Shell large, length up to 276.3 mm, ventricose, ovate or globose, thin to slightly thick. Protoconch positioned below or above shoulder of last whorl. Teleoconch of 2,25-3 whorls. Shoulder of body whorl bearing a row of well separated, short and rather broad at base, nearly straight or somewhat curved spines, of 5-9 per whorl, length 8-17 mm. Early growth of spines from half to three quarters of first whorl, spines in mature shells terminating usually at outer lip or until last quarter whorl. Protoconch dome-shaped, of 3,25-3,5 whorls, spiral striae fine and radial striae coarse under suture, light brown or cream, apex whitish, diameter 12.6-13.4 mm, height 2.3-7.5 mm. Radial growth striae rather coarse, crossed with fine spiral striae. Colour uniformly light cream; baby shells generally have two rows of spiral brown spots, which rarely found on juvenile shells, and not found on adult shells. Occasionally two light brown spiral bands are faintly visible on last whorl in sub-adult shells. Aperture wide, semi-ovate or semi-circular, slightly wider anteriorly, posterior outer lip relatively flat. Interior light cream, occasionally orange near outer lip. Parietal wall and inside of aperture glossy. Columella arched, with three oblique plaits. Siphonal canal notch wide and deep, fasciole well defined. Periostracum thin, brown or light brown.
Type material. Tambelan Besar Island, Riau Archipelago, East Sumatra, Indonesia: Holotype MZB Gst. 12150, 259.4 mm. Pangandaran, West Java.

The shape of the shell, its relative thinness, the character of the few spines, and the monochrome light cream colour without spots distinguishes it from other Melo species. Both the interior and exterior colour of the shell are the same monochrome light cream. The shell colour of Melo nusantara n. sp. is a relatively monochrome light cream, similar to the ground colour of the shells of M. melo and M. tessellata. Most of the baby shells have two rows of spiral brown spots, only one in five juvenile shells (66.5-112.0 mm) that has two rows of spiral brown spots, all adult material examined has none. Sometimes the sub-adult shell has two light brown spiral bands that are faintly visible on the last whorl . The number of spines on M. nusantara n. sp. (5-9) is similar to that of M. umbilicatus (5-9), but the spines in M. nusantara n. sp. are smaller and shorter (8-17 mm) compared to the longer spines in M. umbilicatus (14-31 mm). The other distinguishing features are that the shell of M. umbilicatus is compressed, thick, the top protoconch is depressed to concave, the spire and protoconch are sunken, and the spine growth terminates at the outer lip. For differences between M. nusantara n. sp. and M. gajahmadai n. sp., see the discussion under M. gajahmadai n. sp. The holotype of M. nusantara n. sp. from Tambelan Besar Island, Riau Archipelago, East Sumatra, Indonesia was sympatric with M. melo and M. tessellata. Compared to M. aethiopicus which is usually globose in shape, the posterior outer lip extends upwards, has short and numerous spines (12-18). Compared to M. amphora which has thicker shells, sharp shoulder crests, and spines of adult specimens not reaching the outer lip.

Type locality. Tambelan Besar Island, Riau Archipelago, East Sumatra, Indonesia.
Distribution. Riau Archipelago, East Sumatra, between Sumatra and Kalimantan; Thousand Islands, West Java, Java Sea; Pangandaran, West Java, Indian Ocean; Cilacap, Central Java, Indian Ocean.
Habitat. On muddy sand, from fishing nets (liong bun net) and lobster nets to a depth of 80 m.
Etymology. Nusantara is another name for Indonesia, derived from the two words "ww.va" (island) and "antara" (between).