| Since 1985, two species (Ampularia levior Sowerby and A. gigas Spix) belonging to the genus Ampullaria, have been found in several areas in the northern part of the New Territories of Hong Kong. The present paper reports briefly on the morphological characteristics of these two species. Measurements of 10 specimens of each species are shown in Table 1 and Table 2. The shell morphology of these two species is shown in Plate I: 1&5 and the morphology of their radula obtained by scanning electron microscopy is shown in Plate I: 2 - 4, 6 - 8.
Ampullaria levior Sowerby, 1909 (pl. I: 1 - 4)
Ampullaria levior Sowerby, 1909: 361 - 362, with text figure.
Alderson, 1925: 27 - 28, pl. VIII, fig. 7, 8.
Shell conico-oval form, 5 - 6 round-convex whorls, dark yellowish brown in color with many dark spiral bands, some may also have longitudinal plicatae or transverse lirae; spire high and expanded, apex prominent, sutures rather shallow; body whorl high, its shoulder slightly oblique; aperture widely expanded, lip acute; umbilicus present; operculum corneous, eccentric type with prominent growth ring, nucleus closer to the inner lip.
Radula fonnula: 7 - 3 - 2 - 2 - (pl. I: 2).
Habitat: Amazon River.
Ampullaria gigas Spix, 1827 (pl. I: 5 - 8)
Pomacea maculata Perry, 1810 (Arcana).
Ampullaria gigas Spix, 1827: 1, pl. I, fig. 1; Reeve, 1856, fig. 3; Hupe, 1857: 64; Sowerby, 1909: 350; Alderson, 1925: 22 - 23, pl. VII, fig. 3. A. gigantea Tristram, 1863: 414.
Shell large, oval form, 4 - 6 whorls, thinner, more brittle and flattened than A. levior, light yellowish brown to olive green tinge in colour, traces of malleation in old specimens; spire lower, apex flatter, sutures deeper than A. Ievior; body whorl highly dominant; aperture ovaloid, lip sharp; with greater variation in shell morphology than A. levior; umbilicus large; operculum comeous, regularly concentric with fine growth rings, nucleus eccentric and closer to the collumela.
Radula formula: 7 - 4 - 2 - 2 - (pl. I: 6).
Habitat: Amazon River. |
