Cerithium abditum Houbrick 1992

Cerithium abditum

DESCRIPTION.—Shell (Figure 6A,C–G): Shell small, thin, porcelanous, turreted, reaching nearly 15.4 mm length and 4.5 mm width, comprising 14 or 15 moderately inflated whorls. Protoconch (Figure 6D) brown, comprising 4.5–5 whorls and with deep sinusigeral notch. Protoconch I smooth; protoconch II sculptured with spiral, subsutural plications and two spiral bands, first of which slightly beaded. Minute pustules on base of last protoconch whorl (Figure 6D). Teleoconch sculptured with 3 beaded spiral cords; weakest cord subsutural; remaining 2 spiral cords becoming progressively stronger anteriorly. Spiral cords crossed by 12–14 axial ribs on penultimate whorl (Figure 6E,G). Axial sculpture dominant, with opisthocline ribs; beads aligned with ribs where crossing spiral cords. Beads sometimes slightly pointed and facing shell apex (Figure 6E,F). Early whorls (Figure 6F) with fewer ribs and spiral cords. Suture impressed, slightly wavy. Body whorl broad with large varix. Body whorl sculpture same as penultimate whorl, but with two smooth spiral cords and several thin, weak spiral cords on siphonal constriction. Varices randomly distributed; largest varix opposite outer lip of aperture. Aperture ovate, a little less than one–fourth the shell length. Columella concave and with very weak callus. Anterior canal moderately long, slightly reflected upwards and left of shell axis. Anal canal weak. Outer lip rounded, slightly crenulated or wavy. Measurements (Table 8). Periostracum thin. Operculum (Figure 6B) corneous, circular–ovate, paucispiral and with subcentral nucleus. Free surface of operculum covered with minute scales.

Radula (Figure 7): Type–4 radular ribbon (Figure 3D) very small, about one–tenth the shell length, comprising about 20 rows of teeth. Rachidian tooth (Figure 7B, D) rectangular having flat basal plate with slight ventral extension; cutting edge with pointed central cusp flanked on each side by two small denticles. Lateral tooth (Figure 7B) rhomboidal having short basal–lateral extension, weak inner buttress, and weak median, transverse peg on broad basal plate; cutting edge with single, pointed, inner denticle, large, pointed cusp, and 5 or 6 pointed, outer denticles. Marginal teeth (Figure 7C) long, spatulate, curved at distal ends, and with long, pointed tips flanked by thin, needle–like denticles. Tips of inner marginal tooth serrated with four, sharp, inner denticles and five, sharp, outer denticles. Outer marginal tooth same, but lacking outer denticles.

Anatomy: Soft parts unknown except for pair of tiny, thin, semilunar–shaped jaws with scale–like surface.

HOLOTYPE.—USNM 286404, 15 × 4.2 mm (Figure 101A).

PARATYPES (5).—USNM 860482.

TYPE–LOCALITY.—Off Simaluc Id, Tawitawi, Philippines, 554 m.

ETYMOLOGY.—From the Latin abditus (hidden, concealed).

ECOLOGY.—This species lives in deep water, to a depth of 987 m, on sand and rubble bottoms. The many whorled, sculptured protoconch (Figure 6D) indicates a planktotrophic larval stage in life history. It appears to be a common species, and has been dredged in large numbers at some stations.

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