Shell medium to large for genus (to 180 mm SL, average 108.3 mm SL, n = 60), angular fusiform. Protoconch damaged in all material examined; of approximately two whorls, less than 1 mm diameter, smooth, glassy. Axial sculpture of thick, rounded ribs that span sutures on early whorls; ribs becoming buttresses below shoulder in later whorls, reduced to vertical racks of knobs by body whorl. Spiral sculpture of three or four thick, rounded cords on early whorls, increasing to seven or more above suture on penultimate whorl. Spaces between cords with numerous axial growth lines on early whorls, lines becoming less definite in later whorls. Two dominant cords cross axial buttresses, the upper at periphery, giving distinctive double-noded appearance. Cords heavy and numerous below suture line on body whorl; thick, rounded major cords often interspersed with minors. One dominant cord on lower body whorl defines lower angle of profile. Cords may be broad and flattened in cross-section: axial sculpture on last half of body whorl often reduced to shoulder knobs. Suture adpressed; narrow subsutural band with numerous fine growth lines. Neck long, often strongly recurved in distal half, covered with characteristic sparse, thick spiral cords that persist to distal tip. Labral margin of aperture angulate; upper angle at shoulder, lower at terminus of lower dominant spiral cord. Labral wall of aperture smooth, glossy, with regular, fine spiral cords in pairs that join and terminate in developed teeth on labral margin; teeth correspond in position to troughs between external cords, and can be highly developed. Columellar margin of aperture smooth, glossy; parietal margin produced and slightly detached in adults: detached margin extends into upper part of canal. Canal long, open; labral margin thin, sharp, corrugated; corrugations are termini of spiral cords on outer surface. Shell white or ivory overall overlaid with pattern of dark brown to black blotches and dashes distributed randomly on spiral cords, with some brown axial flammules. Dark brown staining can be present on labral margin of aperture between teeth. Density and coverage of color pattern highly variable, from dense dark brown pattern over entire shell to isolated small patches and flecks. Interior of aperture and canal white.

Description. Callomon & Snyder (2007: 41) provided a modern description of F. nicobaricus which we modify here, adding details to facilitate comparisons with other species we place in this genus. Shell size medium to large for genus (to 189.1 mm SL, SCS, WLC), fusiform, with angular or rounded whorls, tall spire, swollen body whorl and long, slender siphonal process. Protoconch light brown to white, smooth, glassy, of approximately 2 whorls, diameter less than 1 mm; first whorl with rounded sides, flattened top, and immersed tip; second whorl little wider than first, with straight to convex sides; final whorl with 5-6 axial riblets extending from suture to suture before abrupt terminus. Teleoconch of up to 9 angulate or convex whorls; axial sculpture of thick rounded ribs spanning early whorls from suture to suture, becoming buttresses below shoulder on later whorls, reduced to vertical racks of knobs or absent on body whorl. Spiral sculpture of 3-4 thick, rounded cords on carly whorls, increasing to 7 or more on penultimate whorl; cords separated by narrow, deeply incised interspaces often containing single spiral thread; interspaces with numerous axial growth lines on carly whorls, becoming evanescent on later whorls; 2 dominant cords crossing axial buttresses at periphery, giving double-noded appearance to spire whorls; periphery sometimes reduced to one or two large undulant cords on body whorl; abapical half of body whorl and base usually bearing 7-8 large, broadly rounded cords separated by single threads, axial sculpture reduced or absent. Suture adpressed; subsutural band narrow, with numerous fine growth lines, cords of sutural ramp generally flattened. Siphonal process long, often recurved in distal half, covered with sparse thick transverse cords separated by single threads extending to tip. Aperture subovate, with rounded or subangulate labral margin; interior wall smooth, glossy, with paired fine spiral cords that join and terminate in developed teeth at labral margin; teeth corresponding in position to troughs between external cords; anal sinus small, formed by angle at top of sutural ramp and prominent callus on parietal shield; shield slightly detached, with thin, sharp margin extending into upper part of long, open, somewhat sinuous siphonal canal. External shell white to ivory or cream, overlaid with light to dark brown axial streaks and spots randomly distributed across spiral cords; dark brown color almost always present as streaks or spots atop or on sides of axial ribs or nodes on shoulder, sometimes present between teeth on labral margin of aperture; density and coverage of color pattern variable, ranging from densely streaked to nearly white shells. Interior of aperture and canal white. Operculum dark brown, drop-shaped, with terminal nucleus,outer surface bearing many closely-set concentric lines. Periostracum olivaceous, very thin. Radula (specimen USNM 824902, Okinawa, Ryūkyū Islands, Japan) formula 1.1.1. Rachidian subtriangular, widest anteriorly, with 3 slender, sharply pointed cusps, flanked by single shorter cusps on each side. Lateral teeth (Fig. 3) wide, base arched, produced markedly downward at outer lateral margin; cusps 11-13, straight, slender, pectinate, sharply pointed, arrayed fan-like with longest at center, diminishing toward lateral margins; outermost 2-3 cusps stouter, blade-like, slightly curved toward center; single tiny cusp at inner edge. Distribution. - Indo-West Pacific region: central Japan to Taiwan, South China Sea, Vietnam, Philippines, Papua- New Guinea, Indonesia, Thailand, and Sri Lanka. Remarks. We select Parigi, West Java, Indonesia as the type locality because we examined shells from there with markings and sculpture very similar to that of the shell that Chemnitz figured. Marmorofusus nicobaricus is the largest species of its genus. A 189.1-mm SL shell from the South China Sea was the largest specimen we examined, but a 197.3-mm SL shell from Japan was offered at an online auction several years ago. Syrinx nicobarica was described without a designated type locality. The name suggests that the species occurs at the Nicobar Islands between the Andaman Sea and the Bay of Bengal, and some early authors cited the Nicobar Islands or Bay of Bengal as its locality. However, the species was not mentioned by Subba Rao & Dey (2000) in their catalogue of marine mollusks of the Andaman and Nicobar Islands, and although we examined specimens from western Thailand and Sri Lanka, we saw none from the Bay of Bengal. Other authors followed Lamarck (1822: l'Océan des grandes Indes) and cited the locality as "East Indies." In 1869, Lischke cited records from Nagasaki and Manila, and more records from Japan and the Philippines followed for the next several decades. The name has been reported since from many other areas, but most of those records are of other species as indi- cated in the synonymy above. Marmorofusus nicobaricus is rather common in Japan, the Philippines, the South China Sea, and Indonesia, but its geo- graphic limits are poorly defined in the southeastern and southern parts of its range. In the southeast, the species is replaced by M. brenchleyi in New Caledonia. In Papua-New Guinea, Hinton (1972: pl. 16, fig. 9) figured as F.nicobaricus a shell from Manus Island in the Admiralty Group that seems to be correctly identified, and that record is supported by specimens we examined from New Britain and Woodlark Island, PNG. Papua-New Guinea is located on the northeast- em comer of the Australian continental shelf, but we saw no authentic specimens of M. nicobaricus from southeastern or northern Australia, where it appears to be replaced by two species that we describe hereafter. The shell figured by Cernohorsky (1972: pl. 48, fig. 3) as F. nicobaricus from "Qld., Australia" does not appear to be either of the Australian species and may indeed be M. nicobaricus, but it is not a very good photograph and the provenance of the shell is uncertain. Other citations of F. nicobaricus in Australia (e.g., Kaicher, 1957: 20, pl. 9, fig. 3) are too imprecise to verify. Finally, Hinton figured a shell that he identified as F. nico- baricus, first in a book on Papua-New Guinea shells (Hinton, 1975: 33, fig. 29), where he characterized it as uncommon, and then in a book on Australian shells (Hinton, 1978: 41, fig. 4), where he cited its range as tropical northern Australia. In both cases, the shell Hinton figured seems to be of a new species (described hereafter) from southeastern Australia, so we consider those citations unreliable. Shells of M. nicobaricus may be distinguished from those of congeners by greater size (-197 vs. 133, 114, 109 & 88 mm SL) and by dark markings on the sides or atop peripheral ribs or nodes; dark markings on shells of congeners occur between the ribs or nodes but not atop them. We observed four varieties of shell morphology and color that we include within M. nicobaricus. These varieties are loosely related to geographic distribution, but we caution that intergrades were seen between all forms; a form common in one region may occur less commonly in another, and no meristic measures were found to fully separate them. 1. Shells from central and southern Japan (Pl. 2, Figs 1-2) generally with peripheral nodes on all whorls but sometimes reduced or uncommonly absent on body whorl; irregular dark brown axial streaks usually accompanied by many thinner, lighter brown streaks, conferring overall brown hue to body whorl and siphonal process. Shells from Okinawa usually with peripheral nodes and strong, dark brown axial streaks on all whorls but lacking smaller brown streaks, leaving more white shell surface. 2. Peripheral nodes on body whorls of PI (Pl. 2, Fig. 3) and PNG shells usually prominent, rarely reduced or absent; dark brown axial streaks often broken into scattered brown spots, shells rarely nearly all white; spiral cords on body whorl and siphonal process well developed, two abapical cords on body whorl larger than others. PNG shells similar to PI form. Only one PI shell conforming to next form. 3. Shells from SCS, including Taiwan, Vietnam, Indonesia and Thailand (Pl. 2, Figs 4-7), with peripheral nodes on body whorl usually reduced or absent, producing rounded shoulder; spiral cords large, of subequal size, espe- cially prominent on abapical part of body whorl and siphonal process; dark axial streaks usually prominent, sometimes bro- ken into scattered spots. 4. Sri Lanka shells (Pl. 2, Fig. 8) generally more slender than PI or SCS forms, with well developed peripheral nodes. on all whorls and with large, subequal spiral cords on abapical half of body whorl; large, dark axial streaks accompanied by smaller streaks and blotches, especially on body whorl and siohonal process, rendering their principal color brown; shells resembling Japanese variety in color but with large, subequal cords of SCS shells.

Though variable in form and patterning. Marmorofusus nicobaricus is not easily confused with any other species in the northwestern Pacific. It can be readily distinguished by its angular profile, thick, highly developed spiral cords on the neck and pattern of dark brown spots, bands and flammules. It was placed in Fusinus when the paper on which this section is based was published (Callomon & Snyder, 2007) but has since been made the type species of Marmorofusus Snyder & Lyons, 2014.
Fusus laticostatus Deshayes, 1830 (described as laticostatus in the text, but misspelled laticosta on the plate) is often cited as a synonym of F nicobaricus, but the authors consider that the consistent morphological differences between it and all other forms of this species warrant treatment as separate pending further study. The type locality of F laticostatus is Sri Lanka, and examination of specimens in various collections (ANSP; MCZ; SC etc.) suggest that it is a separate species confined geographically to southern India and Sri Lanka (see Kirstisinghe, 1978: pl. 44, fig- 3).

This species has a very broad distribution in the Indo-West Pacific region, from central Japan to Australia and East Africa, including New Caledonia, the Philippines, Indonesia and Vietnam, and in certain areas it has to be distinguished from morphologically similar congeners. In Hawaii it is replaced by the similar M. michaelrogersi (Goodwin, 2001).