Postlarval development of Nicolea uspiana (Polychaeta: Terebellidae)

ABSTRACT

The postlarval development of Nicolea uspiana (Nogueira, 2003), a small intertidal terebellid polychaete from rocky habitats on the southeastern and southern Brazilian coast, was studied based on postlarval, juvenile and adult specimens. The specimens, ranging from 8 to 43 segments, were collected between May 2006 and May 2007. The youngest postlarval specimen was found crawling outside of the tube. In specimens at different stages of growth, the number of ocelli and tentacles increased; the first pair of nephridial papillae appeared early (before 8-segmented specimen), and the second and third pairs appeared later (31-segmented specimen); the circulatory system only developed when the first pair of branchial bulbs arose (32-segmented specimen), and the second branchial pair appeared later (40-segmented specimen); and the inversion of the uncini positions in some rows occurred in the transition from larva to juvenile (17-segmented specimen). In the course of development, segments 2-3 lost the notochaetae, and segments 3-4 lost the neurochaetae. The changes involved in the development from postlarval to adult animals are illustrated by SEM micrographs and photographs.