Range: Indian Ocean: Réunion, Seychelles, Madagascar, N. W. Australia, Maldives, and W. Thailand; Pacific: Okinawa, Guam, Philippines, and Marshall Is.

Description: Small and light. Last whorl ventricosely conical to ovate, sometimes conical in small specimens; outline slightly convex, straighter toward base. Shoulder rounded to indistinct. Spire of moderate height to high, outline convex to domed. Larval shell of about 4 whorls, maximum diameter about 0.9 mm. First 1-3 postnuclear whorls weakly tuberculate. Teleoconch sutural ramps almost flat, with l increasing to 2-3 spiral grooves, very weak in latest whorls. Last whorl with weak spiral ribs at base.

Colour orange to olive-brown, often tinged with violet; violet colouration may be restricted to base and columella. Last whorl with a lighter central band variably flecked with white and occasionally adapically bordered with brown dots. Larval whorls and early postnuclear sutural ramps yellow. Following sutural ramps also immaculate or with brown blotches. Aperture light violet behind a marginal ground-colour zone.

Periostracum light brown and translucent.

Habitat and Habits: In 10-30 m.

Discussion: C. nucleus is similar to C. luteus, C. granum, C. corallinus, and C. viola. C. luteus attains larger size (to 54 mm), has a narrower and rather cylindrical last whorl (RD 0.42-0.53), and its last whorl pattern is stronger including dotted to dashed spiral lines. C. corallinus differs in its more distinct shoulder, more conical shape of last whorl, rather clouded last whorl pattern including dotted or dashed spiral lines, its red rather than yellow larval shell, and its more prominent spiral sculpture on the early teleoconch sutural ramps; its base and columella are not tinged with violet. C. viola is also larger (to 48 mm), has a narrower (RD 0.43-0.51) and rather cylindrical last whorl, subangulate shoulder, stepped late postnuclear whorls, and a strong colour pattern on the last whorl. For comparison with C. granum, see the Discussion of that species.

C. nucleus 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 Röckel, 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 Röckel, 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.