Research Training Program

Abigail J. Knee
University of Rhode Island
Kingston, Rhode Island

Kristian Fauchald, Ph.D.
Supervising Scientist
Dept. of Systematic Biology
Division of Worms

"The Research Training Program not only supported my personal project in systematic biology, but it also allowed me to explore so many other intriguing areas of natural history."

A cladistic analysis of the polychaete genus Halosydna

Historically, the study of bristleworms (class Polychaeta) has been wrought with misclassifications and sloppy organization. Within the bristleworms, one family of marine scale worms has particularly mystified taxonomists. This family, Polynoidae, consists of a group of these flattened scale worms without any unifying features of its own. The practice of removing other closely-related families from the former, all-encompassing grouping of scale worms left an assorted assemblage behind; those in the Polynoidae are linked to each other only by the fact that they have scales and do not fit with the extracted taxa. Due to the inconsistencies of its previous taxonomic classification, this leftover family requires a major revision to better understand its species' relationships. Using cladistics, a branch of systematic biology based on the premise that species represent descent with modification from a common ancestor, this research sought to determine the evolutionary relationships within the polynoid genus Halosydna Kinberg 1855 and in relation to its sister taxa. Eight species attributed to Halosydna and ten species of other closely related scale worms were observed under both compound and dissecting microscopes. Eighty-eight characteristics were described, including the features of their head, the decorations on their paired scales and back, and the type of notches on the bristles along their sides. A computer software program known as PAUP (Phylogenetic Analysis Using Parsimony) revealed the simplest paths of speciation based on shared, derived characters. Overall, the results show the Halosydna species to organize more closely with each other than to other taxa, supporting the genus' validity. Two undescribed species, H. augeneri, a milky-white worm from Peru with tiny bumps on its scales, and H. riojai, a pinky-yellow worm from the Gulf of California with large bumps on its scales, also were discovered in the museum collection. Descriptions of these two species are to be submitted for publication next year.

This research was supported by a grant from the National Science Foundation Research Experiences for Undergraduates program, Award Number DBI-9820303.

Letter of Gratitude