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Taxonomy
Clypeolum latissimum (Broderip, 1833)
Nomenclature
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Family: NeritidaeGenus: Clypeolum Récluz, 1842
SUMMARY
A moderately thin, lightweight shell with a flared and winged final whorl, thin lip, and a low spire. The spire is depressed below the final whorl and occasionally eroded. There are no spiral cords and only very fine axial growth striae, although large mature shells often have growth scars. The shell has a flat dull appearance with the periostracum intact and a glossy appearance without the periostracum. The aperture is large and generally gray to bluish with a dirty cream or light orange staining on the parietal shelf that darkens at the back of the shelf. This coloring seems to vary from north to south. Specimens from Mexico have a white or cream-colored parietal shelf, those from Panama have a yellowish tan coloring, and those from furthest south in Ecuador have a bright orange parietal shelf. The shell is moderately thin but thicker and not transparent as in Clypeolum owenianum (Wood, 1828). The parietal shelf is flat with a series of small riverine grooves extending back from the columella. The columella has an upper raised portion (apical end) and numerous minute teeth below this area, ending prior to the lower portion of the columella. There are no teeth on the outer lip. The operculum is dark gray or black with a light tan area around the nucleus that extends in an irregular thin band around the labral margin. There are very fine growth striae as well as an enlarged central area or broad spiral ridge from the nucleus to the position of the medial tooth. The apophysis is thin and flared with microscopic longitudinal grooves, and swept back at only 5°, but strongly curved outward from the opercular plain. There is no medial or lateral tooth, but there is a well-developed peg. There is also a brown corneous lamella along the labral margin of the operculum from the nucleus to the lateral terminus. This strip actually begins on the face of the operculum at the nucleus and completely covers the inner portion of the operculum with a thin periostracal layer. This layer is easily lost during cleaning or as the operculum dries out. The periostracum is thin and transparent and gives the shell a brown cast with a black pattern showing through. If the periostracum is removed the shell is gray, lavender, or pink, with a pattern of white tents outlined on the leading edge with black and superimposed on a series of wavy black axial lines. Occasionally the pattern forms into bands of grouped white tents or solid black.