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Common Name

"Sharp Angled Cone"

Status

Regarded as a valid species.

Type Locality

"Mers des Grandes Indes"

Distribution

Indo-Pacific

Maximum Reported Size

35 mm

Description

Small to medium-sized, light to moderately solid. Last whorl conical to broadly conical or slightly pyriform; outline nearly straight to slightly sigmoid. Shoulder angulate to carinate, smooth to tuberculate, with a deep exhalent notch. Spire usually high, outline variably concave. Larval shell of 3.5-4 whorls, maximum diameter of 0.8-0.9 mm. First 8-10 postnuclear whorls tuberculate, following whorls undulate to smooth. Teleoconch sutural ramps flat to slightly concave, with 0 increasing to 3-6 spiral grooves crossed by arcuate radial threads. Last whorl with strong spiral ribbons or ribs, separated by narrow to occasionally broad spiral grooves with strong axial threads.

Ground colour white. Last whorl variably patterned with light to dark brown: Largely brown except for small scattered ground-colour blotches at shoulder and centre, or white flecked with brown, or white spirally spotted with brown, or all white. Larval whorls white. Spire variably streaked with brown. Aperture white.

Periostracum brown, thin, translucent, smooth.

Dorsum of foot white to pale yellow, with adotted brown wing-shaped pattern on anterior part continuing as a dotted brown pre-marginal line posteriorly; anterior edge with a black spot on each side of a triangular brown central fleck. Sole of foot white. Tentacles white, suffused with tan and tipped with black. Siphon white, suffused with beige to light brown dorsally; tip immaculate (Red Sea: Fainzilber et al., 1992; Papua New Guinea: Chaberman, pers. comm., 1981). Sole of foot buff anteriorly and light brown posteriorly. Rostrum buff. Siphon buff at tip, darker tan proximally (Hawaii: Kohn & Weaver, 1962) (Pl. 76, Fig. 61).

Shell Morphometry

L	22-38 mm
RW	0.04-0.13 g/mm
RD	0.65-0.75
PMD	0.80-0.93
RSH	0.23-0.37

Habitat & Habits

Usually in 3-100 m, adults sometimes in 0.5-5 m, juveniles sometimes as deep as 180 m. On coral or shell sand often mixed with coral rubble, on muddy sand and on fine shell rubble with seaweed (Fainzilber, 1985; Fainzilber & Mienis, 1986; Fainzilber et al., 1992; Grosch, pers. comm., 1989; Tirard, pers. comm., 1989).

Discussion

C. acutangulus resembles C. milesi, C. praecellens, C. tuberculosus, and C. helgae. C. milesi is smaller (to 27 mm) and has a narrower last whorl (RD 0.49-0.59) and a paucispiral larval shell (1.75-2 whorls). C. praecellens is larger (to 63 mm) and differs in the absence of tubercles on its late postnuclear whorls, the greater number of spiral grooves on its late sutural ramps, and in the lower number of whorls of its larval shell (about 2.5 whorls). For comparison with C. tuberculosus and C. helgae, see the Discussions of those species. C. turriculatus (Pl. 54, Fig. 22) and C. gemmulatus refer to white shells of C. acutangulus.

Related Taxon

f. turriculatus

References

• Lamarck, J. B. P., 1810. Sur la determination des especes. Annales du Muséum d'Histoire Naturelle (Paris), 15: 1 -442.
• Röckel, Korn & Kohn, 1995. Manual of the Living Conidae Vol. 1: Indo-Pacific Region.