Range: Indonesia to Philippines and Melanesia; additional localities in literature probably refer to C. achatinus.

Description: Medium-sized to moderately large, moderately solid. Last whorl ventricosely conical, outline variably convex. Aperture wider at base than near shoulder. Shoulder angulate, occasionally subangulate. Spire of low to moderate height, outline straight to slightly concave. Larval shell of 2.5-3 whorls. About first 4-5 postnuclear whorls weakly tuberculate. Teleoconch sutural ramps flat to faintly concave, with 1-2 increasing to 4-6 spiral grooves; spiral sculpture weak on latest ramps. Last whorl with rather widely set, sometimes granulose spiral ribs on basal fourth or third.

Ground colour white, heavily suffused with various shades of blue-grey or beige. Last whorl with a nebulous pattern of greenish grey to blackish brown axial flames, clouds and flecks often coalescing into a coarse irregular meshwork. On either side of centre, axial markings denser and emphasized by an underlying greenish beige to tan spiral band; a paler spiral band often below shoulder. Spiral rows of brown dots and dashes, with or without intermittent white dashes, cover entire last whorl or are restricted to the basal area. Larval whorls brown. Teleoconch sutural ramps heavily maculated with dark brown radial markings, sometimes with regularly spaced dots at both margins of the ramp. Aperture bluish white.

Habitat and Habits: Shallow subtidal; in sand, muddy sand and mud. Reported to live in mixed colonies with C. achatinus in E. New Britain (Richards, 1989).

Discussion: C. monachus is often confused with C. achatinus. C. monachus appears rather uniformly greenish blue, while C. achatinus is more variable in colour and pattern; the latter species has more pronounced dotted spiral lines on its last whorl, more tuberculate postnuclear whorls, a lighter-coloured larval shell, and more prominent spiral sculpture on both last whorl and sutural ramps. Where both species occur together, they apparently do not intergrade, supporting separation at the species level. For comparison with C. striolatus see DISCUSSION of that species. C. contusus (Pl. 15, Fig. 13) is probably a colour variant ofC. monachus with a solid beige shell with sparse faint spiral lines, but this has not been conclusively determined.

C. monachus 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.