Hirsutonuphis (Polychaeta : Onuphidae) from Australia, with a discussion of setal progression in juveniles

This study recognises five Australian species of Hirsutonuphis, of which three are newly described; a key to adults is provided. Juvenile stages of the three new species, ranging from recently settled to near adult individuals, are described, with emphasis on the appearance and replacement of provisional and permanent hooks. Anterior pseudocompound hooks are generally preceded by compound falcigers. Two types of anterior provisional subacicular hooks, representing relict structures, occur in juveniles. Posterior provisional hooks, representing precursor subacicular hooks, occur in juveniles and the most posterior segments of adults. This study demonstrates that while setal progression in the genus shows species specific differences, it follows a pattern that is similar for allied genera but not identical for the whole family.