Neritids of the genus Neritina and similar genera such as Vittina have cap-shaped, globular, or semiglobose, shells with a low- to flat spire that is often submerged by last whorl. The surface is generally smooth, sometimes with spines. The periostracum is usually thick or at least well-developed. Colour may vary from black to multi-coloured, often with distinct and complex colour patterns. Columella very pronounced, broad and shelf-like, sometimes with wing-like projections, and often brightly coloured; columellar edge smooth or with fine denticulations. There is no umbilicus. The operculum is ‘D’-shaped with a smooth glossy outer surface, often spirally patterned, with a prominent internal often bi-lobed elongated peg (apophysis) and a low internal spiral raised area or bulge mid-way. Their cephalic tentacles are narrow with the eye situated on a short stalk next to the outer edge of the tentacle. The snout is short and truncated with a scalloped edge. The spermatophores are variable in length, with or without an enclosing envelope or an internal radial thread but never with an external filament. Vaginal duct long and leaves the vagina near the spermatophore sac. Penes are variable but generally an external long curved organ with a prominent lateral or terminal groove; there is never a penis pouch in the male head.
Vittina variegata is a rather medium-sized species (length to about 27 mm) has variably coloured shell with dark wavy lines and a pale yellowish to white aperture. The spire is moderately raised. The operculum is externally black. A similar species, V. lugubris (Philippi, 1843) has a pale brown operculum and lives together with V. variegata in the brackish parts of rivers and streams.
Vittina variegata (Lesson, 1830)
Class Gastropoda
Infraclass Neritimorpha
Order Neritopsida
Suborder Neritina
Superfamily Neritoidea
Family Neritidae
Subfamily Neritininae
Genus Vittina H. B. Baker, 1924 (Type species Nerita roissyana Récluz, 1841) (Synonym Paranerita Bourne, 1908, preoccupied)
Original name: Neritina variegata Lesson, 1831. In Lesson R. P. (1831). Chap.XI. Mollusques, Annelides et Vers. pp.239 - 471 in, Voyage Autour du Monde Execute par Ordre du Roi, sur la Corvette de Sa Majeste, La Coquille, pendant les annees 1822, 1823, 1824 et 1825. Zoologie. Paris: Bertrand Vol. 2(1).
Type locality: New Ireland.
On rocks in running water in streams and rivers. Can also occur in the upper estuarine parts of rivers. As with other neritids, egg capsules are small, oval and white.
Tropical northern Australia. Also, SE Asia, some larger Pacific Islands and Papua New Guinea.
Beesley, P. L., Ross, G. J. B. & Wells, A., Eds. (1998). Mollusca: The Southern Synthesis. Parts A & B. Melbourne, CSIRO Publishing.
Davis, A. R. & Ponder, W. (2019). Biogeographic conundrum: Why so few stream nerite species (Gastropoda: Neritidae) in Australia? Freshwater Biology 64: 2084-2088.
Haynes, A. (1988). Notes on the stream neritids (Gastropoda: Prosobranchia) of Oceania. Micronesica 21: 93-102.
Benthem Jutting, W. S. S., van (1956). Systematic studies on the non-marine Mollusca of the Indo-Australian Archipelago. 5: Critical revision of the Javanese freshwater gastropods. Treubia 23: 259-477.
Smith, B. J. (1992). Non-marine Mollusca. Pp. i-xii, 1-408 in W. W. K. Houston. Zoological Catalogue of Australia, 8. Canberra, Australian Government Publishing Service.
