IUCN threat status:

Least Concern (LC)

Comprehensive Description

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Description

Chiroteuthis veranyi (Ferussac, 1835)

 

 

Material: Two specimens. Specimen 1: 52°56.6'S, 36°11.1'W (c. 130 km north of South Georgia), 26 November 1981, RMT1 opened at 250 m, closed at 2000 m. Specimen 2 (Fig. 1): 53°22.0'S, 38°33.1'W (c. 65 km north of South Georgia), 30 January 1991, RLMT25 opened at 800 m, closed at 1000 m. Measure­ments and indices of the two specimens are given in Table I. All drawings were made from Specimen 1.

 

 

Description

 

Mantle (Figs 2, 3): Short, conical, with weak muscu­lature; terminates in a point posteriorly just beyond posterior end of fins; anterior mid-dorsal mantle margin a low point; ventral margin without protruberances.

 

 

Fins (Figs 2, 3): Almost circular with free anterior lobes; fins occupy half the mantle length.

 

 

Funnel (Fig. 4a): Moderate in size, free from head laterally; funnel valve small, well posterior to funnel opening. Dorsal funnel organ inverted v-shape with short, wide tapering limbs and a prominent central anterior papilla; ventral pads oval.

 

 

Funnel locking-cartilage (Fig. 4b): Oval with two !istinct knobs, a larger tragus and a smaller antitragus, 7rojecting towards centre of cavity.

 

 

Head (Figs 2, 3): Elongate, cylindrical, slightly swol­len in the region of the eyes. Two olfactory papillae, with stalks about 10 mm long with small terminal swellings, arise from ventro-lateral surface of head on each side of funnel opening. Eyes large, with a slight anterior and a small posterior sinus. Eyes of both specimens damaged. Buccal connectives attach to dorsal borders of Arms I and II, ventral borders of Arms III and IV.

 

 

Arms (Fig. 5): Formula IV>III>II>I in size and length. Arms I–III with thick, low keels, and with low protective membranes supported by trabeculae which are approximately equilateral triangle shape. Arm IV greatly enlarged, about twice mantle length, with a broad tentacular sheath running along its length. No protective membrane or trabeculae on Arm IV. Suckers on Arm IV widely separated in two alternating series, converged distally, giving the appearance of single row to arm tip. Largest suckers located basally on Arm IV, one-third arm length from arm base on Arms I–III. Suckers on all arms reduced in size distally towards arm tip, becoming crowded at distal end. Distal two-thirds of largest sucker rings (Fig. 6) with 12-16 distinct triangular teeth, proximal one-third of sucker rings scalloped.

 

 

Tentacles (Figs 2, 3): Long, slender, about 6-7 times mantle length, white with purplish specks over sur­face. Numerous loosely adhered "knobs" of unknown function, but thought to be photophores, on aboral sur­face of tentacular stalk. "Knobs" oval with flattened surface and with purplish pigmentation. An estimate of the number of "knobs" present was impossible because so many had been lost during capture and preservation. "Knobs" decreased in diameter distally towards the club, appeared as dark spots at regular intervals on aboral surface of club.

 

 

Club (Fig. 7): Flattened, widest at proximal portion, each side bordered by well developed protective membrane supported by a series of transverse, thick muscular trabeculae. Ends of trabeculae project at edge of membrane. Trabeculae fused with tentacle on oral side. Trabeculae on distal half of club separated by spaces similar in width to their breadth. Trabeculae on proximal half of club forked, crowded with narrow spaces in between, those on proximal one-third fused. A thick, ovate dark purple indented photophore about 2.5 mm long, at tip of club. The spoon-like indentation visible from the aboral side of club

 

 

Club suckers (Fig. 8): A total of 133-136 suckers in about 35 tetraserial rows. Suckers set on long and short medial stalks. Stalks composed of basal part and shorter (about half length of basal part) distal sucker-bearing part, separated by a short purple pleated "skirt". A transparent keel, running along length of each stalk, fuses with protective membrane between trabeculae. Lateral suckers slightly wider than medial suckers. Distal half of sucker ring (Fig. 9) with a prominent central recurved median tooth flanked by two triangular teeth on each side, proximal half of sucker ring smooth. Rings on medial suckers about two-thirds the diameter of those on lateral suckers.

 

 

Radula (Fig. 10): Seven transverse rows of teeth. Rachidian with a long central tooth flanked short, blunt lateral cusps. First lateral tooth bicusped with a long, pointed median cusp and a small blunt lateral cusp. Second lateral tooth pointed, with a broad base and a subtle medial blunt shoulder. Third lateral, tooth long, slightly curved, pointed. Marginal plates absent.

 

 

Chromatophores (Fig. 1): Numerous pink-purple, chromatophores cover body, fewer on tentacles, absent on club keels.

 

 

Photophores: Two large, round prominent photophores lie one on each side of the ink sac. Large regular-spaced photophores lie along oral sides of Arms IV at base of tentacular sheath. Single photophore at tip of each tentacular club and presumed photophores on the tentacular stalks. Eye photophores - strips of golden brown luminous tissue around the eye.

 

 

Beak (Fig. 11): Upper mandible with long curved rostrum. Lower mandible with obtuse jaw angle, high wingfold thickened to form a ridge, long wing, short crest; hood long relative to crest and broadly notched in the midline; thickened fold running to lower part of posterior edge of lateral wall.”

 

 

                                                                                            
 

Parameter

 
 

Specimen 1

 
 

Specimen 2

 
 

 
 

Measurement (mm)

 
 

Index (%)

 
 

Measurement (mm)

 
 

Index (%)

 
 

Mantle length

 
 

107

 
 

-

 
 

96

 
 

-

 
 

Mantle width

 
 

34

 
 

32

 
 

33

 
 

34

 
 

Fin length

 
 

56

 
 

52

 
 

47

 
 

49

 
 

Fin width

 
 

54

 
 

50

 
 

50

 
 

52

 
 

Arm length I

 
 

82

 
 

77

 
 

114

 
 

119

 
 

Arm length II

 
 

124

 
 

116

 
 

125

 
 

130

 
 

Arm length III

 
 

146

 
 

136

 
 

135

 
 

141

 
 

Arm length IV

 
 

201

 
 

188

 
 

245

 
 

255

 
 

Club length

 
 

50

 
 

48

 
 

52

 
 

54

 
 

Tentacle length

 
 

700

 
 

654

 
 

670

 
 

698

 
 

Eye diameter

 
 

13

 
 

12

 
 

14

 
 

15

 
 

 

Rodhouse & Lu, 1998: 311-316

Trusted

Creative Commons Attribution Non Commercial 3.0 (CC BY-NC 3.0)

© National Museum of Natural History, Smithsonian Institution

Source: Antarctic Invertebrates Website (NMNH)

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