Shell elongate-fusiform, up to 29 mm in length; width 34-38% of shell length in adult specimens (width up to 45% of length in immature/subadult specimens). Protoconch formed like a truncated cone, involute-paucispiral, with 2.0-2.5 glossy, rounded, beige coloured embryonic whorls. Teleoconch up to 8 whorls; whorls not angulate at the sutures which are rather indistinct, narrowly ledged; side lines of spire slightly concave, spire whorls flat-sided; first 2-3 post-nuclear whorls with 3 prominent spiral cords, later spire whorls with 4 spiral cords, the 4th spiral being more slender; last part of penultimate whorl occasionally with an additional 5th slender spiral cord; body whorl with 11 prominently elevated spiral cords (apart from the siphonal fasciole), first 3 spirals below the suture being strong and rounded, the remaining 8 spirals are more slender and rather widely spaced; the interspaces between the spiral cords are deeply concave and axially lamellate. Aperture slightly shorter to slightly longer than the spire (aperture length 46-53% of total shell length); outer lip only slightly thickened in fully mature specimens, crenulate in accordance with the highly elevated spiral cords and deeply concave interspaces; inner lip only developed in fully mature specimens (e.g. paratype No. 16 from Vietnam). Columella with 4-5 oblique folds which decrease strongly in size anteriorly; siphonal fasciole with 5-7 densely arranged oblique cords; siphonal notch moderately wide and rather shallow, siphonal canal short and only slightly recurved. Shell ground colour strawberry-red or dark crimson to ruby-coloured, ornamented with regular white spiral streaks on the ridges of the spiral cords, except a light coloured peripheral zone of the body whorl where the 4th to 6th spiral cords of the body whorl (counted from the suture) are white and ornamented with regular red spiral streaks on their ridges. (Only in few subadult specimens these red streaks on the ridges of the spiral cords within the light coloured peripheral zone are lacking or only faintly visible.) Siphonal fasciole also strawberry-red, mottled with white; aperture and colu-mella reddish to beige.

Pseudonebularia gracilefragum n. sp. has mainly been confused with M. (Nebularia) lienardi Sowerby, 1874 (Figs. 18-19; see also Cernohorsky 1976a: 399-400, pi. 336, fig. 5, showing the probable holotype of Pseudonebularia lienardi ANSP 28725: 24.2 x 8.6 mm). From P. lienardi the here described P. gracilefragum n. sp. differs in the following characters:
1) The shell shape is elongate-fusiform (not elongate-ovate as in P. lienardi);
2) the side lines of the spire are slightly concave (not convex to straight as in P. lienardi);
3) the shell base is more contracted and elongate;
4) the shell is without axial folds;
5) 11 spiral cords on body whorl (13-14 in P. lienardi);
6) the spiral cords on the body whorl are prominently elevated from deeply concave axially lamellate interspaces (whereas in P. lienardi the spiral cords are more rounded with axially finely striate interspaces);
7) the (three) spiral cords within the peripheral light coloured zone in most specimens show regularly arranged and comparatively very narrow red streaks approximately equal in length as the alternating white interstices (a character not found in P. lienardi);
8) the lower part of body whorl including siphonal fasciole is red, mottled with white (not with a uniformly light coloured siphonal fasciole as in P. lienardi).
P. gracilefragum n. sp. has also been confused with P. fraga Quoy & Gaimard, 1833 although this species differs in having an ovate-bulgy shell shape, its whorls are angulate to subangulate at the sutures, its aperture is definitely longer than the spire, and the colour pattern of the body whorl lacks the whitish peripheral zone with red streaks on the 4th, 5th and 6th spiral ribs so peculiar and typical for P. gracilefragum n. sp.
P. gracilefragum n. sp. resembles in shape and general aspect to some degree also Pseudonebularia dovpeledi Turner, 1997, from the Red Sea. This species may be confidently distinguished as its spiral cords and grooves on body whorl remain the same in relief, width and colour pattern
from the suture to the base, and — even more noticeable — its shell ground (including the interior of aperture) is not red in colour (as in P. gracilefragum n. sp.), but white.

Type locality:
Calituban Island north of Bohol, central Philippines, in shallow to moderately deep water.
Distribution and habitat:
Tropical Indo-Pacific (Maldives, Indonesia, Vietnam, Philippines, Okinawa, Papua New Guinea, Solomons, Marquesas Islands). From fairly shallow subtidal water (8-20 m) to deep water (180 m), on bottoms of sand and coral rubble.