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Vanikoro cancellata (Lamarck, 1822) Description: Shell light in weight, spire slightly elevated. Protoconch smooth, elevated. Teleoconch initially with curved axial ribs crossed by about 10 spiral cords; 3-4 threads developing between cords on second whorl. Axial ribs broaden to low, axial folds on last whorl, often irregularly spaced; primary cords and threads persist producing cancellate surface. Aperture wide; outer lip semicircular, smooth; inner lip of aperture smooth. Umbilicus almost closed. Colour white. Periostracum thin, brown, with fine axial lamellae on the axial ribs. Size: Up to 25 mm high. Distribution: Indo-West Pacific. In Australia, south-western WA around the northern coast to Port Stephens, NSW. Habitat: Intertidal, and probably shallow subtidal, under rocks. Common in the tropics, uncommon in NSW. Comparison: V. cancellata has crisp sculpture on its spire, with a spiderweb-like pattern, and the umbilicus is almost closed. V. expansa has the early whorls with strong lamellae followed by fenestrate sculpture; the umbilicus is also almost closed. The fenestrate sculpture is visible even in very worn shells. V. sigaretiformis has the umbilicus more open than these two species. It has sculpture on its spire similar to the lamellae found on the spire of V. expansa, but does not go on to develop the strong fenestrate pattern. Synonymy: The name Vanikoro cancellata (Lamarck, 1822) is used with some hesitancy for this species, but is retained in the absence of good alternative information. This is probably the same as the species described as Vanikoro helicoidea (Le Guillou, 1842) by Cernohorsky (1978). Remarks: This species has a delicately sculptured spire, somewhat resembling a spider's web. The sculpture changes slowly from the crisp sculpture on the spire to being finely cancellate on the last whorl. Living shells are covered with a brown periostracum, usually absent in shells washed up on the beach. The anatomy of this species is described by Simone (2002). Fig. 1: Port Stephens, NSW (C.358931) Fig. 2: Same specimen as Fig. 1 Fig. 3: Detail of spire. Same specimen as Figs. 1 & 2. |
