Tube ultrastructure of the fossil genus Rotularia Defrance, 1827 (Polychaeta, Serpulidae)

A mong Polychaete annelids, calcareous tubes occur in Serpulidae, Spirorbidae, Sabellidae, and Cirratulidae (Perkins, 1991; Fischer et al., 2000). The tubes of most serpulids are completely or partially cemented to the substrate. The fossil genus Rotularia has a peculiar unattached, spirally coiled tube, thus well distinguishable from the other known serpulids. Tube records of Rotularia are known from Mesozoic (Late Jurassic) (Ball, 1960; Stevens, 1967) to Early Tertiary sediments, becoming very common during the Cretaceous and Eocene (see Savazzi, 1995). It also has a global distribution (Wrigley, 1951; Ball, 1960; Keen, 1961; Regenhardt, 1961; Howell, 1962; Stevens, 1967; Chiplonkar and Tapaswi, 1973; Ware, 1975; Lommerzheim, 1979; Macellari, 1984; Jäger, 1993).