Shell large, maximum height 68.2 mm (ANSP 349402, Puerto Rico), variable in shape (diameter/shell height, 0.48-0.74); whorls usually with two distinct upper angulations, one at shoulder and the other marked by central cord; other spiral sculpture of last whorl usually fine, consisting of four to ten threads on subsutural ramp, five or more cords or many fine threads between the two angulations, and four or more cords or fine threads on base and siphonal canal; axial sculpture consisting of seven to 14 rounded ribs, usually forming tubercles or nodes at upper angulation, weakening adapically toward suture and abapically toward lower angulation, and absent on base; outer lip medially convex, with distinct labral tooth at end of central cord, and with well-developed subsutural sinus above upper angulation; lirae beaded, weakly expressed; aperture height / breadth, 2.4-3.0; siphonal canal comprising 18-52% of total apertural height; siphonal fasciole distinct; umbilical slit usually absent; shell externally chestnut-brown, with white spiral band corresponding to central cord ending in labral tooth; aperture white to peach-colored; soft parts bright red. Hutsell et al. (2001:53) report an 82.0 mm specimen from Brazil; we have been unable to verify this record.

The typical form of L. nassa occurs on Caribbean islands from Puerto Rico and the Windward and Leeward Islands to Curacao and Aruba. It has a moderately broad to very broad shell (diametenshell height, 0.645 ± 0.039, n - 22; range, 0.57-0.71) with a relatively low spire (aperture height: total shell height, mean 0.66 ± 0.041, range 0.58-0.72). There are usually two or three strong cords at and just below the upper (shoulder) angulation, and one or more enlarged basal cords. In addition, spiral threads cover the entire shell surface. The aperture is white. The siphonal canal is relatively long (canal height / total aperture height, mean 0.41 ± 0.05, range 0.31-0.52). Adult size varies greatly from place to place. The largest specimen we have seen is a 68.2 mm high shell from Puerto Rico (ANSP 349402).

As Latirus cinguliferus:
Shell solid, with a moderately developed spire and having about eight whorls. The form and sculpture of the whorls vary remarkably. In some cases there is a revolving row of strong tubercles on the middle of the whorls, which forms a well-marked shoulder on the body whorl; in other cases the shell is absolutely destitute of nodules and the whorls are slightly rounded, and there is every possible variation between these extremes. The growth lines are strong and irregular, and the surface is covered with faint, revolving threads, so that it is more or less reticulated. The aperture is elliptical; the outer lip is generally lirate within, though sometimes it is nearly smooth. Above the base there is usually a sort of revolving ridge which ends in a small tooth or projection on the outer lip. The canal is rather short and recurved; the columella bears about four faint plaits, and the shell is often falsely umbilicate at its base. Color light brown to nearly black. There is generally a narrow, white band on the ridge just above the base.
Length, 65 mm.; diameter, 30 mm.

Leucozonia jacarusoi: Petuch (1987) named Leucozonia jacarusoi on the basis of several subadult shells from a probable depth of 70 m off Key West, Florida. He distinguished L. jacarusoi from L. nassa by its pale color and the absence of the characteristic white band in L. jacarusoi. We have examined the holotype (USNM 859910) and a second specimen (SC). These specimens do not differ morphologically from subadult individuals from elsewhere in Florida, nor from the 16.3 mm high specimen from North Carolina that represents the northernmost record of L. nassa (USNM 843133). The shells of L. jacarusoi are slender (diameter /shell height, 0.54 and 0.55) and high-spired (aperture height / total shell height, 0.63 and 0.67). The last whorl is sculptured by ten to 11 spiral threads on the subsutural ramp, 11 cords on the central sector including a slightly enlarged cord at the shoulder angulation and a slightly enlarged central cord, seven basal cords of which two are slightly enlarged, and nine to 11 axial ribs. The holotype lacks a labral tooth. We therefore agree with Rios (1994) that L. jacarusoi is a synonym of L. nassa. If the Floridian population should turn out to be genetically distinct, however, the name L. jacarusoi Petuch, 1987 is probably the name that should be applied to it.

Leucozonia nassa as defined here is a widespread, geographically variable western Atlantic taxon distinguished by usually fine spiral ornament, distinct axial ribs, usually a row of nodes at the shoulder angulation, fine beaded lirae on the inner side of the outer lip, and a labral tooth. No other species has this combination of characters. L. leucozonalis, which mostly occurs in the northwestern Caribbean outside the range of L. nassa, typically lacks axial ribs and shoulder nodes, and its spiral sculpture on the convex part of the adult last whorl is obsolete. For other comparisons see remarks under L. ponderosa, L. triserialis, and L. ocellata.
A large, extremely thick-shelled form with a peach-colored aperture occurs in offshore Brazilian waters. We have seen specimens from Fernando de Noronha, Atol das Rocas, Bahia, and Trindade. Spiral sculpture consists of very weak cords or obsolete threads. Axial sculpture is also weakly developed, and in some specimens from Fernando de Noronha and the Abrolhos Islands is absent on the last whorl. Shell shape overlaps with that of typical L. nassa (diameter / shell height, mean 0.625 ± 0.055, n = 9, range 0.57—0.74; aperture height / shell height, mean 0.615 ± 0.053, range 0.54-0.67). The siphonal canal is relatively short (canal height:aperture height, mean 0.30 ± 0.07, range 0.18-0.36). In two specimens from Fernando de Noronha (VC), the canal is very short (canal heightraperture height, 0.18 and 0.21), and the last whorl lacks the upper and lower angulations as well as tubercles. This form therefore closely resembles L. leucozonalis from the western Caribbean, and it may well represent an endemic species (see Vermeij, 1997). The typical nodose Brazilian form of L. nassa also occurs at Fernando de Noronha. Two specimens (BMNH 1858.6.27.18-19) described and illustrated by Smith (1890) from Fernando de Noronha as Leucozonia cingulifera are intermediate in sculpture be¬tween the smooth and nodose types.

Off North Carolina (33°32' N, 77°24' W, 28 m) (USNM 843133) to both sides of Florida; Bahamas; north coast of Cuba; south coasts of Hispaniola and Jamaica; eastern Caribbean from Puerto Rico to Trinidad and Barbados; Veracruz, Campeche, and western Quintana Roo, Mexico; coast of Central and South America from Costa Rica to Baia de Guaratuba, Santa Catarina, Brazil (Marcus and Marcus, 1962); Brazilian islands of Fernando de Noronha, Atol das Rocas, and Trindade.