde, Humboldt University of Berlin. Mitteilungen aus dem Museum fur Naturkunde Berlin, Zoologischen, 76(2):269-282.

Pfeffer, G. 1912. Die Cephalopoden der Plankton-Expedition. Ergebniss der Plankton-Expedition der Humboldt-Stiftung. 2: 1-815.

Young, R. E., M. Vecchione, U. Piatkowski and C. F. E. Roper. In press. A redescription of Planctoteuthis levimana (Lonnberg, 1896) (Mollusca; Cephalopoda), with a brief review of the genus. 2006. Proc. Biol. Soc. Washington, 119 (4): 586-591.