Medium-sized to moderately large, moderately solid to solid. Last whorl slightly ventricosely conical to conoid-cylindrical, outline convex; left side concave abapically. Shoulder angulate, strongly tuberculate. Spire of low to moderate height, outline straight to slightly concave. Postnuclear spire whorls tuberculate. Teleoconch sutural ramps concave in late whorls, with 2-3 distinct to obsolete spiral grooves. Last whorl with weak spiral ribs on basal fourth; ribs often granulose and extending up to shoulder (form deburghiae).
Ground colour white. Last whorl with 2 broad blackish brown spiral bands, above and below centre. White zones with dark brown reticulate lines. Teleoconch sutural ramps with irregularly spaced brown reticulate lines. Aperture white.

C. nocturnus is most similar to C. bandanus. We accept the conclusion of Coomans et al. (1985b) that it is a distinct species. C. bandanus attains larger maximum size (to 150 mm) and has a more conical last whorl with straighter outline. The banding pattern of C. nocturnus is most similar to C. bandanus form equestris from the Moluccas, which is also similar in size. However, the latter differs in shape as mentioned above, has a more pronounced tent-marked pattern, and has a lower spire (RSH 0.07-0.10). C. nocturnus has recently been found living together with C. bandanus and C. marmoreus in Seram, Indonesia (Ormas, pers. comm., 1993).
C. deburghiae represents a granulated form (Coomans et al., 1985b), C. nocturnus Hwass is a homonym and synonym of C. nocturnus [Lightfoot].

Range: Moluccas and N.W. New Guinea.
Habitat and Habits: In 1.5-2 m, on coral sand under rocks and on dead coral (Ormas, pers. comm., 1993).