Epitonium parspeciosum (Iredale, 1929)
Description: Shell broad for genus; whorls disconnected, joined only by axial ribs. Whorls rounded, with about 9 axial ribs. Ribs tall, rolled back, peaked, aligned from whorl to whorl. Whorls smooth or with faint spiral grooves in interspaces. Aperture oval, outer lip with normal rib externally. Umbilicus widely open. Colour uniformly tan with white ribs. Operculum unknown.
Size: Up to 21 mm in length.
Distribution: Known only from Sydney Harbour and Port Hacking, NSW.
Habitat: Dredged from Sydney Harbour by dredge Triton; beach shells from Port Hacking.
Comparison: This species is similar to the tropical species Epitonium pallasi (Kiener, 1838) but differs by the axial ribs being thinner, higher and consistently peaked, and by the whorls being more separated. The inter-whorl gap is about twice the average rib height in this species, but about equal to the average rib height in E. pallasi.
Synonymy: As with many other specimens obtained from Triton dredgings in Sydney Harbour, this species may be based on a fossil shell of a tropical species, possibly Epitonium pallasi neglectum (A. Adams & Reeve, 1850).
Remarks: Wilson (1993, p. 278) gives the range of this species as "Port Stephens to Sydney Harbour, NSW", but this is not supported by the Australian Museum collection. He also reported E. pallasi as far south as Port Stephens, NSW, but its occurrence south of Hervey Bay, Queensland, is based on only one specimen, probably mislocalised, in the Australian Museum.
Fig. 1: HOLOTYPE Sydney Harbour, by dredge Triton (C.060640)
Fig. 2: Sydney Harbour, by dredge Triton (C.346229)
Copyright Des Beechey 2008