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Alaba monile A. Adams, 1862 Description: Shell conical, height to width ratio variable. Shell transparent or opaque when fresh, becoming opaque with age. Whorls rounded to angled, smooth or with a spiral row of strong nodules at lower quarter. Aperture without siphonal canal; outer lip thin, slightly flared anteriorly; columella smooth, straight, umbilicus absent. Colour pattern variable; dark brown interrupted band at periphery, weakening to spiral lines in some specimens, or absent altogether; wavy brown axial lines variable in extent and strength. Operculum corneous. Size: Up to 7 mm in length. Distribution: Endemic to Australia; central NSW, around southern Australia to south-western WA. Habitat: Lives on algae and seagrass in sheltered and exposed situations, intertidally and subtidally; common to abundant. Common in beach shell grit. Comparison: See A. opiniosa. Synonymy: The synonymy is unclear; see the family introduction. Remarks: This has always been and remains a problematic species, as shown by the vague description and the variation in the figured specimens. Fig. 1 and 2 show specimens from two lots from Middle Harbour, NSW. There is variability in degree of nodulation, whorl shape, height to width ratio, and colour pattern, but there appears to be a continuum within each of these characters. Similar variation occurs between specimens from single localities in Victoria, South Australia and Western Australia. If it is only one species it is remarkably variable; if there is more than one species involved, shells offer no clues to where the species boundaries should be drawn. Fig. 1: Chinamans Beach, Middle Harbour, NSW (C.329891) Fig. 2: Middle Harbour, NSW (C.032622) |
