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PLESIOTROCHIDAE |
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Plesiotrochus monachus (Crosse & Fischer, 1864) Description: Spire tall, nearly straight sided, up to 9 whorls. Whorls strongly angled at lower third, with axial folds that form nodules on periphery; strong cord immediately above suture, continuing onto last whorl. Some shells with thickened, raised varices, variable in number. Entire surface sculptured with spiral threads, about 10 per whorl, absent or weak on peripheral angulation and on nodules. Aperture with siphonal canal; columella and interior of outer lip smooth. Outer lip rarely with thickened, raised varix. Colour fawn, with tan splashes on nodules and lower spiral cord, sometimes extending into irregular axial streaks; covered with mid-brown periostracum when not worn. Size: Up to 17 mm in length. Distribution: Endemic to Australia: Twofold Bay, NSW, southwards and around southern Australia to Geraldton, WA, including Tasmania. Habitat: The habitat in South Australia was reported as "Found in large numbers on algae on silty bottom, or occasionally on Posidonia seagrass from 5 m to 20 m depth" (Ludbrook & Gowlett-Holmes, 1989). Rare in NSW. Remarks: Any whorl after about the fourth may carry varices, varying from zero to three per whorl, but there is rarely a varix on the outer lip. Fig. 1: D'Entrecasteaux Channel, Tasmania (C.396765)
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