Typhlosyrinx pyrropelex: Shell smooth, polished. Protoconch 3½-4 whorls, last 2 or 3 whorls with regular oblique (protractive) pliculae, becoming slightly sigmoid near junction with 1st postnatal whorl. Postnatal whorls 6½ (7); profile convex, with slight shoulder. Growth-lines strongly sigmoid, irregularly pliculose near the suture, becoming strongly protractive (nearly horizontal) on the shoulder, and forming in some specimens obscure rounded axial rips below shoulder on 3rd and 4th whorls, c. 14 on 4th whorl, best seen as marginal undulations in apical view. Fine indistinct spiral striae below shoulder, c. 5-6 on 2nd whorl, 7-8 on 3rd, 8-9 on 4th, increasing to c. 25 on 7th whorl, on base 25-30 on 4th whorl, 50-66 on 7th. Juveniles: up to 22,5 x 9 mm. (4 whorls). Creamly-white, glossy, protoconch fulvous brown. No operculum.
Animal pale; eyes represented by a minute pigment speck or absent. Radula (juveniles) with 25-30 pairs of slender doubly-barbed teeth, with a projecting knob proximally.

Largest syntype (49.3 x 18.5 mm at 7 teleoconch, 15 preserved protoconch whorls) with slightly broken canal eroded parts of bodywhorl. Another syntype (SAM A1645, 45.0 x 15.3 mm) strongly eroded, with broken aperture. Largest of two remaining syntypes designated here as lectotype. Shell 48,2 x 17,2 mm, white, thin, fragile. Protoconch of 1.5 preserved brown whorls with thin oblique arcuate axial riblets. Ribs more crowded and irregular near the transition to teleoconch, less inclined, occasionally bifurcating in lower part. Teleoconch whorls (6.8 in number) almost evenly rounded, with well-marked subsutural ramp, slightly concave in early whorls, almost flat in last ones. Border of subsutural ramp defined by shallow groove. Some growth lines on subsutural ramp thickened below suture, which is more pronounced in early whorls. Subsutural ramp devoid of spiral sculpture except for indistinct striatum on its lower part, Spiral sculpture be¬low shoulder consisting of very low, flattened, wide, slightly wavy cords with serrated edges, separated by narrow grooves. Cords becoming stronger, narrower below body whorl periphery. Based on growth lines, the anal sinus subsutural, wide, deep. Its margin almost vertical below suture, nearly horizontal at border of subsutural ramp. Outer lip very strongly projecting forward below sinus. Paralectotypes very similar to lectotype, varying insignificantly in details of spiral sculpture, None have more intact protoconch than on lectotype.

The species has all the essential characters of Xanthodaphne Powell, 1942. Protoconch sculpture is similar to that of the type species of the genus, Pleurotoma membranacea Watson, 1886. However, the shell of X. pyrropelex is more slender than that of most other representatives of the genus. Xanthodaphne pyrropelex species was also recorded in the area from 33°36'S to 3 4°36'S and from 16°15'E to 17*00''E, at 2524-3219 m (Barnard, 1963).