Meeting Abstract
Chaetopterus is one of the most bizarre and readily recognized clades of marine Annelida. Members of the genus have evolved a remarkably tagmatized body plan, specialized for mucus-net suspension feeding. While Chaetopterus species have been used extensively as model organisms in studies of development, biomechanics, and biomedicine, the systematics of the genus remain problematic. Within the genus, morphological specialization to mucus-net suspension feeding contributes to low interspecific variation, while morphological plasticity and enormous regenerative capacity heighten intraspecific variability. As a result, all 23 species described before 2001 were synonymized at one time or another with the Mediterranean species Chaetopterus variopedatus, long considered a morphologically variable, cosmopolitan species. While some names have recently been resurrected from synonymy, the identities of Chaetopterus variopedatus, the type species C. pergamentaceus, and model organisms in the genus have remained unclear. New collections of C. variopedatus and C. pergamentaceus from their type localities, recent collections of specimens from the Indo-Pacific, and examination of type specimens have allowed morphological and genetic assessment of most species names within the genus. Three genes: cytochrome oxidase subunit I, 28S ribosomal RNA, and 18S ribosomal RNA, were sequenced for 47 specimens, with additional sequences included from GenBank. Phylogenetic relationships were assessed using Bayesian and maximum-likelihood methods. Morphological and genetic data show that many previously synonymized species names should be resurrected, and the current taxonomy underestimates the species diversity. Genetic data shows that while some species are wide-ranging, the distributions of most species are much more restricted than previously thought.
