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Amalda petterdi (Tate, 1893))

Description: Shell varies  from slender to moderately broad, aperture about one-half of total shell length.  Spire calloused, callus terminating in front of the aperture; suture covered by callus.  Spire whorls vary from weakly to strongly spirally ribbed, 3-9 ribs per whorl, ribs ending at aperture.  Body whorl with calloused subsutural band, edged by a weak groove.  Non-calloused part of body whorl with microscopic axial and spiral striae.  Columellar pillar with 5-6 plaits; fasciolar band with central ridge, upper and lower halves flat and smooth; ancillid band well defined, bordered above by the ancillid groove and below by the strong, raised edge of the fasciolar band.  Non-calloused areas fawn; spire and subsutural band white; fasciolar band and pillar area white.  Operculum brown, corneous.

Size:Up to 28 mm in length.

Distribution: Endemic to Australia ; Clarence River , NSW, to Great Australian Bight , South Australia .

Habitat: Known from 66-457 metres.  Common.

Comparison: This is a deep water species, never taken as a beach shell.  It has no spiral brown bands, and has a weakly to strongly spirally ridged spire.

Synonyms: This species has been known as Amalda fusiformis (Petterd, 1886), but that name was  preoccupied and was replaced by Tate in 1893.  Iredale described a shell from off Merimbula, NSW, as  Alocospira fusiformis gaza Iredale, 1924, on the basis that it was "peculiarly elongate".   With the range of material now available it is apparent that the species varies in width, and Iredale’s specimen falls within the range of variation.  Examination of the types of Amalda lanceolata Ninomiya, 1991 shows this to be another synonym (new synonym). 

Remarks: This is the most common of the deep water species in NSW.  It is quite variable in shape, from tall and slender to short and squat, but consistent in colour, always without brown bands.

Figs 1,2: Brisbane Water, Broken Bay, NSW (C.424277, both specimens)


Copyright Des Beechey 2004