Shell with b/l 0.38-0.41. a/l 0.27-0.33. anal sinus relatively deep and broad; whorls angular, with 2-3 strong spiral cords occupying basal half of each whorl, crossing short, broadly rounded axial ribs (13-15 per whorl), to form quadrate interstitial pits; shoulder slope smooth or with 4-6 feeble spiral threads; base of body whorl with somewhat nodular peripheral cord followed anteriorly by 14-17 very low spiral lirae; cream or pale yellowish-brown, flecked and blotched with brown, protoconch white with a brownish blotch next to tip; protoconch with first whorl bearing two weak spiral keels and faint axial ribs, 2nd whorl with about 14 strong axial ribs, protoconch diameter 1,15-1,25 mm. Attains 13,8 mm.
Description: Shell narrowly claviform (b/l 0.38-0.41, a/l 0.27-0.33) with high, orthoconic spire and blunt apex, base short, strongly contracted; teleoconch whorls about 6,25, suture shallow and slightly undulating; whorls angular, with periphery just below median, subsutural region broadly and somewhat shallowly concave, without a subsutural cord, left side of base of body whorl strongly concave, without a fasciole. Aperture ovately quadrate, with a medially squared labrum and short, open, strongly oblique siphonal canal, whose termination is not dorsally indented; base of columella convex, parietal region concave, labial callus very thin; labrum strongly convex in side-view, with a moderately deep, openly and asymmetrically U-shaped anal sinus, directed slightly adapically, but no stromboid notch.
Sculptured by strong spiral cords which occupy the basal half of each whorl, crossing broader but lower axial ribs, and forming quadrate interstitial pits, subsutural region with at most very weak spiral lirae; growth-lines coarse, somewhat pliculate. Spiral cords 2-3 per whorl, 3rd cord sometimes just showing above suture, at least on early whorls, and bordered anteriorly on body whorl by a 4th weaker and somewhat nodular cord; rest of base with about 14-17 very low spiral lirae, those on rostrum stronger but narrower; shoulder slope smooth or with 4-6 barely elevated but fairly broad spiral lirae. Axial ribs 13-15 per whorl, rapidly evanescing on base of shoulder slope and on body whorl at level of last suture, well-rounded, slightly opisthocline, somewhat wider than intervals.
Colour [near] pale orange-yellow to light yellowish-brown, flecked with brown, base of body whorl and sometimes intervals between ribs suffused with yellowish-brown, with an occasional very diffuse blotch of that colour on shoulder slope; protoconch white, with a comma-shaped brownish blotch next to tip.
Protoconch somewhat domed, of about 2 convex whorls (termination ill-defined), with rather deep suture; 1st whorl somewhat flattened but initially projecting sidewards, and bearing two weak spiral keels and traces of incipient axial ribs, giving the first whorl a somewhat malleate appearance; these ribs increase in strength and on 2nd whorl are strong, orthocline, arcuate and suture-to-suture and about 14 in number; breadth 1.15-1,25 mm, height 1,25 mm (b/h 0,92-1,00). Dimensions: 13,5 x 5,1 mm (holotype); 13,8 x 5,4 mm (paratype).

P. fenestratus differs widely from its three described congeners, notably in its well-developed anal sinus, strong axial ribbing and bicarinate protoconch nucleus.

Continental shelf of Natal and Zululand, 47-140 m.(South-Africa)