Abraliopsis lineata (Goodrich 1896)

Introduction

A. lineata is a relatively small-sized species, which attains 30 mm DML. It is widely distributed in the Indo-West Pacific.

Brief diagnosis:

An Abraliopsis (Micrabralia) ...

• without keels and carpal flaps on tentacular clubs.
• with largest club hook of ventral series <1.5 X height of dorsal counterpart. 
• with enlarged ventral trabeculae bearing tubercules on arms I of males.
• with bases of arms II swollen in males.
  

Characteristics

1. Tentacle clubs
   1. Two rows of subequal-sized hooks on manus (ventral hooks < 1.5 x dorsal hooks).
   2. Carpal flap and aboral keel absent.
      

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      Figure. Oral view of the tentacle club of A. lineata, Arabian Sea. Drawing from Tsuchiya et al. (1991).
      

2. Arms
   1. Arms IV are moderate in length; ALI IV = 50-65.
   2. Arms I-III with 14 - 18 (females) or 19-25 9 (males) hooks, and with distal suckers.
   3. Female with 10-12 hooks on arm IV.
      
   4. Males with well developed, spatulated trabeculae in protective membranes and numerous minute tubercles on oral surfaces on arms I.
   5. Males with swollen arms II, about twice thickness of other arms, and with some tubercules on ventral membrane.
   

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   Figure. Oral views of arms of A. lineata, Arabian Sea. Left - 23 mm ML, female. Middle, right - 23 mm ML, both arms from same male. Drawings from Tsuchiya, et al. (1991).
   

3. Hectocotylus and male sexual dimorphism
   1. Hectocotylus with two subequal-sized offset flaps ventrally; one subequal flap dorsally.
   2. Modified portion without armature.
   

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   Figure. Hectocotylus (right arm IV) of A. lineata, 27 mm ML, Arabian Sea. Top - Oral view. Bottom - Dorsal view. Drawings from Tsuchiya, et al. (1991).
   

4. Integumental Photophores
   1. Ventral mantle with six narrow longitudinal stripes of large integumental organs and scattered small organs between stripes; a distinct, narrow, mid-ventral photophore-less strip present.
   2. Ventral head with three rows of narrow, longitudinal stripes and some scattered organs in between.
   3. Stripes of organs along ventral side of arm III and dorsal side of arm IV are interrupted.
   

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   Figure. Ventrolateral view of the head photophors of A. lineata, 23 mm ML, female, Arabian Sea. Drawing modified from Tsuchiya, et al. (1991).
   

Comments.

See Abraliopsis (Micrabralia) page for comparisons among all species of the subgenus. 

Distribution

Vertical Distribution

A. lineata was found during the day at depths as shallow as 100m above an oxygen-poor layer in Arabian Sea (Tsuchiya et al., 1991).

Geographical Distribution

Type locality - Andaman Sea and off Ganjam coast (Indian Ocean).

This species is distributed in widely in the tropical Indo-West Pacific from the Mascarenes (Chun, 1910; Nesis, 1982/87, eastward to Ryukyu Island, Japan, Indonesia and Polynesia (Nesis, 1982/87; Tsuchiya, pers.obs.). In the southwestern Pacific, it reaches farther to the south than 15° S.

References

Chun, C. 1910. Die Cephalopoden. Oegopsida. Wissenschaftliche Ergebnisse der Deutschen Tiefsee Expedition auf dem Dampfer "Valdivia" 1898-1899, 18(1):1-401.

Nesis, K. N. 1982/87. Abridged key to the cephalopod mollusks of the world's ocean. 385+ii pp. Light and Food Industry Publishing House, Moscow. (In Russian.). Translated into English by B. S. Levitov, ed. by L. A. Burgess (1987), Cephalopods of the world. T. F. H. Publications, Neptune City, NJ, 351pp.

Tsuchiya, K., Piatkowski, U., and Okutani, T. 1991. Distribution and re-description of Abraliopsis lineata Goodrich, 1896 (Cephalopoda: Enoloteuthidae) from the Arabian Sea. J. nat. Hist., 25:1121-1133.