Meeting Abstract
Capitellid polychaetes (Annelida) are common members of the marine benthos that superficially resemble earthworms. Morphological synapomorphies that define them include a thoracic region with mostly capillary chaetae and an abdominal region with hooded hooks. Generic and specific designations are often made with this chaetal formula, hooded hook morphology, and the presence or absence of other structures, e.g. genital hooks, anal cirri, and branchiae. Having so few characters has likely led to erroneous designations. Further confounding the topic is the Capitella cryptic species complex. Capitella capitata is commonly used as a biological indicator species due to its ubiquitous distribution and ability to tolerate high concentrations of pollutants. However, it was discovered in the 1970s that what is traditionally considered C. capitata is actually a group of several sibling species on the Massachusetts coast alone, with the number continually growing worldwide. Our research aims to delineate boundaries within this species complex using genetics and morphology. We sequenced mitochondrial markers for individuals of C. capitata and C. aciculata collected from Texas and Florida and analyzed them in conjunction with data available in GenBank. Our results indicate the presence of a Gulf of Mexico (GoM) clade that is distinct from populations in Canada and India. They also show that clades are defined more by location rather than by morphology, that is that there is more divergence intraspecifically GoM-wide than there is interspecifically in one location.
