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Austroliotia subquadrata (Tenison-Woods, 1878)

Description: Shell solid and heavy, wider than high, angled at shoulder and base. Last whorl of mature shells with five strong, usually nodular spiral ribs; one on shoulder, three on periphery, one wide and low on base bordering umbilicus; last quarter whorl of base with another spiral rib commencing at varix and merging with main base rib. About 20-25 axial ribs, sometimes of equal strength to spirals but usually weaker, either crossing or restricted to interspaces between spirals; fine axial lamellae between axial ribs. Aperture circular, surrounded by greatly expanded varix. Umbilicus narrow, deep, with axial lamellae within. Colour uniformly white or fawn.

Size: Up to 6 mm wide, 4 mm high.

Distribution: Endemic to Australia: Sydney, NSW, to southern WA.

Habitat: Known mainly from beach shells; also down to 60 m. Moderately common.

Comparison: Similar to A. botanica but differs in the following characters: five spiral ribs instead of eight; umbilicus narrow, with sharp angle of entry from base, as opposed to wide umbilicus with round entry; ribs on base just before varix merge. Much less common than A. botanica in NSW.

Remarks: The strength of the axial sculpture varies, sometimes crossing the spirals and forming nodules, otherwise being restricted to the interspaces so the spirals are smooth. The axials tend to fade out on the last quarter whorl.

Figs. 1,2,3:  Flinders, Westernport, Victoria (C.152101)


Copyright Des Beechey 2004