Leptoconus petasus (Ludbrook, 1978)

 

 

 

Shell large, obconic, with a gradate sharply-pointed concavely-elevated spire, flattening on the periphery, of varying height from one-fifth to one-third height of shell; protoconch small of 2 high smooth whorls, adult whorls 10, each almost completely embracing the previous whorl, shoulder angulate, sutural ramp flat to concave, surface smooth but for concave axial growth striae above the shoulder reflecting the sinus in the outer lip and about 12 weak lirae on the base of the last whorl; last whorl large, narrow and straight in profile in young shells but becoming broader and convex in profile in older specimens. Aperture fairly narrow, oblique, outer lip parallel to the columella, margin convex below and sinuate above the shoulder, columella gently convex, with a strong tooth-like callus anteriorly bordering the siphonal canal. Two specimens show a colour pattern of spiral rows of fine dots on the last whorl (1).

 

Dimensions:                      height       height of spire       diameter

WAM         69.523      109                   21                    57

69.385       64                   10                    41

69.525       50                   16                    21

70.38         66                   12                    33

 

Remarks: This species is very close to C. (L.) monile Hwass in Bruguière (1792). The lack of spiral sculpture on the spire whorls which have only axial growth striae reflecting the apertural sinus is the same in both species. The spire tends to be larger in C. (L.) petasus. The colour pattern of C. (L.) monile (“necklace”) is that of a number of spiral rows of dots like a series of necklaces of different-sized beads whereas in C. (L.) petasus it may be likened to bands of fine seed-pearl necklaces. In this the pattern is more like that of C. (L.) nielsenae Marsh as figured by Wilson & Gillett (1971, pl. 101, fig. 5). The strong tooth-like callus at the base of the columella is not present in C. (L.) monile. The specific name is given because of the faint resemblance of the spire to a conical sun-hat. Paratype WAM 69.525 is an immature shell with an unusually high gradate spire; the anterior tooth-like callus is well developed.

 

Distribution: Roe Calcarenite; Early Pleistocene.

 

 

 

 

Conus petasus(1)

Plate 21 – figg. 1-5

 

1, 2. WAM 69.523, holotype.

3. WAM 69.525, paratype.

4. WAM 69.385, paratype. ( ? )

5. WAM 70.38, paratype.

 

 

 

 

 

 

Conus petasus(1)

WAM 69.523, holotype

Plate 21 – figg. 1-2

mm. 109 x 57

 

Conus petasus(1)

WAM 70.38, paratype

Plate 21 – fig. 5

mm. 66 x 33

 

Conus petasus(1)

WAM 69.385, paratype

Plate 21 – fig. 4

mm. 64 x 41

 

Conus petasus(1)

WAM 69.525, paratype

Plate 21 – fig. 3

mm. 50 x 21

 

 

 

 

 

 

 



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