Cerithium egenum Gould 1849

Cerithium egenum Gould, 1849

Cerithium egenum Gould, 1849:121 [holotype: USNM 5571; type locality: “Wilson's Id” (Manihi, Tuamotus); 6mm×2.5 mm];—1852:151, pl 10: fig. 17.—Sowerby, 1865, pl. 15: fig. 101 [not Cerithium egenum Gould, 1849].—Tryon, 1887:137, pl 25: fig. 70.—Kobelt, 1898:243, pl. 42: fig. 13 [not Cerithium egenum Gould, 1849].—Kay, 1979:121, fig. 45G.

Cerithium rarimaculatum Sowerby, 1855:875, pl 183: fig. 204 [holotype: BMNH 1975625; type locality: Debu, Philippues; 11 mm]; 1865, pl. 15: fig. 103.—Tryon. 1887:139. pl 26: fig. 91.—Kobelt, 1898:216, pl. 38: fig. 9.

Cerithium strictum Hedley, 1899:433–434, fig. 22 [holotype: AMS C5942; type locality: Funafuti Atoll, Elllice Islands, 7 mm × 3 mm].

Cerithium bavayi Vignal, 1902:304, pl. 8: figs. 7, 8 [holotype: MNHNP, no number, type locality: New Caledonia; 9.7 mm × 1 m].—Cernohorsky, 1972:69, pl. 15: fig. 9 [in part, right hand figure only].—Salvat and Rives 1975:270, fig. 68.

Cerithium bavayi var. denticulate Vignal, 1902:305 [holotype: MNHNP; type locality: New Caledonia; not Cerithium denticulatum Lamarck, 1804].

Cerithium (Conocerithium) egenum Gould.—Maes, 1967:113, pl. 6: fig. K—Ladd, 1972:39, pl. 9: figs. 9, 10.

Cerithium (Conocerithium) bavayi Vignal.—Cernohorsky, 1972:69, pl. 15: fig. 9 [in part, right hand figure only].

Cerithium (Thericium) egenum Gould.—Rehder, 1980:37, pl. 6: fig. 4.

DESCRIPTION.—Shell (Figure 55): Shell small, narrow, turreted, comprising 9–11 weakly inflated, sometimes angulate adult whorls, and reaching 11.5 mm length and 4.8 mm width. Protoconch (Figure 55K) of 3 whorls; protoconch 1 smooth; protoconch 2 with elaborate sculpture and sinusigeral notch. Protoconch sculpture comprising two spiral cords, subsutural, colabral, axial plaits; minute opisthocline axial plaits beneath first spiral cord, and presutural, orthocline, axial riblets beginning before and crossing over second spiral cord. Early whorls (Figure 55B) sculptured with 5 or 6 spiral cords, incised spiral striae, and tiny spiral threads. Central spiral cord enlarging on successive whorls. Adult teleoconch sculptured with 5–7 raised, flat-surfaced, unequal, spiral cords and incised spiral lines. Subsutural and central spirals sometimes with up to 13 beads becoming angulately nodose at periphery. Minor spiral cords sometimes pustulose. Suture slightly impressed, distinct Body whorl elongate, concave subsuturally, becoming convex adapically, with moderately excavated base and with prominent varix opposite outer lip of aperture. Body whorl sculptured with numerous spiral cords and striae, angulate at center and with central spiral band of subsutural beads or nodes. Aperture ovate, about one-third the shell length. Columella concave, with slight columellar callus and weak parietal plait defining anal canal. Anterior siphonal canal very short, turned to left of shell axis. Outer lip smooth. Shell color white with axial chestnut-brown markings on base; sometimes with irregular brown blotches or spirals on upper whorls. Measurements (Table 20). Periostracum light tan, thin. Operculum thin.

Radula (Figure 56): Type-1 radular ribbon (Figure 3A) long, about one-half the shell length. Rachidian tooth (Figure 56B) triangular with rounded sides, pair of fine posterior ridges, and narrow, triangular, posterior extension; cutting edge with large, pointed, central, main cusp flanked on each side by two sharp denticles. Lateral tooth (Figure 56B) with long lateral, posterior extension, and with broad, central, basal buttress bearing weak central pustule; cutting edge with large, pointed main cusp, one inner flanking denticle and 3 or 4 outer flanking denticles. Marginal teeth (Figure 56A,B) spatulate, with curved spoon-like, serrated tips. Inner marginal tooth with long main cusp, 4 inner flanking denticles and 2 or 3 outer flanking denticles. Outer marginal tooth same, but without outer flanking denticles.

Anatomy: Animal whitish yellow with yellow spots on head, cephalic tentacles, and sides of foot Dorsal-posterior part of snout and cephalic tentacles, especially peduncles, dark brown, and sides of foot with brown blotches. Sole of foot with yellow spots and with deep anterior pedal mucus gland. Snout moderately elongate. Mantle edge with short yellow papillae and roof of mantle at inhalant siphon darkly pigmented, thickened, and folded where ctenidium ends.

Osphradium wide in proportion to ctenidium, flesh-colored, extending length of ctenidium, but separated from it by thin area of mantle, and turning sharply away from ctenidium at inhalant siphon. Ctenidium narrow, grayish yellow with black edges, comprised of long, triangular filaments. Hypobranchial gland with gray papillate texture, partially covering rectum; very wide, swollen near anus. Inner mantle adjacent to anus and distal end of pallial gonoduct black.

Buccal mass comparatively large with pair of large jaws. Paired salivary glands originating behind nerve ring as swollen masses, passing through it, uncoiling, and emptying on upper anterior surface of buccal mass. Esophageal gland present.

Type-B palliai oviduct (Figure 4B) with anterior white capsule gland and posterior albumen gland. Posterior seminal receptacle near edge of inner side of spermatophore bursa and connected by narrow duct along edge of medial lamina to anterior sperm gutter. Anterior seminal receptacle of lateral lamina a small, anterior, narrow pouch.

SYNONYMIC

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