Asperoteuthis Nesis, 1980

Introduction

Little is known about the biology of any species of Asperoteuthis. The most peculiar feature of this genus is the structure of the tentacular clubs. The distal part of the club has typical suckers and suggests that this part of the club functions in the usual capture of prey. The proximal part of the club lacks suckers and has broader protective membranes whose trabeculae are mostly fused. The function of the latter 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, generally subequal in length in large subadults with arms IV slightly longer.
      
      
2. Tentacles
   1. Club divided into two portions by symmetrical protective membranes.
   2. Suckers only on distal portion of club.
      

      Click on an image to view larger version & data in a new window

      

      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 component of the funnel-mantle locking-apparatus variable; with inverted Y-shaped groove that poorly defines an elongate tragus and slender antitragus (A. acanthoderma) or a slender antitragus and a strong antitragus (A. lui) or a curved groove without an antitragus (A. mangoldi).
      
      

      Click on an image to view larger version & data in a new window

      
      

      Figure. Ventral view of the funnel locking-apparatus. Left - A. acanthoderma. Drawing by J. R. Schroeder. Middle - A. lui. Drawing from Braid (2016). Right - A. mangoldae. Drawing from Young, et al. (2007).
      

5. Integument
   1. Skin covered with small tubercules in A. acanthoderma and A. lui but without tubercules in A. mangoldae.
      
      

      Click on an image to view larger version & data in a new window

      
      

      Figure. Integument of A. acanthoderma, mature female, showing tubercules. Photographs by Chuck Stevenson.

6. Tail
   1. Tail with “secondary fin” retained in adults.
      
      
7. Photophores
   1. Photophores absent from viscera and arms IV.
   2. Large photophore patch on ventral surface of each eyeball.
   3. Luminescent pads on tentacle stalks (also in Chiroteuthis).
   4. Aboral surface of club with large, distal photophore (see arrows - terminal position in A. acanthoderma and A. mangoldi, not considering the long, terminal papilla in the latter, well sub-terminal position in A. lui) and a lateral series of small photophores on each side of the aboral club in A. acanthoderma and A. mangoldi (not shown on drawing of latter) and these plus an additional series of midline photophores in A. lui.
      

      Click on an image to view larger version & data in a new window

      
      

      Figures. Left - Ventral view of eye of Asperoteuthis acanthoderma. Drawing from Tsuchiya and Okutani, 1993, showing photophore, with permission. Middle - Tentacle stalk photophores, same species. Drawing by J. R. Schroeder. Right - aboral views of tentacle club showing photophores. Large distal photophore indicated by arrows. Drawing of A. lui from Braid (2016). Drawing of A. acanthoderma from Lu (1977). Drawing of A. mangoldae from (Young et al., 2007).
      

Comments

These squid generally lose the tentacles during capture and can easily be confused with Grimalditeuthis (especially A. mangoldae which is of the same size and muscular consistency). However the lack of a fused funnel-mantle locking apparatus easily distinguishes them.

Comparison of major differences between species:

Other characters also separate some or all of the species (e.g., shape of the ocular pphotophore, fin, secondary fin, club and mantle, presence of a long terminal-club papilla).

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 mangoldae).

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.

Young, R. E., M. Vecchione and C. F. E. Roper. 2007. A new genus and three new species of decapodiform cephalopods (Mollusca: Cephalopoda). Rev. Fish. Biol. Fisheries, 17: 353-365.