Newtoniellidae – Ataxocerithiinae: Ataxocerithium serotinum (A. Adams, 1855) (‘square-mouthed false-creeper’)

Synonym(s): serotinum A. Adams, 1855 rhodostomum A. Adams, 1855 tubulus Dunker, 1871 conturbatum Iredale, 1936.

Typical shell-length 20 mm. Lives subtidally and offshore amongst sponges. Native. Endemic to southeastern and southwestern Australia (NSW, TAS, VIC, SA and WA). In Tasmanian waters, this is a widespread species but not commonly beached; most likely to be found in the N, where specimens tend to be larger.