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Monilea lentiginosa A. Adams 1853 Description: Shell variable in shape and sculpture; usually wider than high. Whorls rounded, sculptured with smooth to strongly beaded spiral ribs; on penultimate whorl, usually present as 4-5 pairs, sometimes with a secondary riblet between. Basal margin rounded. Base with 8-12 ribs, innermost within the umbilicus, with axial threads in the interspaces. Umbilicus open. Columella curved with a strong spiral rib in the umbilicus corresponding to reflected centre of columella. Outer lip thin, interior of aperture lirate. Colour cream, with axial streaks or splashes of brown; umbilicus white. Interior nacreous. Size: Up to 24 mm high, 24 mm wide. Distribution: Central Indo-West Pacific. In Australia, from Cockburn Sound, WA, to Sydney, NSW. Extinct around Sydney, present only as empty shells. Habitat: In muddy or sandy situations, at low tide and subtidally. Common. Comparison: Monilea callifera (Lamarck, 1822) (Synonym Monilea belcheri Philippi, 1849) is a similar species found offshore on the Great Barrier Reef and northwards to at least Papua New Guinea. It differs for M. lentiginosa by having finer sculpture on the base, and by having the umbilicus encircled by a spiral rib that has no spiral sculpture. In M. lentiginosa the spiral sculpture on the base extends into the umbilicus. Synonym: Talopena morti Iredale, 1929 is a synonym based on an unusually tall specimen, probably subfossil, dredged from Sydney Harbour. Several lots of specimens in the Australian Museum, dredged from Sydney Harbour by the dredge Triton, show a range in form from low to high as great as that found throughout the range of M. lentiginosa, so separation of the tall form as a distinct species is inappropriate. Remarks: Hickman & McLean (1990, p. 128, fig. 83) give figures of the external anatomy of Monilea callifera. Figs. 1,2: Port Stephens, NSW (C.017916) |
