Asperoteuthis Nesis, 1980

Introduction

Little is known obout the biology of any species of Asperoteuthis. The most peculiar feature of this genus is the structure of the tentacular clubs. The distal half of the club has typical suckers and suggests that this part of the club functions in the usual capture of prey. The function of the bare proximal half of the club with its broad protective membranes is less clear but relates to another problem: How can the long and extremely slender tentacles, which in A. acanthoderma can be 7-12 times the mantle length (Tsuchiya and Okutani, 1993), be deployed? Perhaps the wide protective membranes of the proximal region of the club, which are composed virtually entirely of muscular trabeculae, function as muscular fins that swim the club into position.

Diagnosis

A chiroteuthid ...

• with suckers only on distal portion of tentacle-club.
• with atypical tragus and antitragus in funnel locking-apparatus which define a slender Y-shape or a slender curved groove.
• without photophores on arms IV.

Characteristics

1. Arms
   1. Long, subequal in length in large subadults.

2. Tentacles
   1. Club divided into two portions by symmetrical protective membranes.
   2. Suckers only on distal portion of club.
      image info

      Figure. Oral view of tentacular club of Asperoteuthis acanthoderma. Drawing by J. R. Schroeder.

3. Head
   1. Olfactory organ located well posterior to each eye.

4. Funnel
   1. Funnel valve present.
   2. Funnel-locking apparatus variable; with inverted Y-shaped groove that poorly defines a weak tragus and strong antitragus or a curved groove without an antitragus. image info

      Figure. Ventral view of the funnel locking-apparatus, A. acanthoderma. Drawing by J. R. Schroeder.

5. Photophores
   1. No photophores on viscera or arms IV.
   2. Large oval photophore patch on ventral surface of each eyeball.
   3. Luminescent pads on tentacles (also in Chiroteuthis).
   4. Aboral surface of club with large photophore on tip (see arrow) and two series of small photophores.
      
      
      image info image info image info

   Figures. Left - Ventral view of eye of Asperoteuthis acanthoderma from Tsuchiya and Okutani, 1993, showing photophore, with permission. Middle - Tentacle stalk photophores, same species. Drawing by J. R. Schroeder. Right - aboral view of club-tip photophore (arrow), Asperoteuthis sp. A. Drawing by A. D. Hart.

Comments

These squid generally lose the tentacles during capture and can easily be confused with Grimalditeuthis. However the lack of a fused funnel-mantle locking apparatus easily distinguishes them.

Nomenclature

Lu (1977) described Chiroteuthis acanthoderma. Nesis (1980) incorrectly synonymized this species with the incompletely described Chiroteuthis famelica Berry, 1909 (now = Mastigoteuthis famelica, see Young, 1991) and erected for it the new genus Asperoteuthis. The type species of the genus is C. acanthoderma Lu, 1977.

Discussion of Phylogenetic Relationships

Nothing is known of the phylogenetic relationships among the species.

Life History

Paralarvae are known for one species of Asperoteuthis (see Asperoteuthis sp. A).

References

Lu, C. C. 1977. A new species of squid Chiroteuthis acanthoderma, from the Southwest Pacific (Cephalopoda, Chiroteuthidae). Steenstrupia, 4: 179-188.

Nesis, K. N. 1980. Taxonomic position of Chiroteuthis famelica Berry. Bull. Moscow Obshch. Ispyt. Prirody, sect. Biology, 85: 59-66. [In Russian].

Tsuchiya, K. and T. Okutani. 1993. Rare and interesting squids in Japan -X. Recent occurences of big squids from Okinawa. Venus, 52: 299-311.

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

Young, R. E. 1991. Chiroteuthid and related paralarvae from Hawaiian waters. Bull. Mar. Sci., 49: 162-185.