Cerithium africanum Houbrick 1992

Cerithium africanum

DESCRIPTION.—Shell (Figure 9): Shell turreted, reaching 22.9 mm in length, 10.1 mm in width, and comprising 11–13 straight-sided, anteriorly angulate, solid whorls sharply impressed beneath suture. Protoconch unknown. Early whorls cancellate with fine spiral cords and strong axial ribs. Adult whorls sculptured with 4 spiral cords, numerous fine spiral striae, and 10–15 axial ribs. Largest spiral cord abapical, spinose, with 11–14 pointed nodes; three, narrow, beaded, spiral cords above spinose cord. Sutural cords usually with more beads. Interspaces of main spiral cords with fine spiral striae. Spiny nodes on main spiral cord sometimes elongated into axial folds forming discontinuous ribs, weaker anteriorly. Suture deeply impressed, slightly wavy. Varices randomly distributed; largest varix opposite outer lip of aperture. Body whorl sculpture as in adult whorls, but with two large, closely spaced, smooth, occasionally beaded, spiral cords above siphonal constriction. Numerous fine spiral threads on siphonal constriction. Base of body whorl concave. Siphonal canal slightly reflexed, 45° to left of shell axis. Aperture ovate, about one–fourth shell length. Columella concave with narrow, distinct columellar callus and lip. Anterior canal elongate, tightly closed, reflexed to left of shell axis. Anal canal distinct, marked with parietal plate extending well into shell aperture. Outer lip thickened, convex, crenulate, with 7 paired, tiny, inner denticles, stronger in older specimens. Shell color white or dark brown, flecked with brown and tan, or with white spiral stripes of varying width. Shell measurements (Table 9). Operculum unknown.

Radula (Figure 10): Type-1 radular ribbon a little more than one-eighth the shell length, comprising about 66 rows of teeth. Rachidian tooth (Figure 10B) rectangular, with slightly concave anterior front Basal plate with slight median, posterior extension and pair of crescentic ridges. Cutting edge with large, central, pointed cusp flanked on each side by two small denticles. Rhomboidal lateral tooth (Figure 10B) with broad basal plate, long lateral-posterior projection, and large central ridge projecting posteriorly and bearing blunt denticle. Cutting edge with large, broad, pointed main cusp, one inner flanking denticle, and three outer flanking denticles. Small flange on anterior outer margin of lateral tooth. Marginal teeth (Figure 10A, B) with long stalks, rounded bases, and curved tips with spoon-shaped main cusps flanked with sharp denticles. Inner marginal tooth with two inner flanking denticles and one outer flanking denticle (Figure 10B). Outer marginal tooth same but without outer flanking denticles.

Anatomy: Unknown.

HOLOTYPE.—NM H1861, 22.9 × 10 mm (Figure 9D).

PARATYPES (5).—USNM 629034 (Figure 9E).

TYPE LOCALITY.—SW Conducia Bay, NW of Choca, Mozambique; in muddy sand near rocks, intertidal.

ETYMOLOGY.—This species, endemic to eastern Africa, is named after that continent.

Cerithium africanum is a species of sea snail, a marine gastropod mollusk in the family Cerithiidae.