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Amalda oblonga (Sowerby, 1830)

Description: Shell moderately broad with body whorl expanded, aperture length two-thirds of total shell length.  Spire calloused, callus terminating in front of the aperture; suture concealed by callus.  Spire whorls smooth. Body whorl with calloused subsutural band at top, edged by deep groove.  Non-calloused part of body whorl with microscopic axial and spiral striae.  Columella pillar with about six very weak plaits; fasciolar band with central ridge or groove, upper and lower halves flat and smooth; ancillid band narrow, poorly defined, bordered above with an indistinct groove (not visible in figs. 1 & 2). Non-calloused area of body whorl fawn occasionally with axial zigzag streaks of brown; subsutural band white with axial brown flames; whole base of shell from above the ancillid groove, the ancillid band and both halves of anterior fasciole streaked or suffused with brown; pillar area white, sometimes suffused with brown.  Operculum brown, corneous.

Size: Length up to 28 mm.

Distribution: Endemic to Australia ; Moreton Bay , Queensland, to south-western Western Australia , including Tasmania .

Habitat: Subtidal, down to 150 metres.  Not taken alive intertidally, but common as a beach shell.

Comparison: This species is the most common of the genus as a beach shell around Sydney and in northern NSW; it is recognized by its two brown bands, sometimes accompanied by fine axial lines.  A. edithae, which has a similar colour pattern, is slender, deep water and rare in NSW.  A. festiva is similar to large specimens of A. oblonga, but the former occurs in deep water.  See A. marginata for comparison with that species.

Figs. 1,2: Gerringong, NSW (C.086226, both specimens)


Copyright Des Beechey 2004