Conus (Puncticulus) arenatus  Hwass in Bruguière, 1792

Common Name

"Sand Dusted Cone"

Status

Regarded as a valid species.

Type Locality

"Philippines"

Distribution

E. Africa to Marshall Is. and Tuamotu Archipelago

Maximum Reported Size

83.8 mm

Description

Medium-sized to large, moderately solid to moderately heavy; maximum size smaller in eastern populations. Last whorl usually ventricosely conical in eastern populations, conical to sometimes broadly conical in the W. Indian Ocean; outline convex, sometimes straight centrally. Siphonal fasciole distinct, occasionally separated from basal zone by an incision. Shoulder subangulate to rounded, weakly to strongly tuberculate. Spire of low to moderate height, outline straight to moderately convex. Postnuclear spire whorls tuberculate. Teleoconch sutural ramps concave, with 1 increasing to 4-6 spiral grooves. Last whorl with weak spiral ribs at base; in subadults and small adults, ribs may be granulose and extend to shoulder.

Ground colour white. Last whorl with spiral rows of brown or black dots, clustered in 2-3 interrupted spiral bands or in axial zigzag flames; dotted areas often with underlying grey shadows, most conspicuous within spiral bands. Opaque white dashes often irregularly alternating with dark dots. Larval whorls white. Teleoconch sutural ramps variably maculated with axial clusters of brown and black dots. Aperture white, brown or pinkish orange deeper within.

Periostracum thin, velvety smooth and either translucent olive or reddish brown and opaque; large and some subadult shells usually with a thicker, opaque operculum.

Dorsum of foot cream, mottled with yellowish brown, with a dark brown to black central spot at anterior end occasionally followed by a few grey to black dots; sometimes a dotted black pre- marginal line on posterior part. Anterior edge of foot may be orangish brown. Sole of foot white to brown, sometimes darker anteriorly, mottled with tan and sometimes longitudinally streaked with brown; mottling often more pronounced laterally. Rostrum yellow. Tentacles white to pale yellow. Siphon white or pinkish white, tip orange or mottled with red; central part with a single black dorsal blotch or a narrow black to grey ring; proximal part often mottled with tan (Pl.74, Fig. 23) (Chaberman, pers. comm., 1981; Kohn, unpubl. observ.; Pearson, unpubl. observ.).

Radular teeth with an adapical barb opposite a large second barb; serration ends in a cusp; base with spur (Peile, 1939).

Shell Morphometry

L 35-67 mm
(eastern populations; 35-90 mm W. Indian Ocean populations)
RW 0.20-1.10 g/mm
RD 0.60-0.72
PMD 0.75-0.85
(eastern populations; 0.84 - 0.89 W. Indian Ocean populations)
RSH 0.08-0.19

Habitat & Habits

Intertidal to about 30 m, living almost exclusively in sand. Mainly on wide stretches of sand on intertidal to shallow-subtidal reef flats; occasionally also in rubble mixed with sand, in mud among mangroves or on heterogeneous reef substrate (Kohn, 1961a/1968; Kohn & Nybakken, 1975; Reichelt & Kohn, 1985; Cernohorsky, 1964/1978; Sharabati, 1984). C. arenatus feeds on polychaetes of the families Capitellidae, Maldanidae, Nereidae and Eunicidae. Melo amphora Lightfoot is known to prey on C. arenatus (Kohn, 1968; Kohn & Nybakken, 1975; Reichelt & Kohn, 1985; Loch, pers. comm., 1987).

Discussion

C. arenatus resembles C. pulicarius in shell characters and often also in body colouration; for comparison, see the Discussion of the latter species. Coomans et al. (1979, 1981, 1982) recognize 3 geographical subspecies: C. arenatus (Indonesia and Pacific); ssp. aequipunctatus (Pl. 11, Fig. 3) (Red Sea; Gulf of Aden) and ssp. bizona (Pl. 11, Fig. 2) (Kenya to Thailand). However, the pattern differences between the two western subspecies are not constant. Although ssp. bizona was described as having two bands and ssp. aequipunctatus as having three, the third band is incomplete or lacking in some specimens from the Red Sea and Gulf of Aden, and it is present in some specimens from Sri Lanka. As noted above, W. Indian Ocean shells differ in size and shape from those farther east. In f. mesikatharos the central part of the last whorl is unspotted, form granulosa bears granules on the entire last whorl, and form undata shows dots arranged in flame-like axial clusters.

Related Taxon

References

Geographic Distribution


Image courtesy of A.J. Kohn