Conus madagascariensis Sowerby II, 1858: 43, sp. 371, pl. 24, fig. 582 (three syntypes, BMNH (44 x 22; 42 x 23.5; 38.5 x 20.5 mm); " Madagascar ").

Material examined: MBMCS 136, 6 specimens, SL 42–68 mm; SW 18–29 mm.

Description. Shell medium sized to moderately large, moderately solid. Body whorl ventricosely conical to conoid-cylindrical; outline moderately convex at adapical third, straight below; left side often slightly concave near base. Aperture somewhat wider at base than near shoulder. Shoulder angulate. Spire low, outline slightly concave to slightly sigmoid, with a straight sided apex. Body whorl with weak spiral ridges on basal third.

Ground colour white, often variably tinged with violet, sometimes more prominently so at base. Body whorl with rather fine and regular network of dark brown lines edging numerous tiny to medium sized white tents. Overlying light brown to reddish brown spiral streaks, spots, flecks or blotches generally arranged in interrupted spiral bands on each side of centre and interspersed with spiral lines of alternating darker brown and white markings. Aperture white. Periostracum yellow, thin, translucent and smooth.

Distribution. Kohn (1978) first reported C. madagascariensis (as ‘ C. pennaceus Born’) from India, citing Hare Island, Tuticorin. He has also referred to a museum specimen (in BMNH) collected from there. C. madagascariensis is restricted to south India (Röckel et al. 1995).

The specimens reported herein were collected from Gulf of Mannar by trawling in 9–30 m around the fringe coral reef islands and a large number of specimens from Kanyakumari by trawling in 20–50 m (Table 6).

Remarks. Specimens of C. madagascariensis are often difficult to distinguish from C. pennaceus. However, the consistently straight-sided apex and rather uniformly reticulate pattern on the body whorl of C. madagascariensis distinguishes the latter. Although previously reported only from Tuticorin, during the three years of this survey not even a single specimen was encountered at Tuticorin.