Description. Shell medium size for genus (to 133.4 mm SL), angular and fusiform, with 9-10 whorls; early teleoconch profile very slender, later whorls inflated. Protoconch unknown, damaged or missing on all specimens. Axial sculpture of ribs on early whorls, becoming irregular and skewed on later whorls; ribs replaced by peripheral band of prominent sharp knobs, with one or sometimes two additional bands of 10-11 less prominent knobs on body whorl. Spiral sculpture of very fine cords on adapical slope of shoulder; about 3 somewhat stronger cords on abapical side, each separated by single finer cord or thread; 6-7 low cords on adapical slope and about 13 cords on abapical portion of body whorl, strongest cord crossing knobs at shoulder, a somewhat lesser cord at posterior angle of whorl. Siphonal process long, slender, usually straight, bearing thick transverse cords persistent to tip, sometimes with weaker cords between. Aperture sub- ovate, labral margin planar, finely dentate, with about 20 teeth created by extensions of dorsal cords. Inner side of outer lip white, polished, with lirae terminating at teeth on lip. Anal sinus small, bordered by thick parietal callus. Parietal shield. polished, flaring, elevated and detached abapically, with thin, elevated margin extending into adapical part of canal; columella typically smooth. Siphonal canal partially closed, outer and inner edges nearly touching in adapical portion. External shell color creamy orange with irregular caramel marking; darker color found between peripheral knobs and on additional bands of knobs on body whorl; interior white. See Marais & Kilburn (2010: 118) for figure of operculum. Periostracum and radula unknown. Distribution. Natal Basin from Durban, Republic of South Africa, northward to southern Mozambique. Etymology. The specific name refers to the KwaZuluNatal region of South Africa, the principal range of this species. Remarks. Shells of M. natalensis spec. nov. most resemble those of M. brenchleyi, sharing with that specics prominent axial nodes on the periphery of whorls and large dark spots that separate those nodes. However, M. natalensis spec. nov. attains a larger size than M. brenchleyi (133.4 vs. 109.5 mm SL), other nodular cords on whorls of the spire and body are much more prominent, and the exterior markings, including spots between nodes, are caramel orange, not dark brown. Shells of M. natalensis spec. nov. differ from those of M. nicobaricus by having cords atop the body whorl more uneven in size, a large abapical cord there that is markedly nodulous, dark spots between but not atop the large peripheral nodes, and an orange or caramel primary shell color, not white as on M. nicobaricus. Specimens of M. natalensis spec. nov. are uncommon or rare (Steyn & Lussi, 2005; Marais & Kilburn, 2010), and locality records are few, most shells have been collected by offshore trawlers and divers. The three specimens accompanied by depth records include paratype 2 (40 m), paratype 3 (34 m) and paratype 5 (150+ m); Steyn & Lussi (2005) cited a depth range of 20-50 m for the species. A South African ex pisce record of F. oblitus by Boswell (1964) probably involved M. natalensis spec. nov. Fusinus oblitus (Reeve, 1847) is endemic to the Mascarenes (principally La Réunion), but its shell markings somewhat resemble those of M. natalensis spec. nov. Drivas & Jay (1988: pl. 27, fig. 6) figured as F. toreuma (Martyn, 1784) a shell from "La Réunion et de l'ile Maurice" that resembles M. natalensis spec. nov. A decade later, Drivas & Jay (1998: 36, fig. 7) illustrated the same or a similar shell as F. oblitus; in both cases they figured next to those shells a smaller, more typical F. oblitus for comparison. We withhold judgment on those records until we can examine material from the Mascarenes. Steyn & Lussi (2005) and Lussi & Stahlschmidt (2007) called this species Fusinus toreumus [sic; toreuma is a noun] Deshayes [in Deshayes & Milne-Edwards], 1843. Fusinus toreuma is based on a non-binominal name of Martyn (1784) and later validated by Deshayes who cited Martyn's figure. Martyn's figure was faithfully reproduced by Reeve (1847: pl. 7, fig. 27) and Tryon (1881: pl. 32, fig. 95). The shell is tall, narrow, with a long, slender, somewhat sinuous siphonal canal, and it lacks a subcarinate row of nodes separating the body whorl from the base, a feature of all Marmorofusus shells. Deshayes (1843: 67, 68) remarked, "Cette belle espèce a beaucoup d'analogic avec celle que M. Kiener donne comme le Nicobaricus [i.e., Fusus oblitus, which Kiener fig- ured as F. nicobaricus]. Nous avions même pensé que ces deux coquilles appartenaient à la même espèce; mais un examen plus approfondi nous a fait découvrir des caractères con- stans sur tous les individus. Le Fusus toreuma est une coquille allongée, étroite, qui se rapproche un peu du Fusus colus, mais qui est un peu plus venture". The F. toreuma figure does indeed resemble shells of F. oblitus, but some authors (e.g., Cernohorsky, 1972: 162) have continued to treat F. toreuma as a variety, and thus junior synonym, of Fusinus colus (Linnaeus, 1758). We withhold judgment on the name F. toreuma until more information is available, but clearly it is not appropriate for M. natalensis.