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Classification


Geographic Distribution

Antarctic Convergence illustration Antarctic convergence

Bathymetric Specimen Dispersal

32 individual specimens found for Cilunculus acanthus.

Cilunculus acanthus Fry & Hedgpeth  Species

Synonymy

Original Description
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Original Description
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Cilunculus acanthus n. sp. (Fig. 207-209)

MATERIAL EXAMINED: --

Eltanin Sta. 268, 10 males, 6 females, 1 juv.

Holotype, 1 ovigerous male, U.S.N.M. No. 112003; allotype, female U.S.N.M. No. 113004; Paratype male B.M. (N.H.) Regn. No. 1966.3.11.4; female paratype, B.M. (N.H.) Regn. No. 1966 3.11.5

DESCRIPTION: -- Based on 16 adults and 1 juvenile.

PALP: Palp 9-segmented, terminal segments with a dense armature of long spines ventrally.

PROBOSCIS: Proboscis shape B:1, not much longer than wide, mouth large, triangular.

TRUNK: Trunk rather stout but graceful; lateral processes widely separated and diverging so that their ends describe an ellipse; trunk somites articulated, raised posteriorly in ring-like expansions. Each trunk somite except the last has a tall pointed median dorsal tubercle on the posterior swelling, that of the cephalic somite being the lowest; ocular tubercles two or three times taller than the trunk tubercles, slender and pointed; eyes indistinct, near the tubercle apex; abdomen about three-quarters the trunk length, swelling to its largest diameter near the tip; a very long, erect, slender spine at the median dorsal distal margin of each lateral process, lateral and dorsal spines at the middle of the abdomen.

CHELICERAE: Chelicerae 3-segmented, long spines at the end of the 2nd segment; chelae subchelate, small.

OVIGER: Oviger of male large, stout, 10-segmented, 7th segment with recurved spines, terminal segment with two heavy denticulate spines with four large denticulation on each side; single large denticulate spines on segments 8 and 9, and probably also on segment 7.

LEGS: Female slightly slenderer in general aspect, with slightly swollen femur, without the conspicuous cement gland tube; somewhat less spinose than male. Very long, straight spine at end of femur in both sexes, this is often broken off. Many, slender, curved spines on coxae and long segments of legs. These spines are several times as long as the diameter of the leg segments; long straight cement gland tubercle just beyond the middle of the femur in the male. The cement gland lies just beneath the dorsal part of the broad base of the tubercle; propodus without basal spine or heel; terminal claw about half as long as propodus; accessory claws absent.

Dimensions

Holotype

Allotype

Male

Female

Trunk length

3.5 mm

3.75 mm

Proboscis length

1.8

2.0

Proboscis width (max)

1.5

1.5

Abdomen length

2.8

3.0

Cephalic somite length

1.5

1.25

2nd lateral process width

3.3

3.3

Third leg:

Coxa 1

0.8

0.8

Coxa 2

1.2

1.0

Coxa 3

0.8

0.8

Femur

2.5

2.4

Tibia 1

3.2

3.2

Tibia 2

2.9

3.0

Tarsus

0.1

0.1

Propodus

0.9

1.0

Main claw

0.6

0.6

Total leg length

13.0

12.9

DISTRIBUTION: -- The type locality is 64°1.2’S, 07°44’7” to 64°07’S, 67°44’W, depth approximately 2,700 m.

DISCUSSION: -- This species differs from others of its genus in lacking accessory claws. As Hedgpeth (1949) has suggested, the presence or absence of auxiliary claws is probably not a good generic character in the Ammotheidae (cf. Austroraptus). Cilunculus acanthus appears to be closest to C. hirsutus Clark, from New South Wales, but is distinct in the structure of the male oviger, size and position of the large femoral cement gland tube, and shape and size of the proboscis, which is shorter and more globose than in hirsutus. C. acanthus also has fewer denticulations on the ovigeral spines. The chela lacks the peg-like dactyl described for C. hirsutus; in C. acanthus it is a blunt lobe.” (Fry & Hedgpeth 1969, p. 126)

Geographic Distribution

The type locality is 64°1.2’S, 07°44’7” to 64°07’S, 67°44’W, depth approximately 2,700 m.

Remarks

****IN DISTRIBUTION – should type locality 07°44’7” be 67°44’7”? *****

Specimens

Type Status Catalog No. Date Collected Location Coordinates Depth (m) Vessel
Holotype 113003 8/20/1962 Antarctic Ocean 62.08° S, 67.74° W 2763 – 2818 Eltanin R/V
Paratype 152764 8/20/1962 Antarctic Ocean 62.08° S, 67.74° W 2763 – 2818 Eltanin R/V
Allotype 113004 8/20/1962 Antarctic Ocean 62.08° S, 67.74° W 2763 – 2818 Eltanin R/V
  181069 3/27/1971 South Atlantic Ocean 36.09° S, 52.3° W 2440 – 2480 Atlantis II R/V
  1122795 12/4/1962 Scotia Sea 55° S, 58.9° W 2452 Eltanin R/V
  1122807 12/21/1971 Antarctic Ocean 62.29° S, 58.58° W 55 – 78 Hero R/V
  1122808 3/9/1973 Antarctic Ocean 64.87° S, 63.54° W 96 – 133 Hero R/V

View additional taxa  View all species collected at same locations as Cilunculus acanthus