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The Conus Biodiversity Website

CATALOGUE OF RECENT AND FOSSIL CONUS

  Conus omaria Hwass in Bruguière, 1792.

Range: Indian Ocean except for Red Sea and India; Pacific Ocean except for French Polynesia and Hawaii.

Description: Medium-sized to large, moderately solid to solid. In Indian Ocean shells (Pl. 62, Figs. 22-25), last whorl narrowly conoid-cylindrical to conoid-cylindrical, also narrowly cylindrical to cylindrical or ventricosely conical in Pacific shells (Pl. 62, Figs. 14-21), conical in juvenile shells; outline straight and nearly parallel-sided to slightly convex or slightly concave centrally, variably convex above and slightly convex to straight below; left side sometimes concave above base. Aperture wider at base than near shoulder. Shoulder angulate to rounded. Spire usually low; outline concave to slightly convex in late whorls, domed to straight in early whorls. Larval shell multispiral, maximum diameter 0.7-0.8 mm. Teleoconch sutural ramps flat to slightly concave or slightly convex, with 2-4 fine spiral grooves in early whorls and numerous often very weak spiral striae in late whorls. Last whorl with fine spiral ribs or threads and a few narrow ribbons basally, obsolete toward shoulder.

Shell Morphometry
  L 45-86 mm
  RW 0.19-0.56 g/mm
     (L 45-77 mm)
  RD -
     (-Pacific shells 0.47 - 0.60; -Indian Ocean shells 0.45 - 0.56)
  PMD -
     (-Pacific shells 0.71 - 0.83; -Indian Ocean shells 0.75 - 0.83)
  RSH 0.06-0.13

Ground colour white, often suffused with pink to violet in Indian Ocean shells. Last whorl overlaid with yellowish or orangish brown to dark or reddish brown, leaving numerous very small to moderately large tentlike ground-colour markings. Tents edged with a darker brown line toward outer lip and usually concentrated in 3-4 axial bands as well as in 3 spiral bands, below shoulder, below centre and at base. Shells with 2 interrupted spiral bands of brown flecks and blotches intergrade with shells with a rather regular network of brown lines on entire last whorl; in some shells from Pacific localities (Philippines, Amami Is.), reticulated lines replaced by fine wavy axial lines (Pl. 62, Figs. 19, 20). Brown flecks and blotches with many very small, regularly arranged white spots, sparsely including larger solid zones, and interspersed with spiral rows of alternating darker brown and ground-colour dots. Larval whorls and first 2-4 postnuclear sutural ramps reddish violet. Following ramps matching last whorl in colour pattern. Aperture often yellow to pinkish orange, yellowish cream deep within.

Periostracum greyish to orangish yellow, thin, translucent, smooth.

Juvenile animal mottled white and pale red. Foot bright red at each end, both dorsally and ventrally; dorsum paler than sole. Tentacles largely white. Siphon red distally, with a black ring centrally. (Pearson, unpubl. observ.). In adults, dorsum of foot white, mottled with brown; lateral and posterior marginal zones with brown to black radial streaks and blotches as well as a black pre-marginal line ending in a lateral black blotch on anterior part; a median black blotch located at distal end of anterior part, sometimes fused with lateral blotches to a large trilobate black area. Anterior side of foot red-orange. Sole of foot white, mottled with brown. Rostrum white, with brown streaks and veins behind immaculate tip. Proboscis red, paler ventrally. Tentacles white, tipped with red or tan; base dorsally demarcated from the rostrum by a black blotch. Siphon white, edged with pale red, grading to dark coral red at tip, with sparse brown mottling distally and heavy mottling proximally; a broad black ring located 1/3 to 1/2 of the length from the tip (Chaberman, pers. comm., 1981; Pearson, unpubl. observ.) (Pl. 76, Fig 64; Pl. 84, Second row, Third row, left).

Radular teeth with 2 opposed barbs adapically; long serration of strong denticles ending in a cusp near base (Endean & Rudkin, 1965). Juvenile specimens (L about 1.4 mm) with radular teeth very similar to those of similarly sized C. magus (Nybakken, 1990).

Habitat and Habits: Shallow subtidal to about 50 m, as deep as 100 m in W. Thailand; on coral reefs and in reef lagoons, in sand and rubble. C. omaria feeds on gastropods including Cypraeidae, Olividae and Strombidae; venom does not affect mammals, fishes, and polychaetes (Pearson, unpubl. observ.; Endean & Rudkin, 1965). Ontogenetic change in radular tooth morphology suggests a shift in the diet from worms to molluscs (Nybakken, 1990). In Fiji, egg capsules of about 16 x 7 mm deposited in clusters; egg diameter of 336 µm and pelagic period of 12 days observed in Palau (Cernohorsky, 1964; Perron & Kohn, 1985).

Discussion: C. omaria is similar to C. magnificus, C. episcopatus, C. madagascariensis and C. pennaceus. C. magnificus has a higher spire (RSH 0.13-0.19), a white aperture, and largely solid rather than strongly interrupted brown flecks and blotches. Its early postnuclear whorls are consistently domed, and its ground colour is suffused with red, whereas sympatric C. omaria has a pure white ground colour. C. episcopatus is of larger mean size and has consistently domed early postnuclear whorls. It can be distinguished from C. omaria by its coarser pattern consisting of larger and more often axially elongate brown blotches, a much smaller portion of very small tents, and prominent axial bands of larger ground colour tents that are more often fused into axial white blotches. In addition, C. episcopatus lacks dark brown demarcation lines on the tents. For comparison with C. madagascariensis and C. pennaceus, see the Discussions of those species. Indian Ocean shells of C. omaria differ from Pacific shells in their often pale pink to violet ground colour, more frequently straight-sided apices and in their strictly conoid-cylindrical last whorls. These differences do not justify separation at the species level; as they are not constant between regions of the species range, neither do they suggest subspecies status. C. convolutus refers to Indian Ocean specimens with straight-sided apices; C. patonganus from W. Thailand includes specimens with domed as well as straight-sided early postnuclear whorls. C. magoides, described as "pink", may be based on a specimen from the Indian Ocean with a convex apex. C. viperinus is a yellowish to orangish brown form from Philippines with domed to sometimes straight- sided early postnuclear whorls. C. sindon has been considered to represent an individual variant of C. pennaceus with closely spaced axial lines (Walls, [1979]) or recognized as valid species separate from both C. omaria and C. pennaceus (da Motta, 1986, Richard, 1990). An axially lineate pattern occurs in various species (C. omaria; C. pennaceus; C. madagascariensis; C. textile; C. victoriae). In colour pattern, the holotype of C. sindon (Pl. 62, Fig. 21) is slightly closer to similar forms of C. omaria (Pl. 62, Fig. 19, 20) than to those of C. pennaceus (Pl. 64, Fig. 25; Lauer, 1990b, Fig. 96c); with respect to shell morphology, it cannot be unequivocally assigned to either of these species. We provisionally place C. sindon into the synonymy of C. omaria.

Range Map Image

C. omaria range map

This section contains verbatim reproductions of the accounts of 316 species of Conus from the Indo-Pacific region, from Manual of the Living Conidae, by Rckel, Korn and Kohn (1995). They are reproduced with the kind permission of the present publisher, Conchbooks.

All plates and figures referred to in the text are also in Rckel, Korn & Kohn, 1995. Manual of the Living Conidae Vol. 1: Indo-Pacific Region.

The range maps have been modified so that each species account has it own map, rather than one map that showed the ranges of several species in the original work. This was necessary because each species account is on a separate page on the website and not confined to the order of accounts in the book.

 

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