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Tatea Tenison-Woods, 1879

Diagnostic features

Shell small (up to 6 mm in length), females tending to be larger than males, elongate conic, solid, non-umbilicate, spire outline straight to slightly concave, periphery subangled to convex in adults, angled or ridged in juveniles. Protoconch of 2 whorls, protoconch I of c. 1 whorl, surface covered with minute, shallow, irregular pits; protoconch II smooth or with fine spiral periostracal ridges. Teleoconch smooth except for faint growth lines and subobsolete spiral sculpture. Aperture oval, non-varicose, with thickened, sometimes red or orange, peristome, outer lip with sharp edge, thickened within, inner lip thickened. Periostracum dark brown, smooth. Operculum flat, oval, rather thick, with 2-10 (usually about 5) well-developed pegs arising from white smear. Radula taenioglossate; central teeth with 3 conspicuous basal cusps. Head with long, tapering cephalic tentacles with ring of black pigment in distal third to quarter of each tentacle; each tentacle with well developed ciliated strips mid-dorsally, dorsolaterally on their inside edges and ventrolaterally; 5-9 small ciliated folds on outer (posterior) edge of left tentacle.

Classification

Class Gastropoda

Subclass Caenogastropoda

Order Littorinimorpha 

Superfamily Truncatelloidea

Family Tateidae

Genus Tatea Tenison-Woods, 1879

Type species: Bythinia huonensis Tenison-Woods, 1876

Original reference: Woods, J. E. Tenison  (1879). On some Tasmanian freshwater univalves. Papers and Proceedings of the Royal Society of Tasmania 1878: 65-72.

Type locality: Huon River, Tasmania.

Biology and ecology

Found in estuaries and coastal lagoons, particularly in mangroves, usually high on the shoreline where it is often found under litter and herbs.  Often abundant. Egg capsules small (0.30-0.36 mm in maximum diameter), hemispherical, covered with minute 'sand' grains; containing single egg. Development via a swimming veliger larva.

Distribution

Southern Western Australia to southern Queensland.

Notes

Tatea differs from other tateids in having the following combination of characters: a protoconch of two whorls consisting of protoconch I and II (not about 1.3-1.7 whorls with no protoconch 11), a black pigment ring around the distal end of the cephalic tentacles, and the female genital opening located beneath the middle of the capsule gland. It differs from nearly all in having more massive opercular pegs and a thicker operculum. In addition, Tatea has several small ciliated folds on the left cephalic tentacle, a feature that is absent in related freshwater taxa.

Further reading

Beesley, P. L., Ross, G. J. B. & Wells, A., Eds. (1998). Mollusca: The Southern Synthesis. Parts A & B. Melbourne, CSIRO Publishing.

Ponder, W. F., Colgan, D. J. & Clark, G. A. (1991). The morphology, taxonomy and genetic structure of Tatea (Mollusca: Gastropoda: Hydrobiidae), estuarine snails from temperate Australia. Australian Journal of Zoology 39: 447-497.

Ponder, W. F., Clark, S. A. & Dallwitz, M. J. (2000). Freshwater and estuarine molluscs: an interactive, illustrated key for New South Wales. Melbourne, CSIRO Publishing.

Robinson, K. & Gibbs, P. (1982). A field guide to the common shelled molluscs of New South Wales estuaries. Sydney, Coast and Wetlands Society.